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Zhang D, Zhu Z, Xiao X, Fang YH, Xiao T, Wang X, Jiang SD, Zhao D. An Air-Stable Carbon-Centered Triradical with a Well-Addressable Quartet Ground State. J Am Chem Soc 2024; 146:21752-21761. [PMID: 39056815 DOI: 10.1021/jacs.4c05898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/28/2024]
Abstract
Organic polyradicals with a high-spin ground state and quantum magnetic properties suitable for spin manipulation are valuable materials for diverse innovative technologies, including quantum devices. However, the typically high reactivity and low stability of conventional polyradicals present a major obstacle to such applications. In this study, a highly stable carbon-centered triradical TR with a quartet ground state and excellent stability (τ1/2 of ∼90 days in air-saturated toluene at room temperature) is achieved, which shows apposite magnetic anisotropy and Zeeman splitting partition with favorable addressability. By virtue of the optimal stability, thorough structural and magnetic characterizations are realized. With X-ray crystallography unambiguously proving the molecular structure, the quartet ground state (ΔED-Q = 0.78 kcal/mol) is confirmed by the SQUID measurements, while the cw- and pulsed EPR techniques offer additional supportive evidence for the high-spin nature. Remarkably, owing to the easily attained magnetic anisotropy, selective excitations between different Zeeman splitting levels are successfully demonstrated with TR in its frozen toluene solution without the requirement for special alignment, which is unprecedented for organic polyradicals. Along with the millisecond spin-lattice relaxation and microsecond coherence time manifested by TR, this triradical is promising for potential coherent spin manipulation applications as a multienergy-level quantum information carrier.
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Affiliation(s)
- Di Zhang
- Beijing National Laboratory for Molecular Sciences, Centre for the Soft Matter Science and Engineering, the Key Laboratory of Polymer Chemistry and Physics of the Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
| | - Ziqi Zhu
- Beijing National Laboratory for Molecular Sciences, Centre for the Soft Matter Science and Engineering, the Key Laboratory of Polymer Chemistry and Physics of the Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
| | - Xiao Xiao
- Beijing National Laboratory for Molecular Sciences, Centre for the Soft Matter Science and Engineering, the Key Laboratory of Polymer Chemistry and Physics of the Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
| | - Yu-Hui Fang
- Beijing National Laboratory for Molecular Sciences, Centre for the Soft Matter Science and Engineering, the Key Laboratory of Polymer Chemistry and Physics of the Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
| | - Tongtong Xiao
- Beijing National Laboratory for Molecular Sciences, Centre for the Soft Matter Science and Engineering, the Key Laboratory of Polymer Chemistry and Physics of the Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
| | - Xiaoge Wang
- Beijing National Laboratory for Molecular Sciences, Centre for the Soft Matter Science and Engineering, the Key Laboratory of Polymer Chemistry and Physics of the Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
| | - Shang-Da Jiang
- Spin-X Institute, School of Chemistry and Chemical Engineering, State Key Laboratory of Luminescent Materials and Devices, Guangdong-Hong Kong-Macao Joint Laboratory of Optoelectronic and Magnetic Functional Materials, South China University of Technology, Guangzhou 510641, China
| | - Dahui Zhao
- Beijing National Laboratory for Molecular Sciences, Centre for the Soft Matter Science and Engineering, the Key Laboratory of Polymer Chemistry and Physics of the Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
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2
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Zayakin IA, Petunin PV, Postnikov PS, Dmitriev AA, Gritsan NP, Dorovatovskii P, Korlyukov A, Fedin MV, Bogomyakov AS, Akyeva AY, Novikov RA, Shangin PG, Syroeshkin MA, Burykina JV, Tretyakov EV. Toward New Horizons in Verdazyl-Nitroxide High-Spin Systems: Thermally Robust Tetraradical with Quintet Ground State. J Am Chem Soc 2024; 146:13666-13675. [PMID: 38709144 DOI: 10.1021/jacs.4c04391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/07/2024]
Abstract
High-spin organic tetraradicals with significant intramolecular exchange interactions have high potential for advanced technological applications and fundamental research, but examples reported to date exhibit limited stability and processability. In this work, we designed the first tetraradical based on an oxoverdazyl core and nitronyl nitroxide radicals and successfully synthesized it using a palladium-catalyzed cross-coupling reaction of an oxoverdazyl radical bearing three iodo-phenylene moieties with a gold(I) nitronyl nitroxide-2-ide complex in the presence of a recently developed efficient catalytic system. The molecular and crystal structures of the tetraradical were confirmed by single crystal X-ray diffraction analysis. The tetraradical possesses good thermal stability with decomposition onset at ∼125 °C in an inert atmosphere; in a toluene solution upon prolonged heating at 90 °C in air, no decomposition was observed. The resulting unique verdazyl-nitroxide conjugate was thoroughly studied using a range of experimental and theoretical techniques, such as SQUID magnetometry of polycrystalline powders, EPR spectroscopy in various matrices, cyclic voltammetry, and high-level quantum chemical calculations. All collected data confirm the high thermal stability of the resulting tetraradical and quintet multiplicity of its ground state, which makes the synthesis of this important paramagnet a new milestone in the field of creating high-spin systems.
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Affiliation(s)
- Igor A Zayakin
- N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Ave. 47, Moscow 119991, Russian Federation
| | - Pavel V Petunin
- Tomsk Polytechnic University, Tomsk 634050, Russian Federation
| | | | - Alexey A Dmitriev
- V.V. Voevodsky Institute of Chemical Kinetics and Combustion, Siberian Branch of Russian Academy of Sciences, Institutskaya Str. 3, Novosibirsk 630090, Russian Federation
| | - Nina P Gritsan
- V.V. Voevodsky Institute of Chemical Kinetics and Combustion, Siberian Branch of Russian Academy of Sciences, Institutskaya Str. 3, Novosibirsk 630090, Russian Federation
| | | | - Alexander Korlyukov
- A.N. Nesmeyanov Institute of Organoelement Compounds, 28 Vavilov Str., Moscow 119991, Russian Federation
| | - Matvey V Fedin
- International Tomography Center, Siberian Branch of Russian Academy of Sciences, Institutskaya Str. 3a, Novosibirsk 630090, Russian Federation
| | - Artem S Bogomyakov
- International Tomography Center, Siberian Branch of Russian Academy of Sciences, Institutskaya Str. 3a, Novosibirsk 630090, Russian Federation
| | - Anna Ya Akyeva
- N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Ave. 47, Moscow 119991, Russian Federation
| | - Roman A Novikov
- N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Ave. 47, Moscow 119991, Russian Federation
| | - Pavel G Shangin
- N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Ave. 47, Moscow 119991, Russian Federation
| | - Mikhail A Syroeshkin
- N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Ave. 47, Moscow 119991, Russian Federation
| | - Julia V Burykina
- N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Ave. 47, Moscow 119991, Russian Federation
| | - Evgeny V Tretyakov
- N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Ave. 47, Moscow 119991, Russian Federation
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3
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Duan JJ, Yang XQ, Li R, Li X, Chen T, Wang D. N-Heterocyclic Carbene-Derived 1,3,5-Trimethylenebenzene: On-Surface Synthesis and Electronic Structure. J Am Chem Soc 2024; 146:13025-13033. [PMID: 38693826 DOI: 10.1021/jacs.3c14298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2024]
Abstract
1,3,5-Trimethylenebenzene (1,3,5-TMB), a 3-fold-symmetric triradical with a high-spin ground state, is an attractive platform for investigating the unique spin properties of π-conjugated triangular triradicals. Here, we report the on-surface synthesis of N-heterocyclic carbene (NHC)-derived 1,3,5-TMB (N-TMB) via surface-assisted C-C and C-N coupling reactions on Au(111). The chemical and electronic structures of N-TMB on the Au(111) surface are revealed with atomic precision using scanning tunneling microscopy and noncontact atomic force microscopy, combined with density functional theory (DFT) calculations. It is demonstrated that there is substantial charge transfer between N-TMB and the substrate, resulting in a positively charged N-TMB on Au(111). DFT calculations at the UB3LYP/def2-TZVP level of theory and multireference method, e.g., CASSCF/NEVPT2, indicate that N-TMB possesses a doublet ground state with reduced Cs symmetry in the gas phase, contrasting the quartet ground state of 1,3,5-TMB with D3h symmetry, and exhibits a doublet-quartet energy gap of -0.80 eV. The incorporation of NHC structures and the extended π-conjugation promote the spin-orbital overlaps in N-TMB, leading to Jahn-Teller distortion and the formation of a robust doublet state. Our results not only demonstrate the fabrication of polyradicals based on NHC but also shed light on the effect of NHC and π-conjugation on the electronic structure and spin coupling, which opens up new possibilities for precisely regulating the spin-spin exchange coupling of organic polyradicals.
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Affiliation(s)
- Jun-Jie Duan
- CAS Key Laboratory of Molecular Nanostructure and Nanotechnology, CAS Research/Education Center for Excellence in Molecular Sciences, Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xue-Qing Yang
- CAS Key Laboratory of Molecular Nanostructure and Nanotechnology, CAS Research/Education Center for Excellence in Molecular Sciences, Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Ruoning Li
- CAS Key Laboratory of Molecular Nanostructure and Nanotechnology, CAS Research/Education Center for Excellence in Molecular Sciences, Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Xin Li
- Center for Carbon-based Electronics and Key Laboratory for the Physics and Chemistry of Nanodevices, School of Electronics, Peking University, Beijing 100871, China
| | - Ting Chen
- CAS Key Laboratory of Molecular Nanostructure and Nanotechnology, CAS Research/Education Center for Excellence in Molecular Sciences, Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Dong Wang
- CAS Key Laboratory of Molecular Nanostructure and Nanotechnology, CAS Research/Education Center for Excellence in Molecular Sciences, Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
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4
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Steffenfauseweh H, Vishnevskiy YV, Neumann B, Stammler HG, de Bruin B, Ghadwal RS. N-Heterocyclic Carbene Analogues of Wittig Hydrocarbon. Chemistry 2024; 30:e202400879. [PMID: 38437163 DOI: 10.1002/chem.202400879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2024] [Accepted: 03/04/2024] [Indexed: 03/06/2024]
Abstract
N-Heterocyclic carbene (NHC) analogues of Wittig hydrocarbon, [(NHC)(Stil)(NHC)] (3a-c) (NHC = SIPr (1a) = C[N(Dipp)CH2]2, Dipp = 2,6-iPr2C6H3; IPr (1b) = C[N(Dipp)CH]2; Me-IPr (1c) = C[N(Dipp)CMe]2 and Stil = C6H4CHCHC6H4) have been reported as crystalline solids. 3a-c are prepared by two-electron reductions of the corresponding bis-1,3-imidazoli(ni)um bromides [(NHC)(Stil)NHC)](Br)2 (2a-c) with KC8 in >94 % yields. 2a-c are accessible by the nickel catalyzed direct C-C coupling of NHCs (1a-c) with (E)-4,4'-dibromostilbene. One-electron oxidation of 3a,b yields the corresponding radical cations [(NHC)(Stil)NHC)]B(C6F5)4 4a,b. All compounds have been characterized by UV-Vis/NMR/EPR spectroscopy as well as 2a, 3a, and 3b by single crystal X-ray diffraction. The electronic structures of representative systems have been analyzed by quantum chemical calculations.
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Affiliation(s)
- Henric Steffenfauseweh
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstrasse 25, D-33615, Bielefeld, Germany
| | - Yury V Vishnevskiy
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstrasse 25, D-33615, Bielefeld, Germany
| | - Beate Neumann
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstrasse 25, D-33615, Bielefeld, Germany
| | - Hans-Georg Stammler
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstrasse 25, D-33615, Bielefeld, Germany
| | - Bas de Bruin
- University of Amsterdam (UvA), Faculty of Science, Van 't Hoff Institute for Molecular Sciences (HIMS), Homogeneous and Supramolecular Catalysis Group, Science Park 904, 1098 XH, Amsterdam, The Netherlands
| | - Rajendra S Ghadwal
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstrasse 25, D-33615, Bielefeld, Germany
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5
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Bodzioch A, Obijalska E, Jakubowski R, Celeda M, Gardias A, Trzybiński D, Tokarz P, Szczytko J, Woźniak K, Kaszyński P. Electronic and Magnetic Interactions in 6-Oxoverdazyl Diradicals: Connection through N(1) vs C(3) Revisited. J Org Chem 2024; 89:6306-6321. [PMID: 38626755 PMCID: PMC11077500 DOI: 10.1021/acs.joc.4c00303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Revised: 03/11/2024] [Accepted: 03/29/2024] [Indexed: 04/18/2024]
Abstract
Four isomeric di-6-oxoverdazyl diradicals connected at their N(1) or C(3) positions with either 1,3- or 1,4-phenylene linkers were obtained and characterized by spectroscopic, electrochemical, magnetic, and structural methods. These results were compared to those for the corresponding 6-oxoverdazyl monoradicals. UV-vis spectroscopy demonstrated that only the N(1)-connected para-through-benzene diradical has a distinct spectrum with significant bathochromic and hypsochromic shifts relative to the remaining species. Electrochemical analysis revealed two one-electron reduction processes in all diradiacals, while only the N(1)-connected para-through-benzene diradical exhibits two one-electron oxidation processes separated by 0.10 V. Variable temperature EPR measurements in polystyrene solid solutions gave negative mean exchange interaction energies J for all diradicals, suggesting the dominance of conformers with significant intramolecular antiferromagnetic interactions for the meta-through-benzene isomers. DFT calculations predict a small preference for the triplet state with the ΔES-T of about 0.25 kcal mol-1 for both meta-through-benzene connected diradicals.
