1
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Chang X, Arnold ME, Blinder R, Zolg J, Wischnat J, van Slageren J, Jelezko F, Kuehne AJC, von Delius M. A Stable Chichibabin Diradicaloid with Near-Infrared Emission. Angew Chem Int Ed Engl 2024; 63:e202404853. [PMID: 38695271 DOI: 10.1002/anie.202404853] [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: 03/11/2024] [Indexed: 06/21/2024]
Abstract
Conjugated molecules with multiple radical centers such as the iconic Chichibabin diradicaloid hold promise as building blocks in materials for quantum sensing and quantum information processing. However, it is a considerable challenge to design simple analogues of the Chichibabin hydrocarbon that are chemically inert, exhibit high diradical character and emit light at a distinct wavelength that may offer an optical readout of the spin state in functional ensembles. Here we describe the serendipitous discovery of the stable TTM-TTM diradicaloid, which exhibits high diradical character, a striking sky-blue color and near-infrared (NIR) emission (in solution). This combination of properties is unique among related diradicaloids and is due to the presence of hydrogen and chlorine atoms in "just the right positions", allowing a perfectly planar, yet predominantly benzenoid bridge to connect the two sterically stabilized radical centers. In-depth studies of the optical and magnetic properties suggest that this structural motif could become a mainstay building block of organic spin materials.
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Affiliation(s)
- Xingmao Chang
- Institute of Organic Chemistry, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Mona E Arnold
- Institute of Macromolecular and Organic Chemistry and Center for Integrated Quantum Science and Technology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Rémi Blinder
- Institute of Quantum Optics and Center for Integrated Quantum Science and Technology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Julia Zolg
- Institute of Macromolecular and Organic Chemistry and Center for Integrated Quantum Science and Technology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Jonathan Wischnat
- Institut für Physikalische Chemie and Center for Integrated Quantum Science and Technology, Universität Stuttgart, Pfaffenwaldring 55, 70569, Stuttgart, Germany
| | - Joris van Slageren
- Institut für Physikalische Chemie and Center for Integrated Quantum Science and Technology, Universität Stuttgart, Pfaffenwaldring 55, 70569, Stuttgart, Germany
| | - Fedor Jelezko
- Institute of Quantum Optics and Center for Integrated Quantum Science and Technology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Alexander J C Kuehne
- Institute of Macromolecular and Organic Chemistry and Center for Integrated Quantum Science and Technology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Max von Delius
- Institute of Organic Chemistry, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
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2
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Ishigaki Y, Mizuno SI, Sugawara K, Hashimoto T, Suzuki S, Suzuki T. Thermal Equilibrium Between Quinoid/Biradical Forms Enhancing Electrochemical Amphotericity. Chemistry 2024; 30:e202400916. [PMID: 38644537 DOI: 10.1002/chem.202400916] [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: 03/05/2024] [Revised: 04/08/2024] [Accepted: 04/21/2024] [Indexed: 04/23/2024]
Abstract
Upon dibenzo annulation on Thiele's hydrocarbon (tetraphenyl-p-quinodimethane), the quinoid form and the biradical form adopt quite different geometries, and thus are no longer resonance structures. When these two forms can interconvert rapidly due to the small energy barrier (ΔG≠), the equilibrated mixture contains both forms in a ratio that is determined by the energy difference (ΔGo) between the two forms. For a series of tetrakis[5-(4-methoxyphenyl)-2-thienyl]-substituted derivatives, the more stable quinoid form and the metastable biradical form coexist in solution as an equilibrated mixture due to small ΔG≠ (<15 kcal mol-1) and ΔGo (1-4 kcal mol-1), in which the proportion of the two forms can be regulated by temperature. Since the biradical form can undergo easy two-electron (2e) oxidation to the corresponding dications as well as easy 2e-reduction to the dianions, it exhibits very high electrochemical amphotericity. This character with a record-small span for not only the first oxidation and reduction potentials but also the second those, [E1 sum≈E2 sum=E2 ox-E2 red=ca. 1.4 V], is attained through thermally enhanced conversion to the biradical form from the corresponding quinoid form, the latter of which is less amphoteric due to higher Eox and lower Ered values.
