1
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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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2
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Wei D, Qin Y, Xu Z, Liu H, Chen R, Yu Y, Wang D. Study of Molecular Dimer Morphology Based on Organic Spin Centers: Nitronyl Nitroxide Radicals. Molecules 2024; 29:2042. [PMID: 38731533 PMCID: PMC11085200 DOI: 10.3390/molecules29092042] [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: 03/25/2024] [Revised: 04/24/2024] [Accepted: 04/27/2024] [Indexed: 05/13/2024] Open
Abstract
In this work, in order to investigate the short-range interactions between molecules, the spin-magnetic unit nitronyl nitroxide (NN) was introduced to synthesize self-assembly single radical molecules with hydrogen bond donors and acceptors. The structures and magnetic properties were extensively investigated and characterized by UV-Vis absorption spectroscopy, electron paramagnetic resonance (EPR), and superconducting quantum interference devices (SQUIDs). Interestingly, it was observed that the single molecules can form two different dimers (ring-closed dimer and "L"-type dimer) in different solvents, due to hydrogen bonding, when using EPR to track the molecular spin interactions. Both dimers exhibit ferromagnetic properties (for ring-closed dimer, J/kB = 0.18 K and ΔES-T = 0.0071 kcal/mol; for "L"-type dimer, the values were J/kB = 9.26 K and ΔES-T = 0.037 kcal/mol). In addition, the morphologies of the fibers formed by the two dimers were characterized by transmission electron microscopy (TEM) and atomic force microscopy (AFM).
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Affiliation(s)
- Dongdong Wei
- School of Materials Science and Chemical Engineering, Anhui Jianzhu University, Hefei 230601, China
| | - Yongliang Qin
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China
| | - Zhipeng Xu
- School of Materials Science and Chemical Engineering, Anhui Jianzhu University, Hefei 230601, China
| | - Hui Liu
- School of Materials Science and Chemical Engineering, Anhui Jianzhu University, Hefei 230601, China
| | - Ranran Chen
- School of Materials Science and Chemical Engineering, Anhui Jianzhu University, Hefei 230601, China
| | - Yang Yu
- School of Advanced Manufacturing Engineering, Hefei University, Hefei 230601, China
| | - Di Wang
- School of Materials Science and Chemical Engineering, Anhui Jianzhu University, Hefei 230601, China
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3
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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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Zayakin I, Romanenko G, Bagryanskaya I, Ugrak B, Fedin M, Tretyakov E. Catalytic System for Cross-Coupling of Heteroaryl Iodides with a Nitronyl Nitroxide Gold Derivative at Room Temperature. Molecules 2023; 28:7661. [PMID: 38005383 PMCID: PMC10675334 DOI: 10.3390/molecules28227661] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 11/16/2023] [Accepted: 11/16/2023] [Indexed: 11/26/2023] Open
Abstract
A simple and highly effective methodology for the cross-coupling of heteroaryl iodides with NN-AuPPh3 at room temperature is reported. The protocol is based on a novel catalytic system consisting of Pd2(dba)3·CHCl3 and the phosphine ligand MeCgPPh having an adamantane-like framework. The present protocol was found to be well compatible with various heteroaryl iodides, thus opening new horizons in directed synthesis of functionalized nitronyl nitroxides and high-spin molecules.
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Affiliation(s)
- Igor Zayakin
- N. D. Zelinsky Institute of Organic Chemistry, Leninsky Ave. 47, Moscow 119991, Russia; (I.Z.); (B.U.)
| | - Galina Romanenko
- International Tomography Center, Institutskaya Str. 3a, Novosibirsk 630090, Russia;
| | - Irina Bagryanskaya
- N. N. Vorozhtsov Institute of Organic Chemistry, 9 Ac. Lavrentiev Avenue, Novosibirsk 630090, Russia;
| | - Bogdan Ugrak
- N. D. Zelinsky Institute of Organic Chemistry, Leninsky Ave. 47, Moscow 119991, Russia; (I.Z.); (B.U.)
| | - Matvey Fedin
- International Tomography Center, Institutskaya Str. 3a, Novosibirsk 630090, Russia;
| | - Evgeny Tretyakov
- N. D. Zelinsky Institute of Organic Chemistry, Leninsky Ave. 47, Moscow 119991, Russia; (I.Z.); (B.U.)