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Affiliation(s)
- Agnieszka Bodzioch
- Centre
of Molecular and Macromolecular Studies, Polish Academy of Sciences, 90-363 Łódź, Poland
| | | | - Rafał Jakubowski
- Centre
of Molecular and Macromolecular Studies, Polish Academy of Sciences, 90-363 Łódź, Poland
| | | | - Anita Gardias
- Institute
of Experimental Physics Faculty of Physics, University of Warsaw, 02-093 Warsaw, Poland
| | - Damian Trzybiński
- Biological
and Chemical Research Centre, University
of Warsaw, 02-089 Warsaw, Poland
| | - Paweł Tokarz
- Faculty of
Chemistry, University of Łódź, 91-403 Łódź, Poland
| | - Jacek Szczytko
- Institute
of Experimental Physics Faculty of Physics, University of Warsaw, 02-093 Warsaw, Poland
| | - Krzysztof Woźniak
- Biological
and Chemical Research Centre, University
of Warsaw, 02-089 Warsaw, Poland
| | - Piotr Kaszyński
- Centre
of Molecular and Macromolecular Studies, Polish Academy of Sciences, 90-363 Łódź, Poland
- Faculty of
Chemistry, University of Łódź, 91-403 Łódź, Poland
- Department
of Chemistry, Middle Tennessee State University, Murfreesboro, Tennessee 37132, United States
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6
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Guo H, Lovell JB, Shu C, Pink M, Morton M, Rajca S, Rajca A. Chiral π-Conjugated Double Helical Aminyl Diradical with the Triplet Ground State. J Am Chem Soc 2024; 146:9422-9433. [PMID: 38501228 DOI: 10.1021/jacs.4c02057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/20/2024]
Abstract
We report a neutral high-spin diradical of chiral C2-symmetric bis[5]diazahelicene with ΔEST ≈ 0.4 kcal mol-1, as determined by EPR spectroscopy/SQUID magnetometry. The diradical is the most persistent among all high-spin aminyl radicals reported to date by a factor of 20, with a half-life of up to 6 days in 2-MeTHF at room temperature. Its triplet ground state and excellent persistence may be associated with the unique spin density distribution within the dihydrophenazine moiety, which characterizes two effective 3-electron C-N bonds analogous to the N-O bond of a nitroxide radical. The enantiomerically enriched (ee ≥ 94%) (MM)- and (PP)-enantiomers of the precursors to the diradicals are obtained by either preparative chiral supercritical fluid chromatography or resolution via functionalization with the chiral auxiliary of the C2-symmetric racemic tetraamine. The barrier for the racemization of the solid tetraamine is ΔG‡ = 43 ± 0.01 kcal mol-1 in the 483-523 K range. The experimentally estimated lower limit of the barrier for the racemization of a diradical, ΔG‡ ≥ 26 kcal mol-1 in 2-MeTHF at 293 K, is comparable to the DFT-determined barrier of ΔG‡ = 31 kcal mol-1 in the gas phase at 298 K. While the enantiomerically pure tetraamine displays strong chiroptical properties, with anisotropy factor |g| = |Δε|/ε = 0.036 at 376 nm, |g| ≈ 0.005 at 548 nm of the high-spin diradical is comparable to that recently reported triplet ground-state diradical dication. Notably, the radical anion intermediate in the generation of diradical exhibits a large SOMO-HOMO inversion, SHI = 35 kcal mol-1.
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Affiliation(s)
- Haoxin Guo
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, United States
| | - Joshua B Lovell
- Teledyne ISCO, 4700 Superior Street, Lincoln, Nebraska 68504-1328, United States
| | - Chan Shu
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, United States
| | - Maren Pink
- IUMSC, Department of Chemistry, Indiana University, Bloomington, Indiana 47405-7102, United States
| | - Martha Morton
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, United States
| | - Suchada Rajca
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, United States
| | - Andrzej Rajca
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, United States
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7
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Saha C, Huda MM, Sabuj MA, Rai N. Elucidating the structure of donor-acceptor conjugated polymer aggregates in liquid solution. SOFT MATTER 2024; 20:1824-1833. [PMID: 38305724 DOI: 10.1039/d3sm01458d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2024]
Abstract
High-spin donor-acceptor conjugated polymers are extensively studied for their potential applications in magnetic and spintronic devices. Inter-chain charge transfer among these high-spin polymers mainly depends on the nature of the local structure of the thin film and π-stacking between the polymer chains. However, the microscopic structural details of high-spin polymeric materials are rarely studied with an atomistic force field, and the molecular-level local structure in the liquid phase remains ambiguous. Here, we have examined the effects of oligomer chain length, side chain, and processing temperature on the organization of the high-spin cyclopentadithiophene-benzobisthiadiazole donor-acceptor conjugated polymer in chloroform solvent. We find that the oligomers display ordered aggregates whose structure depends on their chain length, with an average π-stacking distance of 3.38 ± 0.03 Å (at T = 298 K) in good agreement with the experiment. Also, the oligomers with longer alkyl side chains show better solvation and a shorter π-stacking distance. Furthermore, the clusters grow faster at higher temperature with more ordered aggregation between the oligomer chains.
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Affiliation(s)
- Chinmoy Saha
- Dave C. Swalm School of Chemical Engineering, and Center for Advanced Vehicular System, Mississippi State University, Mississippi State, MS-39762, USA.
| | - Md Masrul Huda
- Dave C. Swalm School of Chemical Engineering, and Center for Advanced Vehicular System, Mississippi State University, Mississippi State, MS-39762, USA.
| | - Md Abdus Sabuj
- Dave C. Swalm School of Chemical Engineering, and Center for Advanced Vehicular System, Mississippi State University, Mississippi State, MS-39762, USA.
| | - Neeraj Rai
- Dave C. Swalm School of Chemical Engineering, and Center for Advanced Vehicular System, Mississippi State University, Mississippi State, MS-39762, USA.
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8
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Tretyakov EV, Zayakin IA, Dmitriev AA, Fedin MV, Romanenko GV, Bogomyakov AS, Akyeva AY, Syroeshkin MA, Yoshioka N, Gritsan NP. A Nitronyl Nitroxide-Substituted Benzotriazinyl Tetraradical. Chemistry 2024; 30:e202303456. [PMID: 37988241 DOI: 10.1002/chem.202303456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Revised: 11/20/2023] [Accepted: 11/21/2023] [Indexed: 11/23/2023]
Abstract
High-spin organic tetraradicals with significant intramolecular exchange interactions have high potential for advanced technological applications and fundamental research, but those synthesized to date possess limited stability and processability. In this work, we have designed a tetraradical based on the Blatter's radical and nitronyl nitroxide radical moieties and successfully synthesized it by using the palladium-catalyzed cross-coupling reaction of a triiodo-derivative of the 1,2,4-benzotriazinyl radical with gold(I) nitronyl nitroxide-2-ide complex in the presence of a newly developed efficient catalytic system. The molecular and crystal structure of the tetraradical was confirmed by X-ray diffraction analysis. The tetraradical possesses good thermal stability with decomposition onset at ∼150 °C under an inert atmosphere and exhibits reversible redox waves at -0.54 and 0.45 V versus Ag/AgCl. The magnetic properties of the tetraradical were characterized by SQUID magnetometry of polycrystalline powders and EPR spectroscopy in various matrices. The collected data, analyzed by using high-level quantum chemical calculations, confirmed that the tetraradical has a triplet ground state and a nearby excited quintet state. The unique high stability of the prepared triazinyl-nitronylnitroxide tetraradical is a new milestone in the field of creating high-spin systems.
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Affiliation(s)
- Evgeny V Tretyakov
- N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Ave. 47, 119991, Moscow, Russian Federation
| | - Igor A Zayakin
- N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Ave. 47, 119991, Moscow, Russian Federation
| | - Alexey A Dmitriev
- V.V. Voevodsky Institute of Chemical Kinetics and Combustion, Siberian Branch of Russian Academy of Sciences, Institutskaya Str. 3, 630090, Novosibirsk, Russian Federation
| | - Matvey V Fedin
- International Tomography Center, Siberian Branch of Russian Academy of Sciences, Institutskaya Str. 3a, 630090, Novosibirsk, Russian Federation
| | - Galina V Romanenko
- International Tomography Center, Siberian Branch of Russian Academy of Sciences, Institutskaya Str. 3a, 630090, Novosibirsk, Russian Federation
| | - Artem S Bogomyakov
- International Tomography Center, Siberian Branch of Russian Academy of Sciences, Institutskaya Str. 3a, 630090, Novosibirsk, Russian Federation
| | - Anna Ya Akyeva
- N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Ave. 47, 119991, Moscow, Russian Federation
| | - Mikhail A Syroeshkin
- N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Ave. 47, 119991, Moscow, Russian Federation
| | - Naoki Yoshioka
- Department of Applied Chemistry Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, 223-8522 Kanagawa, Japan
| | - Nina P Gritsan
- V.V. Voevodsky Institute of Chemical Kinetics and Combustion, Siberian Branch of Russian Academy of Sciences, Institutskaya Str. 3, 630090, Novosibirsk, Russian Federation
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9
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Wu Y, Cao H, Bakirov MM, Sukhanov AA, Li J, Liao S, Xiao X, Zhao J, Li MD, Kandrashkin YE. A Rational Way to Control the Triplet State Wave Function Confinement of Organic Chromophores: Effect of the Connection Sites and Spin Density Distribution-Guided Molecular Structure Design Principles in Bodipy Dimers. J Phys Chem Lett 2024; 15:959-968. [PMID: 38252167 DOI: 10.1021/acs.jpclett.3c03225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2024]
Abstract
To study the intersystem crossing (ISC) and the spatial confinement of the triplet excited states of organic chromophores, we prepared a series of Bodipy dimers. We found that the connection position of the two units has a significant effect on the absorption and fluorescence. Singlet oxygen quantum yields of 3.8-12.4% were observed for the dimers, which are independent of solvent polarity. Nanosecond transient absorption spectra indicate the population of long-lived triplet excited states with lifetimes (τT) of 45-454 μs. Pulsed laser-excited time-resolved electron paramagnetic resonance (TREPR) spectra show that the T1 triplet states are essentially delocalized, which is different from the case for the previously reported Bodipy dimers. The TREPR spectra of the triplet states imply that the delocalization over the whole dimer essentially depends on the electron density of the carbon atoms at the connection sites. This property may become a universal rule for controlling the T1 state confinement in multichromophore organic molecules.
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Affiliation(s)
- Yanran Wu
- State Key Laboratory of Fine Chemicals, Frontiers Science Center for Smart Materials, School of Chemical Engineering, Dalian University of Technology, Dalian 116024, P. R. China
| | - Huaiman Cao
- State Key Laboratory of Fine Chemicals, Frontiers Science Center for Smart Materials, School of Chemical Engineering, Dalian University of Technology, Dalian 116024, P. R. China
| | - Marcel M Bakirov
- Zavoisky Physical-Technical Institute, FRC Kazan Scientific Center of Russian Academy of Sciences, Kazan 420029, Russia
| | - Andrey A Sukhanov
- Zavoisky Physical-Technical Institute, FRC Kazan Scientific Center of Russian Academy of Sciences, Kazan 420029, Russia
| | - Jiayu Li
- Department of Chemistry and Key Laboratory for Preparation and Application of Ordered Structural Materials of Guangdong Province, Shantou University, Shantou 515063, P. R. China
| | - Sheng Liao
- Department of Chemistry and Key Laboratory for Preparation and Application of Ordered Structural Materials of Guangdong Province, Shantou University, Shantou 515063, P. R. China
| | - Xiao Xiao
- State Key Laboratory of Fine Chemicals, Frontiers Science Center for Smart Materials, School of Chemical Engineering, Dalian University of Technology, Dalian 116024, P. R. China
| | - Jianzhang Zhao
- State Key Laboratory of Fine Chemicals, Frontiers Science Center for Smart Materials, School of Chemical Engineering, Dalian University of Technology, Dalian 116024, P. R. China
- State Key Laboratory of Chemistry and Utilization of Carbon Based Energy Resources, College of Chemistry, Xinjiang University, Urumqi 830017, P. R. China
| | - Ming-De Li
- Department of Chemistry and Key Laboratory for Preparation and Application of Ordered Structural Materials of Guangdong Province, Shantou University, Shantou 515063, P. R. China
| | - Yuri E Kandrashkin
- Zavoisky Physical-Technical Institute, FRC Kazan Scientific Center of Russian Academy of Sciences, Kazan 420029, Russia
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10
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Haga N, Ishida T. A Triplet/Singlet Ground-State Switch via the Steric Inhibition of Conjugation in 4,6-Bis(trifluoromethyl)-1,3-phenylene Bisnitroxide. Molecules 2023; 29:70. [PMID: 38202653 PMCID: PMC10779647 DOI: 10.3390/molecules29010070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 12/12/2023] [Accepted: 12/19/2023] [Indexed: 01/12/2024] Open
Abstract
Ground triplet 4,6-bis(trifluoromethyl)-1,3-phenylene bis(tert-butyl nitroxide) (TF2PBN) reacted with [Y(hfac)3(H2O)2] (hfac = 1,1,1,5,5,5-hexafluoropentane-2,4-dionate), affording a doubly hydrogen-bonded adduct [Y(hfac)3(H2O)2(TF2PBN)]. The biradical was recovered from the adduct through recrystallization. Crystallographic analysis indicates that the torsion angles (|θ| ≤ 90°) between the benzene ring and nitroxide groups were 74.9 and 84.8° in the adduct, which are larger than those of the starting material TF2PBN. Steric congestion due to o-trifluoromethyl groups gives rise to the reduction of π-conjugation. Two hydrogen bonds enhance this deformation. Susceptometry of the adduct indicates a ground singlet with 2J/kB = -128(2) K, where 2J corresponds to the singlet-triplet gap. The observed magneto-structure relation is qualitatively consistent with Rajca's pioneering work. A density functional theory calculation at the UB3LYP/6-311+G(2d,p) level using the atomic coordinates determined provided a result of 2J/kB = -162.3 K for the adduct, whilst the corresponding calculation on intact TF2PBN provided +87.2 K. After a comparison among a few known compounds, the 2J vs. |θ| plot shows a negative slope with a critical torsion of 65(3)°. The ferro- and antiferromagnetic coupling contributions are balanced in TF2PBN, being responsible for ground-state interconversion by means of small structural perturbation like hydrogen bonds.
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Affiliation(s)
| | - Takayuki Ishida
- Department of Engineering Science, The University of Electro-Communications, Chofu 182-8585, Tokyo Prefecture, Japan
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11
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Zhu Z, Zhang D, Xiao T, Fang YH, Xiao X, Wang XG, Jiang SD, Zhao D. Rational Design of an Air-Stable, High-Spin Diradical with Diazapyrene. Angew Chem Int Ed Engl 2023; 62:e202314900. [PMID: 37851470 DOI: 10.1002/anie.202314900] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Revised: 10/18/2023] [Accepted: 10/18/2023] [Indexed: 10/19/2023]
Abstract
Stable carbon-based polyradicals exhibiting strong spin-spin coupling and slow depolarization processes are particularly attractive functional materials. A new molecular motif synthesized by a convenient method that allows the integration of stable, high-spin radicals to (hetero)aromatic polycycles has been developed, as illustrated by a non-Kekulé diradical showing a triplet ground state with long persistency (τ1/2 ≈31 h) in air. Compared to the widely used 1,3-phenylene, the newly designed (diaza)pyrene-4,10-diyl moiety is for the first time demonstrated to confer ferromagnetic (FM) spin coupling, allowing delocalized non-disjoint SOMOs. With the X-ray crystallography unambiguously proving the diradical structure, the triplet ground state was thoroughly characterized. A large ΔES-T of 1.1 kcal/mol, proving the strong FM coupling effect, was revealed consistently by superconducting quantum interference device (SQUID) measurements and variable-temperature electron paramagnetic resonance (EPR) spectroscopy, while the zero-field splitting and triplet nutation characters were examined by continuous-wave and pulsed EPR spectroscopy. A millisecond spin-lattice relaxation time was also detected. The current study not only offers a new molecular motif enabling FM coupling between carbon-based spins, but more importantly presents a general method for installing stable polyradicals into functional π-systems.