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Affiliation(s)
- Yusuke Ishigaki
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, 060-0810, Japan
| | - Shin-Ichi Mizuno
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, 060-0810, Japan
| | - Kazuma Sugawara
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, 060-0810, Japan
| | - Takumi Hashimoto
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, 060-0810, Japan
| | - Shuichi Suzuki
- Graduate School of Engineering Science, Osaka University, Osaka, 560-8531, Japan
| | - Takanori Suzuki
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, 060-0810, Japan
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3
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Urgel JI, Sánchez-Grande A, Vicent DJ, Jelínek P, Martín N, Écija D. On-Surface Covalent Synthesis of Carbon Nanomaterials by Harnessing Carbon gem-Polyhalides. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024:e2402467. [PMID: 38864470 DOI: 10.1002/adma.202402467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2024] [Revised: 05/19/2024] [Indexed: 06/13/2024]
Abstract
The design of innovative carbon-based nanostructures stands at the forefront of both chemistry and materials science. In this context, π-conjugated compounds are of great interest due to their impact in a variety of fields, including optoelectronics, spintronics, energy storage, sensing and catalysis. Despite extensive research efforts, substantial knowledge gaps persist in the synthesis and characterization of new π-conjugated compounds with potential implications for science and technology. On-surface synthesis has emerged as a powerful discipline to overcome limitations associated with conventional solution chemistry methods, offering advanced tools to characterize the resulting nanomaterials. This review specifically highlights recent achievements in the utilization of molecular precursors incorporating carbon geminal (gem)-polyhalides as functional groups to guide the formation of π-conjugated 0D species, as well as 1D, quasi-1D π-conjugated polymers, and 2D nanoarchitectures. By delving into reaction pathways, novel structural designs, and the electronic, magnetic, and topological features of the resulting products, the review provides fundamental insights for a new generation of π-conjugated materials.
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Affiliation(s)
- José I Urgel
- IMDEA Nanoscience, Campus Universitario de Cantoblanco, Madrid, 28049, Spain
| | - Ana Sánchez-Grande
- Institute of Physics of the Czech Academy of Science, Praha, 16200, Czech Republic
| | - Diego J Vicent
- Departamento de Química Orgánica, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Madrid, 28040, Spain
| | - Pavel Jelínek
- Institute of Physics of the Czech Academy of Science, Praha, 16200, Czech Republic
| | - Nazario Martín
- IMDEA Nanoscience, Campus Universitario de Cantoblanco, Madrid, 28049, Spain
- Departamento de Química Orgánica, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Madrid, 28040, Spain
| | - David Écija
- IMDEA Nanoscience, Campus Universitario de Cantoblanco, Madrid, 28049, Spain
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4
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Mishra S, Vilas-Varela M, Lieske LA, Ortiz R, Fatayer S, Rončević I, Albrecht F, Frederiksen T, Peña D, Gross L. Bistability between π-diradical open-shell and closed-shell states in indeno[1,2-a]fluorene. Nat Chem 2024; 16:755-761. [PMID: 38332330 PMCID: PMC11087267 DOI: 10.1038/s41557-023-01431-7] [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: 03/08/2023] [Accepted: 12/19/2023] [Indexed: 02/10/2024]
Abstract
Indenofluorenes are non-benzenoid conjugated hydrocarbons that have received great interest owing to their unusual electronic structure and potential applications in nonlinear optics and photovoltaics. Here we report the generation of unsubstituted indeno[1,2-a]fluorene on various surfaces by the cleavage of two C-H bonds in 7,12-dihydroindeno[1,2-a]fluorene through voltage pulses applied by the tip of a combined scanning tunnelling microscope and atomic force microscope. On bilayer NaCl on Au(111), indeno[1,2-a]fluorene is in the neutral charge state, but it exhibits charge bistability between neutral and anionic states on the lower-workfunction surfaces of bilayer NaCl on Ag(111) and Cu(111). In the neutral state, indeno[1,2-a]fluorene exhibits one of two ground states: an open-shell π-diradical state, predicted to be a triplet by density functional and multireference many-body perturbation theory calculations, or a closed-shell state with a para-quinodimethane moiety in the as-indacene core. We observe switching between open- and closed-shell states of a single molecule by changing its adsorption site on NaCl.