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5
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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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6
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Yue Z, Liu J, Baumgarten M, Wang D. Spirobifluorene Mediating the Spin-Spin Coupling of Nitronyl Nitroxide Diradicals. J Phys Chem A 2023; 127:1565-1575. [PMID: 36627248 DOI: 10.1021/acs.jpca.2c06648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
To investigate the mechanism of this spiro conjugation magnetic behavior, we designed and synthesized three diradicals─22'SBF-NN, 44'SBF-NN, and 27SBF-NN. They are bridged by spirobifluorene and nitronyl nitroxide (NN) diradicals as the spin centers. Notably, by SQUID and electron paramagnetic resonance (EPR) zero-field splitting data analyses, the 22'SBF-NN and 27SBF-NN diradicals exhibit intramolecular, distinctly antiferromagnetic (AF) coupling, with 2J(22'SBF-NN)/kB = -5.86 K and 2J(27SBF-NN)/kB = -24.6 K, respectively. The AF of 22'SBF-NN is opposite to that predicted by the spin density alternation rule based on Hund's rule. Diradical intramolecular conjugation coupling bridged by spiro-carbon conjugation is discussed, in which the 22'SBF-NN is smaller than that of 27SBF-NN, corresponding to the room-temperature EPR characterization. This spiro conjugation is weaker than the traditional planar conjugation and generally leads to a weaker spin-spin coupling in the helical biradical molecule. The EPR spectrum of the 44'SBF-NN diradical shows a deformed nine-line curve, indicating intramolecular exchange coupling. The density functional theory calculation gives a very weak coupling constant of 2Jcalc/kB = 0.06 K, with ferromagnetic (FM) interaction as the proof, which is consistent with the spin-polarized prediction. Further analysis of magnetic susceptibility χm and VT-EPR data shows that there is indeed an extremely weak FM interaction in the 44' position diradical. We find the bridge, which is a 44' substituted SBF structure, blocks the conjugation and contains a larger twist in steric hindrance, which also hampers sufficient spin density delocalization, resulting in a much weaker spin coupling interaction. Combined with the analysis of molecular orbital calculation results, the anomalous intramolecular AF coupling mechanism of 22'SBF-NN is further explained.
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Affiliation(s)
- Zheng Yue
- Anhui Key Laboratory of Advanced Building Materials, School of Materials Science and Chemical Engineering, Anhui Jianzhu University, Hefei 230601, China
| | - Jin Liu
- Anhui Key Laboratory of Advanced Building Materials, School of Materials Science and Chemical Engineering, Anhui Jianzhu University, Hefei 230601, China
| | - Martin Baumgarten
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Di Wang
- Anhui Key Laboratory of Advanced Building Materials, School of Materials Science and Chemical Engineering, Anhui Jianzhu University, Hefei 230601, China
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Teslenko FE, Fershtat LL. Unlocking Kuhn Verdazyls: New Synthetic Approach and Useful Mechanistic Insights. Int J Mol Sci 2023; 24:ijms24032693. [PMID: 36769015 PMCID: PMC9916651 DOI: 10.3390/ijms24032693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 01/20/2023] [Accepted: 01/20/2023] [Indexed: 02/04/2023] Open
Abstract
An optimized synthetic protocol toward the assembly of Kuhn verdazyls based on an azo coupling of arenediazonium salts with readily available hydrazones followed by the base-mediated cyclization of in situ formed formazans with formalin was developed. The scope and limitations of the presented method were revealed. Some new mechanistic insights on the formation of Kuhn verdazyls were also conducted. It was found that in contradiction with previously assumed hypotheses, the synthesis of verdazyls was accomplished via an intermediate formation of verdazylium cations which were in situ reduced to leucoverdazyls. The latter underwent deprotonation under basic conditions to generate corresponding anions which coproportionate with verdazylium cations to furnish the formation of Kuhn verdazyls. The spectroscopic and electrochemical behavior of the synthesized verdazyls was also studied. Overall, our results may serve as a reliable basis for further investigation in the chemistry and applications of verdazyls.