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Affiliation(s)
- Ziqi Zhu
- Beijing National Laboratory for Molecular Sciences, Center for the Soft Matter Science and Engineering, the Key Laboratory of Polymer Chemistry and Physics of the Ministry of Education, College of Chemistry, Peking University, Beijing, China
| | - Di Zhang
- Beijing National Laboratory for Molecular Sciences, Center for the Soft Matter Science and Engineering, the Key Laboratory of Polymer Chemistry and Physics of the Ministry of Education, College of Chemistry, Peking University, Beijing, China
| | - Tongtong Xiao
- Beijing National Laboratory for Molecular Sciences, Center for the Soft Matter Science and Engineering, the Key Laboratory of Polymer Chemistry and Physics of the Ministry of Education, College of Chemistry, Peking University, Beijing, China
| | - Yu-Hui Fang
- Beijing National Laboratory for Molecular Sciences, Center for the Soft Matter Science and Engineering, the Key Laboratory of Polymer Chemistry and Physics of the Ministry of Education, College of Chemistry, Peking University, Beijing, China
| | - Xiao Xiao
- Beijing National Laboratory for Molecular Sciences, Center for the Soft Matter Science and Engineering, the Key Laboratory of Polymer Chemistry and Physics of the Ministry of Education, College of Chemistry, Peking University, Beijing, China
| | - Xiao-Ge Wang
- Beijing National Laboratory for Molecular Sciences, Center for the Soft Matter Science and Engineering, the Key Laboratory of Polymer Chemistry and Physics of the Ministry of Education, College of Chemistry, Peking University, Beijing, China
| | - Shang-Da Jiang
- Spin-X Institute, School of Chemistry and Chemical Engineering, State Key Laboratory of Luminescent Materials and Devices, Guangdong-Hong Kong-Macao Joint Laboratory of Optoelectronic and Magnetic Functional Materials, South China University of Technology, Guangzhou, China
| | - Dahui Zhao
- Beijing National Laboratory for Molecular Sciences, Center for the Soft Matter Science and Engineering, the Key Laboratory of Polymer Chemistry and Physics of the Ministry of Education, College of Chemistry, Peking University, Beijing, China
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12
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Abdurahman A, Shen L, Wang J, Niu M, Li P, Peng Q, Wang J, Lu G. A highly efficient open-shell singlet luminescent diradical with strong magnetoluminescence properties. LIGHT, SCIENCE & APPLICATIONS 2023; 12:272. [PMID: 37963871 PMCID: PMC10645991 DOI: 10.1038/s41377-023-01314-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 10/14/2023] [Accepted: 10/23/2023] [Indexed: 11/16/2023]
Abstract
Developing open-shell singlet (OS) diradicals with high luminescent properties and exceptional single-molecule magnetoluminescence (ML) performance is extremely challenging. Herein, we propose a concept to enhance luminescent efficiency by adjusting the donor conjugation of OS diradicals, thereby achieving a highly luminescent diradical, DR1, with outstanding stability and making it a viable option for use in the emitting layer of organic light-emitting diodes (OLEDs). More importantly, the 0.5 wt%-DR1 doped film demonstrates significant single-molecule magnetoluminescence (ML) properties. A giant ML value of 210% is achieved at a magnetic field of 7 T, showing the great potential of DR1 in magneto-optoelectronic devices.
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Affiliation(s)
- Alim Abdurahman
- State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Qianjin Avenue 2699, Changchun, 130012, China.
| | - Li Shen
- College of Chemical Engineering and Environmental Chemistry, Weifang University, Weifang, 261061, China
| | - Jingmin Wang
- Key Laboratory of Flexible Electronics (KLOFE), Institute of Advanced Materials (IAM) & School of Flexible Electronics (Future Technologies), Nanjing Tech University (NanjingTech), 30 South Puzhu Road, Nanjing, 211816, China
| | - Meiling Niu
- Key Laboratory of Flexible Electronics (KLOFE), Institute of Advanced Materials (IAM) & School of Flexible Electronics (Future Technologies), Nanjing Tech University (NanjingTech), 30 South Puzhu Road, Nanjing, 211816, China
| | - Ping Li
- Key Laboratory for Organic Electronics and Information Displays & Institute of Advanced Materials (IAM) National Synergistic Innovation Center for Advanced Materials (SICAM), Nanjing University of Posts & Telecommunications, 9 Wenyuan Road, Nanjing, 210023, China
| | - Qiming Peng
- Key Laboratory of Flexible Electronics (KLOFE), Institute of Advanced Materials (IAM) & School of Flexible Electronics (Future Technologies), Nanjing Tech University (NanjingTech), 30 South Puzhu Road, Nanjing, 211816, China.
| | - Jianpu Wang
- Key Laboratory of Flexible Electronics (KLOFE), Institute of Advanced Materials (IAM) & School of Flexible Electronics (Future Technologies), Nanjing Tech University (NanjingTech), 30 South Puzhu Road, Nanjing, 211816, China
| | - Geyu Lu
- State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Qianjin Avenue 2699, Changchun, 130012, China.
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13
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Pomikło D, Kaszyński P. Blatter Diradicals with a Spin Coupler at the N(1) Position. Chemistry 2023; 29:e202301069. [PMID: 37593967 DOI: 10.1002/chem.202301069] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 05/22/2023] [Accepted: 08/15/2023] [Indexed: 08/19/2023]
Abstract
Reactions of a benzo[e][1,2,4]triazine with dilithiobenzenes lead to di-Blatter diradicals connected at the N(1) positions via a spin coupling unit, 1,4-phenylene or 1,3-phenylene. Electrochemical analysis in MeCN revealed four one-electron redox processes separated by 0.1-0.3 V in both diradicals. Variable temperature EPR measurements in polystyrene (PS) solid solutions gave the singlet-triplet energy gaps ΔES-T =2 J of -3.02(11) and -0.16(1) kcal mol-1 for 1,4-phenylene and 1,3-phenylene derivatives, respectively. The latter negative value was attributed to conformational properties of the diradical in the PS solid solution. Results suggest a simple and efficient access to a family of stable Blatter diradicals with a controllable S-T gap through a judicious choice of the arylene coupling unit. DFT calculations indicate that the triplet state is stabilized by (het)arylenes with low LUMO.
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Affiliation(s)
- Dominika Pomikło
- Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, 90-363, Łódź, Poland
| | - Piotr Kaszyński
- Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, 90-363, Łódź, Poland
- Faculty of Chemistry, University of Łódź, Tamka 12, 91-403, Łódź, Poland
- Department of Chemistry, Middle Tennessee State University, Murfreesboro, TN-37132, USA
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14
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Saha P, Chrysochos N, Elvers BJ, Pätsch S, Uddin SI, Krummenacher I, Nandeshwar M, Mishra A, Raman KV, Rajaraman G, Prabusankar G, Braunschweig H, Ravat P, Schulzke C, Jana A. Bis-Olefin Based Crystalline Schlenk Hydrocarbon Diradicals with a Triplet Ground State. Angew Chem Int Ed Engl 2023; 62:e202311868. [PMID: 37646230 DOI: 10.1002/anie.202311868] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 08/28/2023] [Accepted: 08/28/2023] [Indexed: 09/01/2023]
Abstract
A modular approach for the synthesis of isolable crystalline Schlenk hydrocarbon diradicals from m-phenylene bridged electron-rich bis-triazaalkenes as synthons is reported. EPR spectroscopy confirms their diradical nature and triplet electronic structure by revealing a half-field signal. A computational analysis confirms the triplet state to be the ground state. As a proof-of-principle for the modular methodology, the 4,6-dimethyl-m-phenylene was further utilized as a coupling unit between two alkene motifs. The steric conjunction of the 4,6-dimethyl groups substantially twists the substituents at the nonbonding electron bearing centers relative to the central coupling m-phenylene motif. As a result, the spin delocalization is decreased and the exchange coupling between the two unpaired spins, hence, significantly reduced. Notably, 108 years after Schlenk's m-phenylene-bis(diphenylmethyl) synthesis as a diradical, for the first time we were able to isolate its derivative with the same spacer, i.e. m-phenylene, between two radical centers in a crystalline form.
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Affiliation(s)
- Priyanka Saha
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad, 500046, India
| | - Nicolas Chrysochos
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad, 500046, India
| | - Benedict J Elvers
- Institut für Biochemie, Universität Greifswald, Felix-Hausdorff-Straße 4, 17489, Greifswald, Germany
| | - Sebastian Pätsch
- Institut für Biochemie, Universität Greifswald, Felix-Hausdorff-Straße 4, 17489, Greifswald, Germany
| | - Sk Imraj Uddin
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad, 500046, India
| | - Ivo Krummenacher
- Institute of Inorganic Chemistry and Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Muneshwar Nandeshwar
- Department of Chemistry, Indian Institute of Technology Hyderabad, Kandi, 502284, India
| | - Anshika Mishra
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad, 500046, India
| | - Karthik V Raman
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad, 500046, India
| | - Gopalan Rajaraman
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, 400 076, India
| | - Ganesan Prabusankar
- Department of Chemistry, Indian Institute of Technology Hyderabad, Kandi, 502284, India
| | - Holger Braunschweig
- Institute of Inorganic Chemistry and Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Prince Ravat
- Institute of Organic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Carola Schulzke
- Institut für Biochemie, Universität Greifswald, Felix-Hausdorff-Straße 4, 17489, Greifswald, Germany
| | - Anukul Jana
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad, 500046, India
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15
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Shu C, Yang Z, Rajca A. From Stable Radicals to Thermally Robust High-Spin Diradicals and Triradicals. Chem Rev 2023; 123:11954-12003. [PMID: 37831948 DOI: 10.1021/acs.chemrev.3c00406] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2023]
Abstract
Stable radicals and thermally robust high-spin di- and triradicals have emerged as important organic materials due to their promising applications in diverse fields. New fundamental properties, such as SOMO/HOMO inversion of orbital energies, are explored for the design of new stable radicals, including highly luminescent ones with good photostability. A relation with the singlet-triplet energy gap in the corresponding diradicals is proposed. Thermally robust high-spin di- and triradicals, with energy gaps that are comparable to or greater than a thermal energy at room temperature, are more challenging to synthesize but more rewarding. We summarize a number of high-spin di- and triradicals, based on nitronyl nitroxides that provide a relation between the experimental pairwise exchange coupling constant J/k in the high-spin species vs experimental hyperfine coupling constants in the corresponding monoradicals. This relation allows us to identify outliers, which may correspond to radicals where J/k is not measured with sufficient accuracy. Double helical high-spin diradicals, in which spin density is delocalized over the chiral π-system, have been barely explored, with the sole example of such high-spin diradical possessing alternant π-system with Kekulé resonance form. Finally, we discuss a high-spin diradical with electrical conductivity and derivatives of triangulene diradicals.
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Affiliation(s)
- Chan Shu
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, United States
| | - Zhimin Yang
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, United States
| | - Andrzej Rajca
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, United States
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16
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Abstract
Robust organic triradicals with high-spin quartet ground states provide promising applications in molecular magnets, spintronics, etc. In this context, a triradical based on Blatter's radical has been synthesized recently, having two low-lying non-degenerate doublet states with a quartet ground state. The traditional broken-symmetry (BS)-DFT computed doublet-quartet energy gaps are reported to be somewhat overestimated in comparison to the experimentally observed values. In this work, we have employed different ab initio methods on this prototypical system to obtain more accurate doublet-quartet energy gaps for this triradical. The spin-constraint broken-symmetry (CBS)-DFT method has been used to reduce the overestimation of energy gaps from BS-DFT. To address the issues of spin-contamination and the multireference nature of low-spin states affecting the DFT methods, we have computed the energy gaps using appropriately state-averaged CASSCF and NEVPT2 computations. Using a series of active spaces, our calculations are shown to provide quite accurate values in concordance with the experimentally observed results. Furthermore, we have proposed and modeled another two triradicals based on Blatter's radical, which are of interest for experimental synthesis and characterization. Our computations show that all these triradicals also have a quartet ground state with a similar energy difference between the excited doublet states.
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Affiliation(s)
- Rishu Khurana
- Institute of Nano Science and Technology, Sector-81, Mohali, Punjab 140306, India
| | - Ashima Bajaj
- Institute of Nano Science and Technology, Sector-81, Mohali, Punjab 140306, India
| | - K R Shamasundar
- Indian Institute of Science Education and Research Mohali, Sector-81, Mohali, Punjab 140306, India
| | - Md Ehesan Ali
- Institute of Nano Science and Technology, Sector-81, Mohali, Punjab 140306, India
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17
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Zhang F, Zhang Z, Zhao Y, Du C, Li Y, Gao J, Ren X, Ma T, Li B, Bu Y. Redox-Regulated Magnetic Conversions between Ferro- and Antiferromagnetism in Organic Nitroxide Diradicals. Molecules 2023; 28:6232. [PMID: 37687060 PMCID: PMC10488413 DOI: 10.3390/molecules28176232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 08/07/2023] [Accepted: 08/21/2023] [Indexed: 09/10/2023] Open
Abstract
Redox-induced magnetic transformation in organic diradicals is an appealing phenomenon. In this study, we theoretically designed twelve couples of diradicals in which two nitroxide (NO) radical groups are connected to the redox-active couplers including p-benzoquinonyl, 1,4-naphthoquinyl, 9,10-anthraquinonyl, naphthacene-5,12-dione, pentacene-6,13-dione, hexacene-6,15-dione, pyrazinyl, quinoxalinyl, phenazinyl, 5,12-diazanaphthacene, 6,13-diazapentacene, and 6,15-diazahexacene. As evidenced at both the B3LYP and M06-2X levels of theory, the calculations reveal that the magnetic reversal can take place from ferromagnetism to antiferromagnetism, or vice versa, by means of redox method in these designed organic magnetic molecules. It was observed that p-benzoquinonyl, 1,4-naphthoquinyl, 9,10-anthraquinonyl, naphthacene-5,12-dione, pentacene-6,13-dione, and hexacene-6,15-dione-bridged NO diradicals produce antiferromagnetism while their dihydrogenated counterparts exhibit ferromagnetism. Similarly, pyrazinyl, quinoxalinyl, phenazinyl, 5,12-diazanaphthacene, 6,13-diazapentacene, and 6,15-diazahexacene-bridged NO diradicals present ferromagnetism while their dihydrogenated counterparts show antiferromagnetism. The differences in the magnetic behaviors and magnetic magnitudes of each of the twelve couples of diradicals could be attributed to their distinctly different spin-interacting pathways. It was found that the nature of the coupler and the length of the coupling path are important factors in controlling the magnitude of the magnetic exchange coupling constant J. Specifically, smaller HOMO-LUMO (HOMO: highest occupied molecular orbital, LUMO: lowest unoccupied molecular orbital) gaps of the couplers and shorter coupler lengths, as well as shorter linking bond lengths, can attain stronger magnetic interactions. In addition, a diradical with an extensively π-conjugated structure is beneficial to spin transport and can effectively promote magnetic coupling, yielding a large |J| accordingly. That is, a larger spin polarization can give rise to a stronger magnetic interaction. The sign of J for these studied diradicals can be predicted from the spin alternation rule, the shape of the singly occupied molecular orbitals (SOMOs), and the SOMO-SOMO energy gaps of the triplet state. This study paves the way for the rational design of magnetic molecular switches.