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Affiliation(s)
| | - Manuel Vilas-Varela
- Center for Research in Biological Chemistry and Molecular Materials (CiQUS) and Department of Organic Chemistry, University of Santiago de Compostela, Santiago de Compostela, Spain
| | | | - Ricardo Ortiz
- Donostia International Physics Center (DIPC), Donostia-San Sebastián, Spain
| | - Shadi Fatayer
- Applied Physics Program, Physical Science and Engineering Division (PSE), King Abdullah University of Science and Technology (KAUST), Thuwal, Kingdom of Saudi Arabia
| | - Igor Rončević
- Department of Chemistry, University of Oxford, Oxford, UK
| | | | - Thomas Frederiksen
- Donostia International Physics Center (DIPC), Donostia-San Sebastián, Spain
- Ikerbasque, Basque Foundation for Science, Bilbao, Spain
| | - Diego Peña
- Center for Research in Biological Chemistry and Molecular Materials (CiQUS) and Department of Organic Chemistry, University of Santiago de Compostela, Santiago de Compostela, Spain.
| | - Leo Gross
- IBM Research Europe - Zurich, Rüschlikon, Switzerland.
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5
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Banachowicz P, Das M, Kruczała K, Siczek M, Sojka Z, Kijewska M, Pawlicki M. Breaking Global Diatropic Current to Tame Diradicaloid Character: Thiele's Hydrocarbon Under Macrocyclic Constraints. Angew Chem Int Ed Engl 2024; 63:e202400780. [PMID: 38407458 DOI: 10.1002/anie.202400780] [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: 01/11/2024] [Revised: 02/18/2024] [Accepted: 02/23/2024] [Indexed: 02/27/2024]
Abstract
A diradical/biradical character of organic derivatives is one of the key aspects of contemporary research focusing on the fundamental studies followed by potential applicability relying on the unique optical, electronic, or magnetic properties assigned to unpaired electrons. A precise involvement of two p-phenylenes into a cyclophane-like conjugated, diatropic system creates a flexible molecule with the two different characters of both subunits (benzene and quinone) imprinting into the structure a Kekulé delocalized system. A dynamic of both carbocyclic subunits, and their mutual interaction generates a singlet open-shell state (J=-1.25 kcal/mol) as documented spectroscopically (NMR and EPR). The extended theoretical analysis has proved a correlation between dihedral angle and the diradicaloid character that shifts from a closed-shell singlet to an open-shell state, eventually showing the y0=0.86 for 78 degrees and ΔEST=-0.34 kcal/mol.
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Affiliation(s)
- Piotr Banachowicz
- Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387, Kraków, Poland
| | - Mainak Das
- Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387, Kraków, Poland
| | - Krzysztof Kruczała
- Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387, Kraków, Poland
| | - Miłosz Siczek
- Department of Chemistry, University of Wrocław, F. Joliot-Curie 14, 50383, Wrocław, Poland
| | - Zbigniew Sojka
- Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387, Kraków, Poland
| | - Monika Kijewska
- Department of Chemistry, University of Wrocław, F. Joliot-Curie 14, 50383, Wrocław, Poland
| | - Miłosz Pawlicki
- Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387, Kraków, Poland
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6
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Zhou Z, Yang K, He L, Wang W, Lai W, Yang Y, Dong Y, Xie S, Yuan L, Zeng Z. Sulfone-Functionalized Chichibabin's Hydrocarbons: Stable Diradicaloids with Symmetry Breaking Charge Transfer Contributing to NIR Emission beyond 900 nm. J Am Chem Soc 2024; 146:6763-6772. [PMID: 38416700 DOI: 10.1021/jacs.3c13270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/01/2024]
Abstract
While monoradical emitters have emerged as a new route toward efficient organic light-emitting diodes, the luminescence property of organic diradicaloids is still scarcely explored. Herein, by devising a novel radical-radical coupling-based synthetic approach, we report a new class of sulfone-functionalized Chichibabin's hydrocarbon derivatives, SD-1-3, featuring varied substituent patterns and moderate to high diradical characters of 0.44-0.70, as highly stable diradicaloids with rarely seen NIR emission beyond 900 nm. Via comprehensive experimental and theoretical investigations, we reveal that the optoelectronic and magnetic properties of these materials are significantly tuned by the variations of substitutions (H/CF3/OMe) on the molecular skeletons. More importantly, quantum chemical computations indicate that the embedding of sulfone groups has contributed to a breaking of their quasi-C2 symmetry of these diradicaloid molecules and results in an excited-state charge transfer character. Therefore, a remarkably deep NIR emissive wavelength of up to 998 nm, together with a large Stokes shift (∼386 nm), is achieved for the CF3-based SD-2 molecule in tetrahydrofuran. To the best of our knowledge, such a luminescent wavelength of SD-2 has represented the longest wavelengths among the currently reported organic fluorescent radicals. Overall, our work not only establishes a new synthetic approach toward stable Chichibabin's hydrocarbons but also paves the way for designing NIR emissive open-shell materials with both fundamental understanding and feasible control of their luminescent properties.