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Zayakin I, Tretyakov E, Akyeva A, Syroeshkin M, Burykina J, Dmitrenok A, Korlyukov A, Nasyrova D, Bagryanskaya I, Stass D, Ananikov V. Overclocking Nitronyl Nitroxide Gold Derivatives in Cross-Coupling Reactions. Chemistry 2023; 29:e202203118. [PMID: 36259387 DOI: 10.1002/chem.202203118] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Indexed: 12/12/2022]
Abstract
Nitronyl nitroxides are functional building blocks in cutting-edge research fields, such as the design of molecular magnets, the development of redox and photoswitchable molecular systems and the creation of redox-active components for organic and hybrid batteries. The key importance of the nitronyl nitroxide function is to translate molecular-level-optimized structures into nano-scale devices and new technologies. In spite of great importance, efficient and versatile synthetic approaches to these compounds still represent a challenge. Particularly, methods for the direct introduction of a nitronyl nitroxide moiety into aromatic systems possess many limitations. Here, we report gold derivatives of nitronyl nitroxide that can enter Pd(0)-catalysed cross-coupling reactions with various aryl bromides, affording the corresponding functionalized nitronyl nitroxides. Based on the high thermal stability and enhanced reactivity in catalytic transformation, a new reagent is suggested for the synthesis of radical systems via a universal cross-coupling approach.
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Affiliation(s)
- Igor Zayakin
- N. D. Zelinsky Institute of Organic Chemistry, 47 Leninsky Prosp., 119991, Moscow, Russia
| | - Evgeny Tretyakov
- N. D. Zelinsky Institute of Organic Chemistry, 47 Leninsky Prosp., 119991, Moscow, Russia
| | - Anna Akyeva
- N. D. Zelinsky Institute of Organic Chemistry, 47 Leninsky Prosp., 119991, Moscow, Russia
| | - Mikhail Syroeshkin
- N. D. Zelinsky Institute of Organic Chemistry, 47 Leninsky Prosp., 119991, Moscow, Russia
| | - Julia Burykina
- N. D. Zelinsky Institute of Organic Chemistry, 47 Leninsky Prosp., 119991, Moscow, Russia
| | - Andrey Dmitrenok
- N. D. Zelinsky Institute of Organic Chemistry, 47 Leninsky Prosp., 119991, Moscow, Russia
| | - Alexander Korlyukov
- A. N. Nesmeyanov Institute of Organoelement Compounds, 28 Vavilov Str., 119991, Moscow, Russia
| | - Darina Nasyrova
- N. D. Zelinsky Institute of Organic Chemistry, 47 Leninsky Prosp., 119991, Moscow, Russia
| | - Irina Bagryanskaya
- N. N. Vorozhtsov Novosibirsk Institute of Organic Chemistry, 9 Akad. Lavrentyev Prosp., 630090, Novosibirsk, Russia
| | - Dmitri Stass
- V. V. Voevodsky Institute of Chemical Kinetics and Combustion, 3 Institutskaya Str., 630090, Novosibirsk, Russia
| | - Valentine Ananikov
- N. D. Zelinsky Institute of Organic Chemistry, 47 Leninsky Prosp., 119991, Moscow, Russia
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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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Computational search for radical-bearing stilbene derivatives with switchable magnetic properties. Russ Chem Bull 2022. [DOI: 10.1007/s11172-022-3542-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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11
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Lipunova GN, Fedorchenko TG, Chupakhin ON. Verdazyls in Coordination Chemistry. RUSS J COORD CHEM+ 2022. [DOI: 10.1134/s1070328422070065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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12
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Zayakin IA, Korlyukov AA, Gorbunov DE, Gritsan NP, Akyeva AY, Syroeshkin MA, Stass DV, Tretyakov EV, Egorov MP. Au–Au Chemical Bonding in Nitronyl Nitroxide Gold(I) Derivatives. Organometallics 2022. [DOI: 10.1021/acs.organomet.2c00200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Igor A. Zayakin
- N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Avenue 47, Moscow 119991, Russian Federation
| | - Alexander A. Korlyukov
- A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilova Street 28, Moscow 119991, Russian Federation
| | - Dmitry E. Gorbunov
- V.V. Voevodsky Institute of Chemical Kinetics and Combustion, Siberian Branch of Russian Academy of Sciences, 3 Institutskaya Street, Novosibirsk 630090, Russian Federation
- A.V. Nikolaev Institute of Inorganic Chemistry, Siberian Branch of Russian Academy of Sciences, 3 Akad. Lavrentiev Avenue, Novosibirsk 630090, Russian Federation
| | - Nina P. Gritsan
- V.V. Voevodsky Institute of Chemical Kinetics and Combustion, Siberian Branch of Russian Academy of Sciences, 3 Institutskaya Street, Novosibirsk 630090, Russian Federation
| | - Anna Ya. Akyeva
- N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Avenue 47, Moscow 119991, Russian Federation
| | - Mikhail A. Syroeshkin
- N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Avenue 47, Moscow 119991, Russian Federation
| | - Dmitri V. Stass