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Affiliation(s)
- Fengying Zhang
- Department of Materials Science and Engineering, Jinzhong University, Jinzhong 030619, China; (C.D.); (Y.L.); (J.G.); (X.R.); (T.M.); (B.L.)
- Shanxi Province Collaborative Innovation Center for Light Materials Modification and Application, Jinzhong 030619, China
| | - Zijun Zhang
- Department of Chemistry and Chemical Engineering, Jinzhong University, Jinzhong 030619, China;
| | - Yali Zhao
- Department of Materials Science and Engineering, Jinzhong University, Jinzhong 030619, China; (C.D.); (Y.L.); (J.G.); (X.R.); (T.M.); (B.L.)
- Shanxi Province Collaborative Innovation Center for Light Materials Modification and Application, Jinzhong 030619, China
| | - Chao Du
- Department of Materials Science and Engineering, Jinzhong University, Jinzhong 030619, China; (C.D.); (Y.L.); (J.G.); (X.R.); (T.M.); (B.L.)
- Shanxi Province Collaborative Innovation Center for Light Materials Modification and Application, Jinzhong 030619, China
| | - Yong Li
- Department of Materials Science and Engineering, Jinzhong University, Jinzhong 030619, China; (C.D.); (Y.L.); (J.G.); (X.R.); (T.M.); (B.L.)
- Shanxi Province Collaborative Innovation Center for Light Materials Modification and Application, Jinzhong 030619, China
| | - Jiaqi Gao
- Department of Materials Science and Engineering, Jinzhong University, Jinzhong 030619, China; (C.D.); (Y.L.); (J.G.); (X.R.); (T.M.); (B.L.)
- Shanxi Province Collaborative Innovation Center for Light Materials Modification and Application, Jinzhong 030619, China
| | - Xiaobo Ren
- Department of Materials Science and Engineering, Jinzhong University, Jinzhong 030619, China; (C.D.); (Y.L.); (J.G.); (X.R.); (T.M.); (B.L.)
- Shanxi Province Collaborative Innovation Center for Light Materials Modification and Application, Jinzhong 030619, China
| | - Teng Ma
- Department of Materials Science and Engineering, Jinzhong University, Jinzhong 030619, China; (C.D.); (Y.L.); (J.G.); (X.R.); (T.M.); (B.L.)
- Shanxi Province Collaborative Innovation Center for Light Materials Modification and Application, Jinzhong 030619, China
| | - Boqiong Li
- Department of Materials Science and Engineering, Jinzhong University, Jinzhong 030619, China; (C.D.); (Y.L.); (J.G.); (X.R.); (T.M.); (B.L.)
- Shanxi Province Collaborative Innovation Center for Light Materials Modification and Application, Jinzhong 030619, China
| | - Yuxiang Bu
- School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, China;
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18
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Abstract
Heteroatom-centered diradical(oid)s have been in the focus of molecular main group chemistry for nearly 30 years. During this time, the diradical concept has evolved and the focus has shifted to the rational design of diradical(oid)s for specific applications. This review article begins with some important theoretical considerations of the diradical and tetraradical concept. Based on these theoretical considerations, the design of diradical(oid)s in terms of ligand choice, steric, symmetry, electronic situation, element choice, and reactivity is highlighted with examples. In particular, heteroatom-centered diradical reactions are discussed and compared with closed-shell reactions such as pericyclic additions. The comparison between closed-shell reactivity, which proceeds in a concerted manner, and open-shell reactivity, which proceeds in a stepwise fashion, along with considerations of diradical(oid) design, provides a rational understanding of this interesting and unusual class of compounds. The application of diradical(oid)s, for example in small molecule activation or as molecular switches, is also highlighted. The final part of this review begins with application-related details of the spectroscopy of diradical(oid)s, followed by an update of the heteroatom-centered diradical(oid)s and tetraradical(oid)s published in the last 10 years since 2013.
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Affiliation(s)
- Alexander Hinz
- Institut für Anorganische Chemie (AOC), Karlsruher Institut für Technologie (KIT), Engesserstrasse 15, 76131 Karlsruhe, Germany
| | - Jonas Bresien
- Institut für Chemie, Universität Rostock, Albert-Einstein-Strasse 3a, 18059 Rostock, Germany
| | - Frank Breher
- Institut für Anorganische Chemie (AOC), Karlsruher Institut für Technologie (KIT), Engesserstrasse 15, 76131 Karlsruhe, Germany
| | - Axel Schulz
- Institut für Chemie, Universität Rostock, Albert-Einstein-Strasse 3a, 18059 Rostock, Germany
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19
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Han H, Huang Y, Tang C, Liu Y, Krzyaniak MD, Song B, Li X, Wu G, Wu Y, Zhang R, Jiao Y, Zhao X, Chen XY, Wu H, Stern CL, Ma Y, Qiu Y, Wasielewski MR, Stoddart JF. Spin-Frustrated Trisradical Trication of PrismCage. J Am Chem Soc 2023; 145:18402-18413. [PMID: 37578165 DOI: 10.1021/jacs.3c04340] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
Organic trisradicals featuring threefold symmetry have attracted significant interest because of their unique magnetic properties associated with spin frustration. Herein, we describe the synthesis and characterization of a triangular prism-shaped organic cage for which we have coined the name PrismCage6+ and its trisradical trication─TR3(•+). PrismCage6+ is composed of three 4,4'-bipyridinium dications and two 1,3,5-phenylene units bridged by six methylene groups. In the solid state, PrismCage6+ adopts a highly twisted conformation with close to C3 symmetry as a result of encapsulating one PF6- anion as a guest. PrismCage6+ undergoes stepwise reduction to its mono-, di-, and trisradical cations in MeCN on account of strong electronic communication between its 4,4'-bipyridinium units. TR3(•+), which is obtained by the reduction of PrismCage6+ employing CoCp2, adopts a triangular prism-shaped conformation with close to C2v symmetry in the solid state. Temperature-dependent continuous-wave and nutation-frequency-selective electron paramagnetic resonance spectra of TR3(•+) in frozen N,N-dimethylformamide indicate its doublet ground state. The doublet-quartet energy gap of TR3(•+) is estimated to be -0.08 kcal mol-1, and the critical temperature of spin-state conversion is found to be ca. 50 K, suggesting that it displays pronounced spin frustration at the molecular level. To the best of our knowledge, this example is the first organic radical cage to exhibit spin frustration. The trisradical trication of PrismCage6+ opens up new possibilities for fundamental investigations and potential applications in the fields of both organic cages and spin chemistry.
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Affiliation(s)
- Han Han
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Yuheng Huang
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Center for Molecular Quantum Transduction, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Institute for Sustainability and Energy at Northwestern, Northwestern University, Evanston, Illinois 60208, United States
| | - Chun Tang
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Yiming Liu
- Beijing National Laboratory for Molecular Sciences, Centre for the Soft Matter Science and Engineering, The Key Lab of Polymer Chemistry & Physics of the Ministry of Education, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Matthew D Krzyaniak
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Center for Molecular Quantum Transduction, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Institute for Sustainability and Energy at Northwestern, Northwestern University, Evanston, Illinois 60208, United States
| | - Bo Song
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Xuesong Li
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Guangcheng Wu
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Yong Wu
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Ruihua Zhang
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Yang Jiao
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Xingang Zhao
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Xiao-Yang Chen
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Huang Wu
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Charlotte L Stern
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Yuguo Ma
- Beijing National Laboratory for Molecular Sciences, Centre for the Soft Matter Science and Engineering, The Key Lab of Polymer Chemistry & Physics of the Ministry of Education, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Yunyan Qiu
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Republic of Singapore
| | - Michael R Wasielewski
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Center for Molecular Quantum Transduction, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Institute for Sustainability and Energy at Northwestern, Northwestern University, Evanston, Illinois 60208, United States
| | - J Fraser Stoddart
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Stoddart Institute of Molecular Science, Department of Chemistry, Zhejiang University, Hangzhou 310027, China
- ZJU-Hangzhou Global Scientific and Technological Innovation Center, Hangzhou 311215, China
- School of Chemistry, University of New South Wales, Sydney, NSW 2052, Australia
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20
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Zhang H, Zou J, Ren X, Li S. Equation-of-Motion Block-Correlated Coupled Cluster Method for Excited Electronic States of Strongly Correlated Systems. J Phys Chem Lett 2023:6792-6799. [PMID: 37478417 DOI: 10.1021/acs.jpclett.3c01474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/23/2023]
Abstract
An equation-of-motion block-correlated coupled cluster method based on the generalized valence bond wave function (EOM-GVB-BCCC) is proposed to describe low-lying excited states for strongly correlated systems. The EOM-GVB-BCCC2b method with up to two-pair correlation has been implemented and tested for a few strongly correlated systems. For a water hexamer with stretched O-H bonds, which is beyond the capability of the CASSCF method, EOM-GVB-BCCC2b provides very close results as the density matrix renormalization group (DMRG). For four conjugated diradical species with triplet ground states, we found that their vertical S-T gaps from EOM-GVB-BCCC2b are also quite consistent with the DMRG results. This new method is expected to be a promising theoretical tool for describing the low-lying excited states of strongly correlated systems with large active spaces.
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Affiliation(s)
- Haodong Zhang
- Key Laboratory of Mesoscopic Chemistry of Ministry of Education, New Cornerstone Science Laboratory, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, People's Republic of China
| | - Jingxiang Zou
- Key Laboratory of Mesoscopic Chemistry of Ministry of Education, New Cornerstone Science Laboratory, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, People's Republic of China
| | - Xiaochuan Ren
- Key Laboratory of Mesoscopic Chemistry of Ministry of Education, New Cornerstone Science Laboratory, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, People's Republic of China
| | - Shuhua Li
- Key Laboratory of Mesoscopic Chemistry of Ministry of Education, New Cornerstone Science Laboratory, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, People's Republic of China
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21
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Yang Z, Pink M, Nowik-Boltyk EM, Lu S, Junghoefer T, Rajca S, Stoll S, Casu MB, Rajca A. Thermally Ultrarobust S = 1/2 Tetrazolinyl Radicals: Synthesis, Electronic Structure, Magnetism, and Nanoneedle Assemblies on Silicon Surface. J Am Chem Soc 2023; 145:13335-13346. [PMID: 37285418 PMCID: PMC10438971 DOI: 10.1021/jacs.3c03402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Open-shell organic molecules, including S = 1/2 radicals, may provide enhanced properties for several emerging technologies; however, relatively few synthesized to date possess robust thermal stability and processability. We report the synthesis of S = 1/2 biphenylene-fused tetrazolinyl radicals 1 and 2. Both radicals possess near-perfect planar structures based on their X-ray structures and density-functional theory (DFT) computations. Radical 1 possesses outstanding thermal stability as indicated by the onset of decomposition at 269 °C, based on thermogravimetric analysis (TGA) data. Both radicals possess very low oxidation potentials <0 V (vs. SCE) and their electrochemical energy gaps, Ecell ≈ 0.9 eV, are rather low. Magnetic properties of polycrystalline 1 are characterized by superconducting quantum interference device (SQUID) magnetometry revealing a one-dimensional S = 1/2 antiferromagnetic Heisenberg chain with exchange coupling constant J'/k ≈ -22.0 K. Radical 1 in toluene glass possesses a long electron spin coherence time, Tm ≈ 7 μs in the 40-80 K temperature range, a property advantageous for potential applications as a molecular spin qubit. Radical 1 is evaporated under ultrahigh vacuum (UHV) forming assemblies of intact radicals on a silicon substrate, as confirmed by high-resolution X-ray photoelectron spectroscopy (XPS). Scanning electron microscope (SEM) images indicate that the radical molecules form nanoneedles on the substrate. The nanoneedles are stable for at least 64 hours under air as monitored by using X-ray photoelectron spectroscopy. Electron paramagnetic resonance (EPR) studies of the thicker assemblies, prepared by UHV evaporation, indicate radical decay according to first-order kinetics with a long half-life of 50 ± 4 days at ambient conditions.
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Affiliation(s)
- Zhimin Yang
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, USA
| | - Maren Pink
- IUMSC, Department of Chemistry, Indiana University, Bloomington, Indiana 47405-7102, USA
| | | | - Shutian Lu
- Department of Chemistry, University of Washington, Seattle, Washington 98195, USA
| | - Tobias Junghoefer
- Institute of Physical and Theoretical Chemistry, University of Tübingen, 72076 Tübingen, Germany
| | - Suchada Rajca
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, USA
| | - Stefan Stoll
- Department of Chemistry, University of Washington, Seattle, Washington 98195, USA
| | - Maria Benedetta Casu
- Institute of Physical and Theoretical Chemistry, University of Tübingen, 72076 Tübingen, Germany
| | - Andrzej Rajca
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, USA
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22
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Boudalis AK, Constantinides CP, Chrysochos N, Carmieli R, Leitus G, Kourtellaris A, Lawson DB, Koutentis PA. Deciphering the ground state of a C 3-symmetrical Blatter-type triradical by CW and pulse EPR spectroscopy. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2023; 349:107406. [PMID: 36841142 DOI: 10.1016/j.jmr.2023.107406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 02/08/2023] [Accepted: 02/13/2023] [Indexed: 06/18/2023]
Abstract
3,3',3''-(Benzene-1,3,5-triyl)tris(1-phenyl-1H-benzo[e][1,2,4]triazin-4-yl) (1) is a C3-symmetrical triradical comprised of three Blatter radical units connected at the 1, 3, 5 positions of a central trimethylenebenzene core. This triradical has an excellent air, moisture, and thermal stability. Single-crystal XRD indicates that triradical 1 adopts a propeller-like geometry with the benzotriazinyl moieties twisted by 174.1(2)° and packs in 1D chains along the c axis to form an extensive network of weak intermolecular interactions. Frozen solution continuous wave (CW) EPR spectra and variable-temperature field-sweep echo-detected (FSED) spectra revealed an intramolecular ferromagnetic exchange within the spin system, supporting a quartet S = 3/2 ground state. DFT calculations further supported these experimental findings.
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Affiliation(s)
- Athanassios K Boudalis
- Institut de Chimie de Strasbourg (UMR 7177, CNRS-Unistra), Université de Strasbourg, 4 rue Blaise Pascal, CS 90032, F-67081 Strasbourg, France.
| | - Christos P Constantinides
- Department of Natural Sciences, University of Michigan - Dearborn, 4901 Evergreen Rd, Dearborn, MI 48128, United States.
| | - Nicolas Chrysochos
- Department of Chemistry, University of Cyprus, P.O. Box 20537, 1678 Nicosia, Cyprus
| | - Raanan Carmieli
- Department of Chemical Research Support, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Gregory Leitus
- Department of Chemical Research Support, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Andreas Kourtellaris
- Department of Chemistry, University of Cyprus, P.O. Box 20537, 1678 Nicosia, Cyprus
| | - Daniel B Lawson
- Department of Natural Sciences, University of Michigan - Dearborn, 4901 Evergreen Rd, Dearborn, MI 48128, United States
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23
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Zhang H, Pink M, Wang Y, Rajca S, Rajca A. High-Spin S = 3/2 Ground-State Aminyl Triradicals: Toward High-Spin Oligo-Aza Nanographenes. J Am Chem Soc 2022; 144:19576-19591. [PMID: 36251959 PMCID: PMC10438970 DOI: 10.1021/jacs.2c09241] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We report high-spin aminyl triradicals with near-planar triphenylene backbones. Near-planarity of the fused aminyl radicals and the 2,6,10-triphenylene ferromagnetic coupling unit (FCU), magnetically equivalent to three fused 3,4'-biphenyl FCUs, assures an effective 2pπ-2pπ overlap within the cross-conjugated π-system, leading to an S = 3/2 (quartet) ground state that is well separated from low-spin excited doublet states. Thermal populations of the low-spin (S = 1/2) excited states are detectable both by SQUID magnetometry and electron paramagnetic resonance (EPR) spectroscopy, providing doublet-quartet energy gaps, ΔEDQ, corresponding to >85% population of the quartet ground states at room temperature. Notably, EPR-based determination of ΔEDQ relies on direct detection of the quartet ground state and doublet excited states. The ΔEDQ values are 1.0-1.1 kcal mol-1, with the more sterically shielded triradical having the larger value. The half-life of the more sterically shielded triradical in 2-methyltetrahydrofuran (2-MeTHF) is about 6 h at room temperature. The less sterically shielded triradical in 2-MeTHF decomposes at 158 K with a half-life of about 4 h, while at 195 K, the half-life is still about 2 h. The dominant products of the decay of triradicals are the corresponding triamines, suggesting hydrogen atom abstraction from the solvent as the primary mechanism. This study expands the frontier of the open-shell PAHs/nanographenes, of which the unique electronic, nonlinear optical, and magnetic properties could be useful in the development of novel organic electronics, photonics, and spintronics.
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Affiliation(s)
- Hui Zhang
- Department of Chemistry, University of Nebraska, Lincoln, NE 68588-0304, United States
| | - Maren Pink
- IUMSC, Department of Chemistry, Indiana University, Bloomington, IN 47405-7102, United States
| | - Ying Wang
- Department of Chemistry, University of Nebraska, Lincoln, NE 68588-0304, United States
| | - Suchada Rajca
- Department of Chemistry, University of Nebraska, Lincoln, NE 68588-0304, United States
| | - Andrzej Rajca
- Department of Chemistry, University of Nebraska, Lincoln, NE 68588-0304, United States
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24
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Sabuj MA, Muoh O, Huda MM, Rai N. Non-Aufbau orbital ordering and spin density modulation in high-spin donor-acceptor conjugated polymers. Phys Chem Chem Phys 2022; 24:23699-23711. [PMID: 36148814 DOI: 10.1039/d2cp02355e] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
High-spin ground-state organic materials with unique spin topology can significantly impact molecular magnetism, spintronics, and quantum computing devices. However, strategies to control the spin topology and alignment of the unpaired spins in different molecular orbitals are not well understood. Here, we report modulating spin distribution along the molecular backbone in high-spin ground-state donor-acceptor (D-A) conjugated polymers. Density functional theory calculations indicate that substitution of different heteroatoms (such as C, Si, N, and Se) alters the aromatic character in the thiadiazole unit of the benzobisthiadiazole (BBT) acceptor and modulates the oligomer length to result in high-spin triplet ground-state, orbital and spin topology. The C, Si, and Se atom substituted polymers show a localized spin density at the two opposite ends of the polymers. However, a delocalized spin distribution is observed in the N substituted polymer. We find that the hybridization (sp3vs. sp2) of the substituent atom plays an important role in controlling the electronic structure of these materials. This study shows that atomistic engineering is an efficient technique to tune the spin topologies and electronic configurations in the high-spin ground-state donor-acceptor conjugated polymers, compelling synthetic targets for room-temperature magnetic materials.
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Affiliation(s)
- Md Abdus Sabuj
- Dave C Swalm School of Chemical Engineering, and Center for Advanced Vehicular Systems, Mississippi State University, Mississippi State, Mississippi, 39762, USA.
| | - Obinna Muoh
- Dave C Swalm School of Chemical Engineering, and Center for Advanced Vehicular Systems, Mississippi State University, Mississippi State, Mississippi, 39762, USA.
| | - Md Masrul Huda
- Dave C Swalm School of Chemical Engineering, and Center for Advanced Vehicular Systems, Mississippi State University, Mississippi State, Mississippi, 39762, USA.
| | - Neeraj Rai
- Dave C Swalm School of Chemical Engineering, and Center for Advanced Vehicular Systems, Mississippi State University, Mississippi State, Mississippi, 39762, USA.
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25
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Kasemthaveechok S, Abella L, Crassous J, Autschbach J, Favereau L. Organic radicals with inversion of SOMO and HOMO energies and potential applications in optoelectronics. Chem Sci 2022; 13:9833-9847. [PMID: 36128246 PMCID: PMC9430691 DOI: 10.1039/d2sc02480b] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Accepted: 07/06/2022] [Indexed: 11/21/2022] Open
Abstract
Organic radicals possessing an electronic configuration in which the energy of the singly occupied molecular orbital (SOMO) is below the highest doubly occupied molecular orbital (HOMO) level have recently attracted significant interest, both theoretically and experimentally. The peculiar orbital energetics of these SOMO-HOMO inversion (SHI) organic radicals set their electronic properties apart from the more common situation where the SOMO is the highest occupied orbital of the system. This review gives a general perspective on SHI, with key fundamental aspects regarding the electronic and structural factors that govern this particular electronic configuration in organic radicals. Selected examples of reported compounds with SHI are highlighted to establish molecular guidelines for designing this type of radical, and to showcase the potential of SHI radicals in organic spintronics as well as for the development of more stable luminescent radicals for OLED applications.
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Affiliation(s)
| | - Laura Abella
- Department of Chemistry, University at Buffalo, State University of New York Buffalo New York 14260 USA
| | | | - Jochen Autschbach
- Department of Chemistry, University at Buffalo, State University of New York Buffalo New York 14260 USA
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26
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Ito S, Yoshitake T, Ishida T. Ferromagnetic 2p-2p and 4f-2p Couplings in a Macrocycle from Two Biradicals and Two Gadolinium(III) Ions. Molecules 2022; 27:molecules27154930. [PMID: 35956880 PMCID: PMC9370185 DOI: 10.3390/molecules27154930] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 07/28/2022] [Accepted: 07/29/2022] [Indexed: 11/25/2022] Open
Abstract
A new ground triplet biradical 2′,4′,6′-triisopropylbiphenyl-3,5-diyl bis(tert-butyl nitroxide) (iPr3BPBN) was prepared and characterized by means of room-temperature ESR spectroscopy displaying a zero-field splitting pattern together with a half-field signal. Complex formation with gadolinium(III) 1,1,1,5,5,5-hexafluoropentane-2,4-dionate (hfac) afforded a macrocycle [{Gd(hfac)3(μ-iPr3BPBN)}2]. As the X-ray crystallographic analysis clarified, the biradical serves as a bridging ligand, giving a 16-membered ring, where each nitroxide radical oxygen atom is directly bonded to a Gd3+ ion. The magnetic study revealed that the iPr3BPBN bridge behaved as a practically triplet biradical and that the Gd3+-radical magnetic coupling was weakly ferromagnetic. The exchange parameters were estimated as 2jrad-rad/kB > 300 K and 2JGd-rad/kB = 1.2 K in the H = −2J S1•S2 convention. The DFT calculation based on the atomic coordinates clarified the ground triplet nature in metal-free iPr3BPBN and the enhanced triplet character upon coordination. The calculation also suggests that ferromagnetic coupling would be favorable when the Gd-O-N-C(sp2) torsion comes around 100°. The present results are compatible with the proposed magneto-structure relationship on the nitroxide-Gd compounds.
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Affiliation(s)
| | | | - Takayuki Ishida
- Correspondence: ; Tel.: +81-42-443-5490; Fax: +81-42-443-5501
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27
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Ito S, Takano R, Hatanaka SI, Ishida T. Rare-Earth (RE = Y, Gd, Tb, Dy, Ho, and Er) Chains Bridged with a Triplet Biradical and Magnetic Hysteresis Recorded for RE = Tb. Inorg Chem 2022; 61:10619-10623. [PMID: 35775974 DOI: 10.1021/acs.inorgchem.2c01107] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Complex formation of 5-tert-butyl-1,3-phenylene bis(tert-butyl nitroxide) and rare-earth (RE) metal ions gave a linear chain where each nitroxide O atom is directly bonded to the RE ion. The bridge was proven to be a ground triplet molecule in the complexes. A hysteresis loop was recorded below 2.8 K as a single-chain magnet for the RE = Tb derivative.
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Affiliation(s)
- Saki Ito
- Department of Engineering Science, The University of Electro-Communications, Chofu, Tokyo 182-8585, Japan
| | - Rina Takano
- Department of Engineering Science, The University of Electro-Communications, Chofu, Tokyo 182-8585, Japan
| | - Shin-Ichi Hatanaka
- Department of Engineering Science, The University of Electro-Communications, Chofu, Tokyo 182-8585, Japan
| | - Takayuki Ishida
- Department of Engineering Science, The University of Electro-Communications, Chofu, Tokyo 182-8585, Japan
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28
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Chen XX, Li JT, Fang YH, Deng XY, Wang XQ, Liu G, Wang Y, Gu X, Jiang SD, Lei T. High-mobility semiconducting polymers with different spin ground states. Nat Commun 2022; 13:2258. [PMID: 35474302 PMCID: PMC9042904 DOI: 10.1038/s41467-022-29918-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 04/05/2022] [Indexed: 12/04/2022] Open
Abstract
Organic semiconductors with high-spin ground states are fascinating because they could enable fundamental understanding on the spin-related phenomenon in light element and provide opportunities for organic magnetic and quantum materials. Although high-spin ground states have been observed in some quinoidal type small molecules or doped organic semiconductors, semiconducting polymers with high-spin at their neutral ground state are rarely reported. Here we report three high-mobility semiconducting polymers with different spin ground states. We show that polymer building blocks with small singlet-triplet energy gap (ΔES-T) could enable small ΔES-T gap and increase the diradical character in copolymers. We demonstrate that the electronic structure, spin density, and solid-state interchain interactions in the high-spin polymers are crucial for their ground states. Polymers with a triplet ground state (S = 1) could exhibit doublet (S = 1/2) behavior due to different spin distributions and solid-state interchain spin-spin interactions. Besides, these polymers showed outstanding charge transport properties with high hole/electron mobilities and can be both n- and p-doped with superior conductivities. Our results demonstrate a rational approach to obtain high-mobility semiconducting polymers with different spin ground states. Semiconducting polymers with high-spin at their neutral ground state are rarely reported. Here the authors synthesize three semiconducting polymers with different spin ground states and high hole/electron mobility, by appropriate choice of the building blocks’ singlet-triplet energy gap, spin distributions and solid-state interchain interactions.
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Affiliation(s)
- Xiao-Xiang Chen
- Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, School of Materials Science and Engineering, Peking University, Beijing, 100871, China.,College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, China
| | - Jia-Tong Li
- Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, School of Materials Science and Engineering, Peking University, Beijing, 100871, China
| | - Yu-Hui Fang
- College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, China
| | - Xin-Yu Deng
- Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, School of Materials Science and Engineering, Peking University, Beijing, 100871, China
| | - Xue-Qing Wang
- Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, School of Materials Science and Engineering, Peking University, Beijing, 100871, China
| | - Guangchao Liu
- Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, School of Materials Science and Engineering, Peking University, Beijing, 100871, China
| | - Yunfei Wang
- School of Polymer Science and Engineering, Center for Optoelectronic Materials and Devices, The University of Southern Mississippi, Hattiesburg, MS, 39406, USA
| | - Xiaodan Gu
- School of Polymer Science and Engineering, Center for Optoelectronic Materials and Devices, The University of Southern Mississippi, Hattiesburg, MS, 39406, USA
| | - Shang-Da Jiang
- Spin-X Institute, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, China
| | - Ting Lei
- Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, School of Materials Science and Engineering, Peking University, Beijing, 100871, China. .,Beijing Key Laboratory for Magnetoelectric Materials and Devices, Peking University, Beijing, 100871, China.
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29
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Zhang S, Pink M, Junghoefer T, Zhao W, Hsu SN, Rajca S, Calzolari A, Boudouris BW, Casu MB, Rajca A. High-Spin ( S = 1) Blatter-Based Diradical with Robust Stability and Electrical Conductivity. J Am Chem Soc 2022; 144:6059-6070. [PMID: 35333507 PMCID: PMC10439714 DOI: 10.1021/jacs.2c01141] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Triplet ground-state organic molecules are of interest with respect to several emerging technologies but usually show limited stability, especially as thin films. We report an organic diradical, consisting of two Blatter radicals, that possesses a triplet ground state with a singlet-triplet energy gap, ΔEST ≈ 0.4-0.5 kcal mol-1 (2J/k ≈ 220-275 K). The diradical possesses robust thermal stability, with an onset of decomposition above 264 °C (TGA). In toluene/chloroform, glassy matrix, and fluid solution, an equilibrium between two conformations with ΔEST ≈ 0.4 kcal mol-1 and ΔEST ≈ -0.7 kcal mol-1 is observed, favoring the triplet ground state over the singlet ground-state conformation in the 110-330 K temperature range. The diradical with the triplet ground-state conformation is found exclusively in crystals and in a polystyrene matrix. The crystalline neutral diradical is a good electrical conductor with conductivity comparable to the thoroughly optimized bis(thiazolyl)-related monoradicals. This is surprising because the triplet ground state implies that the underlying π-system is cross-conjugated and thus is not compatible with either good conductance or electron delocalization. The diradical is evaporated under ultra-high vacuum to form thin films, which are stable in air for at least 18 h, as demonstrated by X-ray photoelectron and electron paramagnetic resonance (EPR) spectroscopies.