- V.V. Voevodsky Institute of Chemical Kinetics and Combustion, Siberian Branch of Russian Academy of Sciences, 3 Institutskaya Street, Novosibirsk 630090, Russian Federation
| | - Evgeny V. Tretyakov
- N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Avenue 47, Moscow 119991, Russian Federation
| | - Mikhail P. Egorov
- N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Avenue 47, Moscow 119991, Russian Federation
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Starikov AG, Chegerev MG, Starikova AA, Minkin VI. Organic Polyradicals Based on Acenes. Computational Modeling. DOKLADY CHEMISTRY 2022. [DOI: 10.1134/s0012500822030028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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14
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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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15
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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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16
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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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17
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Li K, Feng Z, Ruan H, Sun Q, Zhao Y, Wang X. The catenation of a singlet diradical dication and modulation of diradical character by metal coordination. Chem Commun (Camb) 2022; 58:6457-6460. [DOI: 10.1039/d2cc01539k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A singlet bis(triarylamine) diradical dication and its zigzag 1D magnetic chain catenated by silver cations were isolated and characterized by single-crystal X-ray crystallography, EPR spectroscopy, SQUID measurements, cyclic voltammetry and...
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18
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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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19
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General Meeting of the Department of Chemistry and Materials Science of the Russian Academy of Sciences. Russ Chem Bull 2021. [DOI: 10.1007/s11172-021-3260-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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20
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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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21
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Gualandi L, Franchi P, Mezzina E, Goldup SM, Lucarini M. Spin-labelled mechanically interlocked molecules as models for the interpretation of biradical EPR spectra. Chem Sci 2021; 12:8385-8393. [PMID: 34221319 PMCID: PMC8221063 DOI: 10.1039/d1sc01462e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 05/14/2021] [Indexed: 12/20/2022] Open
Abstract
Biradical spin probes can provide detailed information about the distances between molecules/regions of molecules because the through-space coupling of radical centres, characterised by J, is strongly distance dependent. However, if the system can adopt multiple configurations, as is common in supramolecular complexes, the shape of the EPR spectrum is influenced not only by J but also the rate of exchange between different states. In practice, it is often hard to separate these variables and as a result, the effect of the latter is sometimes overlooked. To demonstrate this challenge unequivocally we synthesised rotaxane biradicals containing nitronyl nitroxide units at the termini of their axles. The rotaxanes exchange between the available biradical conformations more slowly than the corresponding non-interlocked axles but, despite this, in some cases, the EPR spectra of the axle and rotaxane remain remarkably similar. Detailed analysis allowed us to demonstrate that the similar EPR spectral shapes result from different combinations of J and rates of conformational interconversion, a phenomenon suggested theoretically more than 50 years ago. This work reinforces the idea that thorough analysis must be performed when interpreting the spectra of biradicals employed as spin probes in solution.
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Affiliation(s)
- Lorenzo Gualandi
- Department of Chemistry "Giacomo Ciamician", University of Bologna Via San Giacomo 11 Bologna Italy
| | - Paola Franchi
- Department of Chemistry "Giacomo Ciamician", University of Bologna Via San Giacomo 11 Bologna Italy
| | - Elisabetta Mezzina
- Department of Chemistry "Giacomo Ciamician", University of Bologna Via San Giacomo 11 Bologna Italy
| | - Stephen M Goldup
- Department of Chemistry, University of Southampton University Road, Highfield Southampton UK
| | - Marco Lucarini
- Department of Chemistry "Giacomo Ciamician", University of Bologna Via San Giacomo 11 Bologna Italy
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22
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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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