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Affiliation(s)
- Shuyang Zhang
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, United States
| | - Maren Pink
- IUMSC, Department of Chemistry, Indiana University, Bloomington, Indiana 47405-7102, United States
| | - Tobias Junghoefer
- Institute of Physical and Theoretical Chemistry, University of Tübingen, 72076 Tübingen, Germany
| | - Wenchao Zhao
- Charles D. Davidson School of Chemical Engineering, Purdue University, West Lafayette, IN 47907, United States
| | - Sheng-Ning Hsu
- Charles D. Davidson School of Chemical Engineering, Purdue University, West Lafayette, IN 47907, United States
| | - Suchada Rajca
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, United States
| | | | - Bryan W. Boudouris
- Charles D. Davidson School of Chemical Engineering, Purdue University, West Lafayette, IN 47907, United States
- Department of Chemistry, Purdue University, West Lafayette, IN 47907, United States
| | - Maria Benedetta Casu
- Institute of Physical and Theoretical Chemistry, University of Tübingen, 72076 Tübingen, Germany
| | - Andrzej Rajca
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, United States
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30
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Kodama T, Aoba M, Hirao Y, Rivero SM, Casado J, Kubo T. Molecular and Spin Structures of a Through‐Space Conjugated Triradical System. Angew Chem Int Ed Engl 2022; 61:e202200688. [DOI: 10.1002/anie.202200688] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Indexed: 12/15/2022]
Affiliation(s)
- Takuya Kodama
- Department of Chemistry, Graduate School of Science Osaka University Toyonaka Osaka 560-0043 Japan
- Current Address: Department of Applied Chemistry Graduate School of Engineering Osaka University Suita Osaka 565-0871 Japan
- Innovative Catalysis Science Division (ICS) Institute for Open and Transdisciplinary Research Initiatives (OTRI) Osaka University Suita Osaka 565-0871 Japan
| | - Mitsuya Aoba
- Department of Chemistry, Graduate School of Science Osaka University Toyonaka Osaka 560-0043 Japan
| | - Yasukazu Hirao
- Department of Chemistry, Graduate School of Science Osaka University Toyonaka Osaka 560-0043 Japan
| | - Samara Medina Rivero
- Department of Physical Chemistry University of Málaga Andalucia-Tech Campus de Teatinos s/n 29071 Málaga Spain
| | - Juan Casado
- Department of Physical Chemistry University of Málaga Andalucia-Tech Campus de Teatinos s/n 29071 Málaga Spain
| | - Takashi Kubo
- Department of Chemistry, Graduate School of Science Osaka University Toyonaka Osaka 560-0043 Japan
- Innovative Catalysis Science Division (ICS) Institute for Open and Transdisciplinary Research Initiatives (OTRI) Osaka University Suita Osaka 565-0871 Japan
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31
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Kodama T, Aoba M, Hirao Y, Rivero SM, Casado J, Kubo T. Molecular and Spin Structures of a Through‐Space Conjugated Triradical System. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202200688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Takuya Kodama
- Osaka University: Osaka Daigaku Department of Applied Chemistry, Graduate School of Engineering JAPAN
| | - Mitsuya Aoba
- Osaka University: Osaka Daigaku Department of Chemistry, Graduate School of Science JAPAN
| | - Yasukazu Hirao
- Osaka University: Osaka Daigaku Department of Chemistry, Graduate School of Science JAPAN
| | - Samara Medina Rivero
- University of Malaga: Universidad de Malaga Department of Physical Chemistry SPAIN
| | - Juan Casado
- University of Malaga: Universidad de Malaga Department of Physical Chemistry SPAIN
| | - Takashi Kubo
- Osaka University: Osaka Daigaku Department of Chemistry, Graduate School of Science 1-1 Machikaneyama 560-0043 Toyonaka JAPAN
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32
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Khurana R, Bajaj A, Ali ME. Tuning the magnetic properties of a diamagnetic di-Blatter's zwitterion to antiferro- and ferromagnetically coupled diradicals. Phys Chem Chem Phys 2022; 24:2543-2553. [PMID: 35024707 DOI: 10.1039/d1cp04807d] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In the quest of obtaining organic molecular magnets based on stable diradicals, we have tuned the inherent zwitterionic ground state of tetraphenylhexaazaanthracene (TPHA), a molecule containing two Blatter's moieties, by adopting two different strategies. In the first strategy, we have increased the length of the coupler between the two radical moieties and observed a transition from the zwitterionic ground state to the diradicalized state. With a larger coupler, ferromagnetic interactions are realized based on density functional theory (DFT) and wave-function theory (WFT) based complete active space self-consistent field (CASSCF)-N-electron valence state perturbation theory (NEVPT2) methods. An analysis based on the extent of spin contamination, diradical character, CASSCF orbital occupation number, Head-Gordon's index, HOMO-LUMO and SOMOs energy gaps is demonstrated that marks the transition of the ground state in these systems. In another approach, we systematically explore the effect of push-pull substitution on the way to obtain molecules based on a TPHA skeleton with diradicaloid state and, in some cases, even a triplet ground state.
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Affiliation(s)
- Rishu Khurana
- Institute of Nano Science and Technology, Sector-81, Mohali, Punjab, 140306, India.
| | - Ashima Bajaj
- Institute of Nano Science and Technology, Sector-81, Mohali, Punjab, 140306, India.
| | - Md Ehesan Ali
- Institute of Nano Science and Technology, Sector-81, Mohali, Punjab, 140306, India.
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33
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Tan Y, Hsu SN, Tahir H, Dou L, Savoie BM, Boudouris BW. Electronic and Spintronic Open-Shell Macromolecules, Quo Vadis? J Am Chem Soc 2022; 144:626-647. [PMID: 34982552 DOI: 10.1021/jacs.1c09815] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Open-shell macromolecules (i.e., polymers containing radical sites either along their backbones or at the pendant sites of repeat units) have attracted significant attention owing to their intriguing chemical and physical (e.g., redox, optoelectronic, and magnetic) properties, and they have been proposed and/or implemented in a wide range of potential applications (e.g., energy storage devices, electronic systems, and spintronic modules). These successes span multiple disciplines that range from advanced macromolecular chemistry through nanoscale structural characterization and on to next-generation solid-state physics and the associated devices. In turn, this has allowed different scientific communities to expand the palette of radical-containing polymers relatively quickly. However, critical gaps remain on many fronts, especially regarding the elucidation of key structure-property-function relationships that govern the underlying electrochemical, optoelectronic, and spin phenomena in these materials systems. Here, we highlight vital developments in the history of open-shell macromolecules to explain the current state of the art in the field. Moreover, we provide a critical review of the successes and bring forward open opportunities that, if solved, could propel this class of materials in a meaningful manner. Finally, we provide an outlook to address where it seems most likely that open-shell macromolecules will go in the coming years. Our considered view is that the future of radical-containing polymers is extremely bright and the addition of talented researchers with diverse skills to the field will allow these materials and their end-use devices to have a positive impact on the global science and technology enterprise in a relatively rapid manner.
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Affiliation(s)
- Ying Tan
- Charles D. Davidson School of Chemical Engineering, Purdue University, 480 Stadium Avenue, West Lafayette, Indiana 47907, United States
| | - Sheng-Ning Hsu
- Charles D. Davidson School of Chemical Engineering, Purdue University, 480 Stadium Avenue, West Lafayette, Indiana 47907, United States
| | - Hamas Tahir
- Charles D. Davidson School of Chemical Engineering, Purdue University, 480 Stadium Avenue, West Lafayette, Indiana 47907, United States
| | - Letian Dou
- Charles D. Davidson School of Chemical Engineering, Purdue University, 480 Stadium Avenue, West Lafayette, Indiana 47907, United States.,Birck Nanotechnology Center, Purdue University, 1205 West State Street, West Lafayette, Indiana 47907, United States
| | - Brett M Savoie
- Charles D. Davidson School of Chemical Engineering, Purdue University, 480 Stadium Avenue, West Lafayette, Indiana 47907, United States
| | - Bryan W Boudouris
- Charles D. Davidson School of Chemical Engineering, Purdue University, 480 Stadium Avenue, West Lafayette, Indiana 47907, United States.,Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
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Tretyakov EV, Ovcharenko VI, Terent'ev AO, Krylov IB, Magdesieva TV, Mazhukin DG, Gritsan NP. Conjugated nitroxide radicals. RUSSIAN CHEMICAL REVIEWS 2022. [DOI: 10.1070/rcr5025] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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35
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Hewitt P, Shultz DA, Kirk ML. Rules for Magnetic Exchange in Azulene-Bridged Biradicals: Quo Vadis? J Org Chem 2021; 86:15577-15587. [PMID: 34644082 DOI: 10.1021/acs.joc.1c02085] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Electronic coupling through organic bridges facilitates magnetic exchange interactions and controls electron transfer and single-molecule device electron transport. Electronic coupling through alternant π-systems (e.g., benzene) is better understood than the corresponding coupling through nonalternant π-systems (e.g., azulene). Herein, we examine the structure, spectroscopy, and magnetic exchange coupling in two biradicals (1,3-SQ2Az and 1,3-SQ-Az-NN; SQ = the zinc(II) complex of spin-1/2 semiquinone radical anion, NN = spin-1/2 nitronylnitroxide; Az = azulene) that possess nonalternant azulene π-system bridges. The SQ radical spin density in both molecules is delocalized into the Az π-system, while the NN spin is effectively localized onto the five-atom ONCNO π-system of NN radical. The spin distributions and interactions are probed by EPR spectroscopy and magnetic susceptibility measurements. We find that J = +38 cm-1 for 1,3-SQ2Az and J = +9 cm-1 for 1,3-SQ-Az-NN (H=-2JS^SQ·S^SQorNN). Our results highlight the differences in exchange coupling mediated by azulene compared to exchange coupling mediated by alternant π-systems.
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Affiliation(s)
- Patrick Hewitt
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
| | - David A Shultz
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
| | - Martin L Kirk
- Department of Chemistry, The University of New Mexico, MSC03 2060, 1 University of New Mexico, Albuquerque, New Mexico 87131-0001, United States
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36
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Prajapati B, Dang D, Chmielewski PJ, Majewski MA, Lis T, Gómez‐García CJ, Zimmerman PM, Stępień M. An Open‐Shell Coronoid with Hybrid Chichibabin–Schlenk Conjugation. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202109273] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Bibek Prajapati
- Wydział Chemii Uniwersytet Wrocławski ul. F. Joliot-Curie 14 50-383 Wrocław Poland
| | - Duy‐Khoi Dang
- Department of Chemistry University of Michigan 930 N. University Ave Ann Arbor MI 48109 USA
| | - Piotr J. Chmielewski
- Wydział Chemii Uniwersytet Wrocławski ul. F. Joliot-Curie 14 50-383 Wrocław Poland
| | - Marcin A. Majewski
- Wydział Chemii Uniwersytet Wrocławski ul. F. Joliot-Curie 14 50-383 Wrocław Poland
| | - Tadeusz Lis
- Wydział Chemii Uniwersytet Wrocławski ul. F. Joliot-Curie 14 50-383 Wrocław Poland
| | - Carlos J. Gómez‐García
- Departamento de Química Inorgánica and Instituto de Ciencia Molecular Universidad de Valencia 46980 Paterna Spain
| | - Paul M. Zimmerman
- Department of Chemistry University of Michigan 930 N. University Ave Ann Arbor MI 48109 USA
| | - Marcin Stępień
- Wydział Chemii Uniwersytet Wrocławski ul. F. Joliot-Curie 14 50-383 Wrocław Poland
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37
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Huang S, Pink M, Ngendahimana T, Rajca S, Eaton GR, Eaton SS, Rajca A. Bis-Spiro-Oxetane and Bis-Spiro-Tetrahydrofuran Pyrroline Nitroxide Radicals: Synthesis and Electron Spin Relaxation Studies. J Org Chem 2021; 86:13636-13643. [PMID: 34546727 PMCID: PMC10441184 DOI: 10.1021/acs.joc.1c01670] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Synthesis of bis-spiro-oxetane and bis-spiro-tetrahydrofuran pyrroline nitroxide radicals relies on the Mitsunobu reaction-mediated double cyclizations of N-Boc protected pyrroline tetraols. Structures of the nitroxide radicals are supported by X-ray crystallography. In a trehalose/sucrose matrix at room temperature, the bis-spiro-oxetane nitroxide radical possesses electron spin coherence time, Tm ≈ 0.7 μs. The observed enhanced Tm is most likely associated with strong hydrogen bonding of oxetane moieties to the trehalose/sucrose matrix.
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Affiliation(s)
- Shengdian Huang
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304
| | - Maren Pink
- IUMSC, Department of Chemistry, Indiana University, Bloomington, Indiana 47405-7102
| | - Thacien Ngendahimana
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80208-2436
| | - Suchada Rajca
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304
| | - Gareth R. Eaton
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80208-2436
| | - Sandra S. Eaton
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80208-2436
| | - Andrzej Rajca
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304
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Stępień M, Prajapati B, Dang DK, Chmielewski PJ, Majewski MA, Lis T, Gómez-García CJ, Zimmerman PM. An Open-Shell Coronoid with Hybrid Chichibabin-Schlenk Conjugation. Angew Chem Int Ed Engl 2021; 60:22496-22504. [PMID: 34382721 DOI: 10.1002/anie.202109273] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 07/30/2021] [Indexed: 11/10/2022]
Abstract
A hexaradicaloid molecule with alternating Kekulé and non-Kekulé connectivities between adjacent spin centers was obtained by fusing two classic conjugation motifs, found respectively in the Chichibabin and Schlenk hydrocarbons, into a coronoid structure. 1 H NMR, ESR and SQUID experiments, combined with computational analyses reveal that the system has a singlet ground state, characterized by a significant hexaradicaloid character ( γ 0 = 0.826, γ 1 = γ 2 = 0.773). It possesses multiple thermally accessible high-spin states (up to the septet), with uniform energy gaps of ca 1.0 kcal/mol between consecutive multiplicities. In line with its open-shell character, the coronoid has a small electronic bandgap of ca. 0.8 eV and undergoes two consecutive one-electron oxidations at low potentials, yielding cationic forms with extended near-infrared absorption. The hexaradicaloid, which combines open-shell and macrocyclic contributions to its π conjugation, provides an example of a design strategy for multistate spin switches and redox-amphoteric NIR dyes.
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Affiliation(s)
- Marcin Stępień
- University of Wroclaw, Department of Chemistry, ul. F. Joliot-Curie 14, 50-383, Wroclaw, POLAND
| | | | - Duy-Khoi Dang
- University of Michigan Ann Arbor, Department of Chemistry, UNITED STATES
| | | | | | - Tadeusz Lis
- Uniwersytet Wrocławski, Wydział Chemii, POLAND
| | - Carlos J Gómez-García
- Universidad de Valencia, Departamento de Química Inorgánica and Instituto de Ciencia Molecular, SPAIN
| | - Paul M Zimmerman
- University of Michigan Ann Arbor, Department of Chemistry, UNITED STATES
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39
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Cui H, Hu ZB, Chen C, Ruan H, Fang Y, Zhang L, Zhao Y, Tan G, Song Y, Wang X. A high-spin diradical dianion and its bridged chemically switchable single-molecule magnet. Chem Sci 2021; 12:9998-10004. [PMID: 34377394 PMCID: PMC8317668 DOI: 10.1039/d1sc01932e] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Accepted: 06/21/2021] [Indexed: 11/21/2022] Open
Abstract
Triplet diradicals have attracted tremendous attention due to their promising application in organic spintronics, organic magnets and spin filters. However, very few examples of triplet diradicals with singlet–triplet energy gaps (ΔEST) over 0.59 kcal mol−1 (298 K) have been reported to date. In this work, we first proved that the dianion of 2,7-di-tert-butyl-pyrene-4,5,9,10-tetraone (2,7-tBu2-PTO) was a triplet ground state diradical in the magnesium complex 1 with a singlet–triplet energy gap ΔEST = 0.94 kcal mol−1 (473 K). This is a rare example of stable diradicals with singlet–triplet energy gaps exceeding the thermal energy at room temperature (298 K). Moreover, the iron analog 2 containing the 2,7-tBu2-PTO diradical dianion was isolated, which was the first single-molecule magnet bridged by a diradical dianion. When 2 was doubly reduced to the dianion salt 2K2, single-molecule magnetism was switched off, highlighting the importance of diradicals in single-molecule magnetism. We report a triplet diradical dianion in magnesium complex with ΔEST = 0.94 kcal mol−1 (473 K). Its iron analog is the first single-molecule magnet bridged by a diradical dianion, and the SMM property is switched off through two-electron reduction.![]()
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Affiliation(s)
- Haiyan Cui
- State Key Laboratory of Coordination Chemistry, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University Nanjing 210023 China .,Jiangsu Key Laboratory of Pesticide Science, College of Sciences, Nanjing Agricultural University Nanjing 210095 China
| | - Zhao-Bo Hu
- State Key Laboratory of Coordination Chemistry, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University Nanjing 210023 China
| | - Chao Chen
- State Key Laboratory of Coordination Chemistry, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University Nanjing 210023 China
| | - Huapeng Ruan
- State Key Laboratory of Coordination Chemistry, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University Nanjing 210023 China
| | - Yong Fang
- State Key Laboratory of Coordination Chemistry, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University Nanjing 210023 China
| | - Li Zhang
- Center of Materials Science and Engineering, Guangxi University of Science and Technology Liuzhou 545006 China
| | - Yue Zhao
- State Key Laboratory of Coordination Chemistry, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University Nanjing 210023 China
| | - Gengwen Tan
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University Suzhou 215123 China
| | - You Song
- State Key Laboratory of Coordination Chemistry, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University Nanjing 210023 China
| | - Xinping Wang
- State Key Laboratory of Coordination Chemistry, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University Nanjing 210023 China
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40
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Tretyakov EV, Petunin PV, Zhivetyeva SI, Gorbunov DE, Gritsan NP, Fedin MV, Stass DV, Samoilova RI, Bagryanskaya IY, Shundrina IK, Bogomyakov AS, Kazantsev MS, Postnikov PS, Trusova ME, Ovcharenko VI. Platform for High-Spin Molecules: A Verdazyl-Nitronyl Nitroxide Triradical with Quartet Ground State. J Am Chem Soc 2021; 143:8164-8176. [PMID: 34019759 DOI: 10.1021/jacs.1c02938] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Thermally resistant air-stable organic triradicals with a quartet ground state and a large energy gap between spin states are still unique compounds. In this work, we succeeded to design and prepare the first highly stable triradical, consisting of oxoverdazyl and nitronyl nitroxide radical fragments, with a quartet ground state. The triradical and its diradical precursor were synthesized via a palladium-catalyzed cross-coupling reaction of diiodoverdazyl with nitronyl nitroxide-2-ide gold(I) complex. Both paramagnetic compounds were fully characterized by single-crystal X-ray diffraction analysis, superconducting quantum interference device magnetometry, EPR spectroscopy in various matrices, and cyclic voltammetry. In the diradical, the verdazyl and nitronyl nitroxide centers demonstrated full reversibility of redox process, while for the triradical, the electrochemical reduction and oxidation proceed at practically the same redox potentials, but become quasi-reversible. A series of high-level CASSCF/NEVPT2 calculations was performed to predict inter- and intramolecular exchange interactions in crystals of di- and triradicals and to establish their magnetic motifs. Based on the predicted magnetic motifs, the temperature dependences of the magnetic susceptibility were analyzed, and the singlet-triplet (135 ± 10 cm-1) and doublet-quartet (17 ± 2 and 152 ± 19 cm-1) splitting was found to be moderate. Unique high stability of synthesized verdazyl-nitronylnitroxide triradical opens new perspectives for further functionalization and design of high-spin systems with four or more spins.
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Affiliation(s)
- Evgeny V Tretyakov
- N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Ave. 47, Moscow 119991, Russian Federation
| | - Pavel V Petunin
- Tomsk Polytechnic University, Lenin Ave. 30, Tomsk 634050, Russian Federation
| | - Svetlana I Zhivetyeva
- N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry, Siberian Branch of Russian Academy of Sciences, Ac. Lavrentiev Ave. 9, Novosibirsk 630090, Russian Federation
| | - Dmitry E Gorbunov
- V.V. Voevodsky Institute of Chemical Kinetics and Combustion, Siberian Branch of Russian Academy of Sciences, Institutskaya Str. 3, Novosibirsk 630090, Russian Federation
| | - Nina P Gritsan
- V.V. Voevodsky Institute of Chemical Kinetics and Combustion, Siberian Branch of Russian Academy of Sciences, Institutskaya Str. 3, Novosibirsk 630090, Russian Federation
| | - Matvey V Fedin
- International Tomography Center, Siberian Branch of Russian Academy of Sciences, Institutskaya Str. 3a, Novosibirsk 630090, Russian Federation
| | - Dmitri V Stass
- V.V. Voevodsky Institute of Chemical Kinetics and Combustion, Siberian Branch of Russian Academy of Sciences, Institutskaya Str. 3, Novosibirsk 630090, Russian Federation.,Novosibirsk State University, Pirogova Str. 2, Novosibirsk 630090, Russian Federation
| | - Rimma I Samoilova
- V.V. Voevodsky Institute of Chemical Kinetics and Combustion, Siberian Branch of Russian Academy of Sciences, Institutskaya Str. 3, Novosibirsk 630090, Russian Federation
| | - Irina Yu Bagryanskaya
- N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry, Siberian Branch of Russian Academy of Sciences, Ac. Lavrentiev Ave. 9, Novosibirsk 630090, Russian Federation
| | - Inna K Shundrina
- N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry, Siberian Branch of Russian Academy of Sciences, Ac. Lavrentiev Ave. 9, Novosibirsk 630090, Russian Federation
| | - Artem S Bogomyakov
- International Tomography Center, Siberian Branch of Russian Academy of Sciences, Institutskaya Str. 3a, Novosibirsk 630090, Russian Federation
| | - Maxim S Kazantsev
- N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry, Siberian Branch of Russian Academy of Sciences, Ac. Lavrentiev Ave. 9, Novosibirsk 630090, Russian Federation
| | - Pavel S Postnikov
- Tomsk Polytechnic University, Lenin Ave. 30, Tomsk 634050, Russian Federation
| | - Marina E Trusova
- Tomsk Polytechnic University, Lenin Ave. 30, Tomsk 634050, Russian Federation
| | - Victor I Ovcharenko
- International Tomography Center, Siberian Branch of Russian Academy of Sciences, Institutskaya Str. 3a, Novosibirsk 630090, Russian Federation
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41
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Bajaj A, Khurana R, Ali ME. Auxiliary Atomic Relay Center Facilitates Enhanced Magnetic Couplings in Blatter's Radical. J Phys Chem A 2021; 125:4133-4142. [PMID: 33949868 DOI: 10.1021/acs.jpca.1c02198] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The recent accomplishments in obtaining strong ferromagnetic exchange interactions in organic diradicals have made the field quite fascinating and even more promising toward its technological applications. In this context, herein, we report a unique combination of remarkably strong ferromagnetic exchange interactions coupled with molecular rigidity, utilizing superstable Blatter's radical as a spin source. The planar analogues of the parent Blatter's radical obtained by annulation with a chalcogen coupled to nitronyl nitroxide (NN) are investigated using density functional theory along with the wave function-based multiconfigurational self-consistent field methods, for example, complete active space self-consistent field (CASSCF)-N-electron valence state perturbation theory (NEVPT2). The calculations reveal phenomenal modulation in exchange couplings upon annulation such that remarkably strong ferromagnetic interactions are realized especially for a certain class of the Blatter-NN diradicals. The modulation of spin-spin interactions is rationalized by variation in spin density distribution and molecular torsional angles. We demonstrate that annulation in OMMs opens an additional coupling pathway via auxiliary X-atom acting as the atomic relay center which strongly manipulates the magnitude of exchange couplings.
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Affiliation(s)
- Ashima Bajaj
- Institute of Nano Science and Technology, Sector-81, Mohali, Punjab 140306, India
| | - Rishu Khurana
- Institute of Nano Science and Technology, Sector-81, Mohali, Punjab 140306, India
| | - Md Ehesan Ali
- Institute of Nano Science and Technology, Sector-81, Mohali, Punjab 140306, India
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42
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Miyazawa Y, Wang Z, Matsumoto M, Hatano S, Antol I, Kayahara E, Yamago S, Abe M. 1,3-Diradicals Embedded in Curved Paraphenylene Units: Singlet versus Triplet State and In-Plane Aromaticity. J Am Chem Soc 2021; 143:7426-7439. [PMID: 33900091 DOI: 10.1021/jacs.1c01329] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Curved π-conjugated molecules and open-shell structures have attracted much attention from the perspective of fundamental chemistry, as well as materials science. In this study, the chemistry of 1,3-diradicals (DRs) embedded in curved cycloparaphenylene (CPPs) structures, DR-(n+3)CPPs (n = 0-5), was investigated to understand the effects of the curvature and system size on the spin-spin interactions and singlet versus triplet state, as well as their unique characteristics such as in-plane aromaticity. A triplet ground state was predicted for the larger 1,3-diradicals, such as the seven- and eight-paraphenylene-unit-containing diradicals DR-7CPP (n = 4) and DR-8CPP (n = 5), by quantum chemical calculations. The smaller-sized diradicals DR-(n+3)CPPs (n = 0-3) were found to possess singlet ground states. Thus, the ground-state spin multiplicity is controlled by the size of the paraphenylene cycle. The size effect on the ground-state spin multiplicity was confirmed by the experimental generation of DR-6CPP in the photochemical denitrogenation of its azo-containing precursor (AZ-6CPP). Intriguingly, a unique type of in-plane aromaticity emerged in the smaller-sized singlet states such as S-DR-4CPP (n = 1), as proven by nucleus-independent chemical shift calculations (NICS) and an analysis of the anisotropy of the induced current density (ACID), which demonstrate that homoconjugation between the 1,3-diradical moiety arises because of the curved and distorted bonding system.
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Affiliation(s)
- Yuki Miyazawa
- Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Zhe Wang
- Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Misaki Matsumoto
- Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Sayaka Hatano
- Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Ivana Antol
- Laboratory for Physical Organic Chemistry, Division of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia
| | - Eiichi Kayahara
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Shigeru Yamago
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Manabu Abe
- Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
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43
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Shu C, Pink M, Junghoefer T, Nadler E, Rajca S, Casu MB, Rajca A. Synthesis and Thin Films of Thermally Robust Quartet ( S = 3/2) Ground State Triradical. J Am Chem Soc 2021; 143:5508-5518. [PMID: 33787241 DOI: 10.1021/jacs.1c01305] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
High-spin (S = 3/2) organic triradicals may offer enhanced properties with respect to several emerging technologies, but those synthesized to date typically exhibit small doublet quartet energy gaps and/or possess limited thermal stability and processability. We report a quartet ground state triradical 3, synthesized by a Pd(0)-catalyzed radical-radical cross-coupling reaction, which possesses two doublet-quartet energy gaps, ΔEDQ ≈ 0.2-0.3 kcal mol-1 and ΔEDQ2 ≈ 1.2-1.8 kcal mol-1. The triradical has a 70+% population of the quartet ground state at room temperature and good thermal stability with onset of decomposition at >160 °C under an inert atmosphere. Magnetic properties of 3 are characterized by SQUID magnetometry in polystyrene glass and by quantitative EPR spectroscopy. Triradical 3 is evaporated under ultrahigh vacuum to form thin films of intact triradicals on silicon substrate, as confirmed by high-resolution X-ray photoelectron spectroscopy. AFM and SEM images of the ∼1 nm thick films indicate that the triradical molecules form islands on the substrate. The films are stable under ultrahigh vacuum for at least 17 h but show onset of decomposition after 4 h at ambient conditions. The drop-cast films are less prone to degradation in air and have a longer lifetime.
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Affiliation(s)
- Chan Shu
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, United States
| | - Maren Pink
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405-7102, United States
| | - Tobias Junghoefer
- Institute of Physical and Theoretical Chemistry, University of Tübingen, 72076 Tübingen, Germany
| | - Elke Nadler
- Institute of Physical and Theoretical Chemistry, University of Tübingen, 72076 Tübingen, Germany
| | - Suchada Rajca
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, United States
| | - Maria Benedetta Casu
- Institute of Physical and Theoretical Chemistry, University of Tübingen, 72076 Tübingen, Germany
| | - Andrzej Rajca
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, United States
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44
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Wang K, Liu P, Zhang F, Xu L, Zhou M, Nakai A, Kato K, Furukawa K, Tanaka T, Osuka A, Song J. A Robust Porphyrin-Stabilized Triplet Carbon Diradical. Angew Chem Int Ed Engl 2021; 60:7002-7006. [PMID: 33393192 DOI: 10.1002/anie.202015356] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 12/25/2020] [Indexed: 11/06/2022]
Abstract
The synthesis of robust high-spin carbon radicals is an important topic in organic chemistry. Toward this end, several porphyrin-stabilized radicals have been systematically explored. A singly naphthalene-fused porphyrin radical was synthesized by a reaction sequence consisting of a Suzuki-Miyaura coupling of β-borylated porphyrin with 2-bromobenzaldehyde, addition of mesityl Grignard reagent, intramolecular Friedel-Crafts alkylation, and final oxidation with DDQ or tBuOK/O2 . This strategy was also used to synthesize doubly naphthalene-fused porphyrins and syn- and anti-fused-anthracene-bridged porphyrin dimers. While singly naphthalene-fused porphyrin radical has been shown to be a stable monoradical, doubly naphthalene-fused porphyrins and anti-fused-anthracene-bridged porphyrin dimers have been shown to be closed-shell molecules. Finally, the syn-dimer was characterized as a surprisingly stable radical (t1/2 =28 days under ambient air and at 80 °C) that is storable for more than several months, despite its high-spin triplet ground-state carbon diradical.
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Affiliation(s)
- Kaisheng Wang
- College of Chemistry and Chemical Engineering, Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education of China), Key Laboratory of the Assembly and Application of Organic Functional molecules of Hunan Province, Hunan Normal University, Changsha, 410081, China
| | - Pingting Liu
- College of Chemistry and Chemical Engineering, Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education of China), Key Laboratory of the Assembly and Application of Organic Functional molecules of Hunan Province, Hunan Normal University, Changsha, 410081, China
| | - Fenni Zhang
- College of Chemistry and Chemical Engineering, Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education of China), Key Laboratory of the Assembly and Application of Organic Functional molecules of Hunan Province, Hunan Normal University, Changsha, 410081, China
| | - Ling Xu
- College of Chemistry and Chemical Engineering, Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education of China), Key Laboratory of the Assembly and Application of Organic Functional molecules of Hunan Province, Hunan Normal University, Changsha, 410081, China
| | - Mingbo Zhou
- College of Chemistry and Chemical Engineering, Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education of China), Key Laboratory of the Assembly and Application of Organic Functional molecules of Hunan Province, Hunan Normal University, Changsha, 410081, China
| | - Akito Nakai
- Department of Chemistry, Graduate School of Science Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan
| | - Kenichi Kato
- Department of Chemistry, Graduate School of Science Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan
| | - Ko Furukawa
- Center for Instrumental Analysis, Niigata University, Nishi-ku, Niigata, 950-2181, Japan
| | - Takayuki Tanaka
- Department of Chemistry, Graduate School of Science Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan
| | - Atsuhiro Osuka
- College of Chemistry and Chemical Engineering, Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education of China), Key Laboratory of the Assembly and Application of Organic Functional molecules of Hunan Province, Hunan Normal University, Changsha, 410081, China
| | - Jianxin Song
- College of Chemistry and Chemical Engineering, Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education of China), Key Laboratory of the Assembly and Application of Organic Functional molecules of Hunan Province, Hunan Normal University, Changsha, 410081, China
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45
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Wang K, Liu P, Zhang F, Xu L, Zhou M, Nakai A, Kato K, Furukawa K, Tanaka T, Osuka A, Song J. A Robust Porphyrin‐Stabilized Triplet Carbon Diradical. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202015356] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Kaisheng Wang
- College of Chemistry and Chemical Engineering Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education of China) Key Laboratory of the Assembly and Application of Organic Functional molecules of Hunan Province Hunan Normal University Changsha 410081 China
| | - Pingting Liu
- College of Chemistry and Chemical Engineering Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education of China) Key Laboratory of the Assembly and Application of Organic Functional molecules of Hunan Province Hunan Normal University Changsha 410081 China
| | - Fenni Zhang
- College of Chemistry and Chemical Engineering Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education of China) Key Laboratory of the Assembly and Application of Organic Functional molecules of Hunan Province Hunan Normal University Changsha 410081 China
| | - Ling Xu
- College of Chemistry and Chemical Engineering Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education of China) Key Laboratory of the Assembly and Application of Organic Functional molecules of Hunan Province Hunan Normal University Changsha 410081 China
| | - Mingbo Zhou
- College of Chemistry and Chemical Engineering Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education of China) Key Laboratory of the Assembly and Application of Organic Functional molecules of Hunan Province Hunan Normal University Changsha 410081 China
| | - Akito Nakai
- Department of Chemistry Graduate School of Science Kyoto University Sakyo-ku Kyoto 606-8502 Japan
| | - Kenichi Kato
- Department of Chemistry Graduate School of Science Kyoto University Sakyo-ku Kyoto 606-8502 Japan
| | - Ko Furukawa
- Center for Instrumental Analysis Niigata University Nishi-ku Niigata 950-2181 Japan
| | - Takayuki Tanaka
- Department of Chemistry Graduate School of Science Kyoto University Sakyo-ku Kyoto 606-8502 Japan
| | - Atsuhiro Osuka
- College of Chemistry and Chemical Engineering Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education of China) Key Laboratory of the Assembly and Application of Organic Functional molecules of Hunan Province Hunan Normal University Changsha 410081 China
| | - Jianxin Song
- College of Chemistry and Chemical Engineering Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education of China) Key Laboratory of the Assembly and Application of Organic Functional molecules of Hunan Province Hunan Normal University Changsha 410081 China
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46
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Rausch R, Krause AM, Krummenacher I, Braunschweig H, Würthner F. Nitronyl Nitroxide Bifunctionalized Electron-Poor Chromophores: Synthesis of Stable Dye Biradicals by Lewis Acid Promoted Desilylation. J Org Chem 2021; 86:2447-2457. [PMID: 33434018 DOI: 10.1021/acs.joc.0c02613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Open shell organic molecules bearing π-cores are of great interest for optical, electronic, and magnetic applications but frequently suffer fast decomposition or lack synthetic accessibility. In this regard, nitronyl nitroxides are promising candidates for stable (bi-)radicals due to their high degree of spin delocalization along the O-N-C-N-O pentad unit. Unfortunately, they are limited to electron-rich systems so far. To overcome this limitation, we developed a synthetic procedure for the twofold spin decoration of electron-poor chromophores (Ered = -1158 mV) with nitronyl nitroxide radical moieties via selective deprotection/oxidation of the respective silylated precursors with boron fluoride and subsequent quenching with tetraethyl orthosilicate. Nitronyl nitroxide biradicals PBI-NN, IIn-NN, PhDPP-NN, ThDPP-NN, and FuDPP-NN bridged by perylene bisimide (PBI), isoindigo (IIn), and diketopyrrolopyrrole (DPP) pigment colorants were finally obtained as bench stable compounds after periodate oxidation with yields of 60-81%. The absorption spectral signatures of the chromophores remain preserved in the open shell state and match the ones of the pristine parent compounds, which allowed an a priori prediction of their optical properties. Consequently, we achieved twofold spin labeling while keeping the intrinsic properties of the electron deficient chromophores intact.
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Affiliation(s)
- Rodger Rausch
- Institut für Organische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Ana-Maria Krause
- Institut für Organische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.,Center for Nanosystems Chemistry (CNC), Universität Würzburg, Theodor-Boveri-Weg, 97074 Würzburg, Germany
| | - Ivo Krummenacher
- Institut für Anorganische Chemie and Institute for Sustainable Chemistry and Catalysis with Boron, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Holger Braunschweig
- Institut für Anorganische Chemie and Institute for Sustainable Chemistry and Catalysis with Boron, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Frank Würthner
- Institut für Organische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.,Center for Nanosystems Chemistry (CNC), Universität Würzburg, Theodor-Boveri-Weg, 97074 Würzburg, Germany
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47
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Molecular S = 2 High-Spin, S = 0 Low-Spin and S = 0 ⇄ 2 Spin-Transition/-Crossover Nickel(II)-Bis(nitroxide) Coordination Compounds. INORGANICS 2021. [DOI: 10.3390/inorganics9020010] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Heterospin systems have a great advantage in frontier orbital engineering since they utilize a wide diversity of paramagnetic chromophores and almost infinite combinations and mutual geometries. Strong exchange couplings are expected in 3d–2p heterospin compounds, where the nitroxide (aminoxyl) oxygen atom has a direct coordination bond with a nickel(II) ion. Complex formation of nickel(II) salts and tert-butyl 2-pyridyl nitroxides afforded a discrete 2p–3d–2p triad. Ferromagnetic coupling is favored when the magnetic orbitals, nickel(II) dσ and radical π*, are arranged in a strictly orthogonal fashion, namely, a planar coordination structure is characterized. In contrast, a severe twist around the coordination bond gives an orbital overlap, resulting in antiferromagnetic coupling. Non-chelatable nitroxide ligands are available for highly twisted and practically diamagnetic complexes. Here, the Ni–O–N–Csp2 torsion (dihedral) angle is supposed to be a useful metric to describe the nickel ion dislocated out of the radical π* nodal plane. Spin-transition complexes exhibited a planar coordination structure in a high-temperature phase and a nonplanar structure in a low-temperature phase. The gradual spin transition is described as a spin equilibrium obeying the van’t Hoff law. Density functional theory calculation indicates that the energy level crossing of the high- and low-spin states. The optimized structures of diamagnetic and high-spin states well agreed with the experimental large and small torsions, respectively. The novel mechanism of the present spin transition lies in the ferro-/antiferromagnetic coupling switch. The entropy-driven mechanism is plausible after combining the results of the related copper(II)-nitroxide compounds. Attention must be paid to the coupling parameter J as a variable of temperature in the magnetic analysis of such spin-transition materials. For future work, the exchange coupling may be tuned by chemical modification and external stimulus, because it has been clarified that the parameter is sensitive to the coordination structure and actually varies from 2J/kB = +400 K to −1400 K.
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48
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Chapyshev SV, Korchagin DV, Misochko EY. Recent advances in chemistry of high-spin nitrenes. RUSSIAN CHEMICAL REVIEWS 2021. [DOI: 10.1070/rcr4965] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Experimental and theoretical studies on aromatic nitrenes bearing from three to six unpaired electrons and having quartet, quintet, sextet or septet ground spin states, published in the last 15 years are analyzed. A comparative analysis of the magnetic properties of high-spin nitrenes and all other known high-spin organic molecules is performed. Promising areas of practical application of high-spin nitrenes as molecular magnets and as qubits and qudits for quantum computations are discussed.
The bibliography includes 214 references.
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49
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Magnan F, Dhindsa JS, Anghel M, Bazylewski P, Fanchini G, Gilroy JB. A divergent strategy for the synthesis of redox-active verdazyl radical polymers. Polym Chem 2021. [DOI: 10.1039/d1py00217a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
We describe a divergent synthetic strategy based on ATRP and CuAAC chemistry for the production of stable radical polymers. As a proof of concept, we prepare verdazyl radical polymers with properties suitable for use in organic electronics.
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Affiliation(s)
- François Magnan
- Department of Chemistry
- The University of Western Ontario
- London
- Canada
- The Centre for Advanced Materials and Biomaterials Research (CAMBR)
| | - Jasveer S. Dhindsa
- Department of Chemistry
- The University of Western Ontario
- London
- Canada
- The Centre for Advanced Materials and Biomaterials Research (CAMBR)
| | - Michael Anghel
- Department of Chemistry
- The University of Western Ontario
- London
- Canada
- The Centre for Advanced Materials and Biomaterials Research (CAMBR)
| | - Paul Bazylewski
- The Centre for Advanced Materials and Biomaterials Research (CAMBR)
- The University of Western Ontario
- London
- Canada
- Department of Physics and Astronomy
| | - Giovanni Fanchini
- Department of Chemistry
- The University of Western Ontario
- London
- Canada
- The Centre for Advanced Materials and Biomaterials Research (CAMBR)
| | - Joe B. Gilroy
- Department of Chemistry
- The University of Western Ontario
- London
- Canada
- The Centre for Advanced Materials and Biomaterials Research (CAMBR)
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50
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Kasemthaveechok S, Abella L, Jean M, Cordier M, Roisnel T, Vanthuyne N, Guizouarn T, Cador O, Autschbach J, Crassous J, Favereau L. Axially and Helically Chiral Cationic Radical Bicarbazoles: SOMO-HOMO Level Inversion and Chirality Impact on the Stability of Mono- and Diradical Cations. J Am Chem Soc 2020; 142:20409-20418. [PMID: 33201694 DOI: 10.1021/jacs.0c08948] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
We report persistent chiral organic mono- and diradical cations based on bicarbazole molecular design with an unprecedented stability dependence on the type of chirality, namely, axial versus helical. An unusual chemical stability was observed for sterically unprotected axial bicarbazole radical in comparison with monocarbazole and helical bicarbazole ones. Such results were experimentally and theoretically investigated, revealing an inversion in energy of the singly occupied molecular orbital (SOMO) and the highest (doubly) occupied molecular orbital (HOMO) in both axial and helical bicarbazole monoradicals along with a subtle difference of electronic coupling between the two carbazole units, which is modulated by their relative dihedral angle and related to the type of chirality. Such findings allowed us to explore in depth the SOMO-HOMO inversion (SHI) in chiral radical molecular systems and provide new insights regarding its impact on the stability of organic radicals. Finally, these specific electronic properties allowed us to prepare a persistent, intrinsically chiral, diradical which notably displayed near-infrared electronic circular dichroism responses up to 1100 nm and almost degenerate singlet-triplet ground states with weak antiferromagnetic interactions evaluated by magnetometry experiments.
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Affiliation(s)
| | - Laura Abella
- Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260, United States
| | - Marion Jean
- Aix Marseille University, CNRS Centrale Marseille, iSm2, Marseille 13284, France
| | - Marie Cordier
- Université Rennes, CNRS, ISCR-UMR 6226, Rennes F-35000, France
| | - Thierry Roisnel
- Université Rennes, CNRS, ISCR-UMR 6226, Rennes F-35000, France
| | - Nicolas Vanthuyne
- Aix Marseille University, CNRS Centrale Marseille, iSm2, Marseille 13284, France
| | | | - Olivier Cador
- Université Rennes, CNRS, ISCR-UMR 6226, Rennes F-35000, France
| | - Jochen Autschbach
- Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260, United States
| | - Jeanne Crassous
- Université Rennes, CNRS, ISCR-UMR 6226, Rennes F-35000, France
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