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Affiliation(s)
- Zhibiao Zhou
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical EngineeringHunan University, Changsha 410082, China
- Shenzhen Research Institute of Hunan University,Nanshan District, Shenzhen 518000, China
- TCM and Ethnomedicine Innovation & Development International Laboratory, Innovative Materia Medica Research Institute, School of Pharmacy, Hunan University of Chinese Medicine, Changsha 410208, China
| | - Kun Yang
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical EngineeringHunan University, Changsha 410082, China
- Shenzhen Research Institute of Hunan University,Nanshan District, Shenzhen 518000, China
| | - Long He
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical EngineeringHunan University, Changsha 410082, China
- Key Laboratory of Theoretical Organic Chemistry and Functional Molecule of Ministry of Education, School of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan 411201, China
| | - Wei Wang
- TCM and Ethnomedicine Innovation & Development International Laboratory, Innovative Materia Medica Research Institute, School of Pharmacy, Hunan University of Chinese Medicine, Changsha 410208, China
| | - Weiming Lai
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical EngineeringHunan University, Changsha 410082, China
- Shenzhen Research Institute of Hunan University,Nanshan District, Shenzhen 518000, China
| | - Yinhua Yang
- Core Research Facilities, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Yueguo Dong
- Tianjin Jiuri New Material Co., Ltd., Tianjin 300384, China
| | - Sheng Xie
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical EngineeringHunan University, Changsha 410082, China
- Shenzhen Research Institute of Hunan University,Nanshan District, Shenzhen 518000, China
| | - Lin Yuan
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical EngineeringHunan University, Changsha 410082, China
- Shenzhen Research Institute of Hunan University,Nanshan District, Shenzhen 518000, China
| | - Zebing Zeng
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical EngineeringHunan University, Changsha 410082, China
- Shenzhen Research Institute of Hunan University,Nanshan District, Shenzhen 518000, China
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7
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Hu C, Kuhn L, Makurvet FD, Knorr ES, Lin X, Kawade RK, Mentink-Vigier F, Hanson K, Alabugin IV. Tethering Three Radical Cascades for Controlled Termination of Radical Alkyne peri-Annulations: Making Phenalenyl Ketones without Oxidants. J Am Chem Soc 2024; 146:4187-4211. [PMID: 38316011 DOI: 10.1021/jacs.3c13371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2024]
Abstract
Although Bu3Sn-mediated radical alkyne peri-annulations allow access to phenalenyl ring systems, the oxidative termination of these cascades provides only a limited selection of the possible isomeric phenalenone products with product selectivity controlled by the intrinsic properties of the new cyclic systems. In this work, we report an oxidant-free termination strategy that can overcome this limitation and enable selective access to the full set of isomerically functionalized phenalenones. The key to preferential termination is the preinstallation of a "weak link" that undergoes C-O fragmentation in the final cascade step. Breaking a C-O bond is assisted by entropy, gain of conjugation in the product, and release of stabilized radical fragments. This strategy is expanded to radical exo-dig cyclization cascades of oligoalkynes, which provide access to isomeric π-extended phenalenones. Conveniently, these cascades introduce functionalities (i.e., Bu3Sn and iodide moieties) amenable to further cross-coupling reactions. Consequently, a variety of polyaromatic diones, which could serve as phenalenyl-based open-shell precursors, can be synthesized.
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Affiliation(s)
- Chaowei Hu
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306-4390, United States
| | - Leah Kuhn
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306-4390, United States
| | - Favour D Makurvet
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306-4390, United States
| | - Erica S Knorr
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306-4390, United States
| | - Xinsong Lin
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306-4390, United States
| | - Rahul K Kawade
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306-4390, United States
| | - Frederic Mentink-Vigier
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, United States
| | - Kenneth Hanson
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306-4390, United States
| | - Igor V Alabugin
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306-4390, United States
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8
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Shen L, Gao X, Chang Z, Zhang C, Li Y, Lu J, Meng Q, Wu Q. Sufficient driving force for quinoidal isoindigo-based diradicaloids with tunable diradical characters. Phys Chem Chem Phys 2024; 26:2529-2538. [PMID: 38170813 DOI: 10.1039/d3cp05199d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Stable organic π-conjugated diradcialoids with tunable diradical characters can profoundly affect emerging technology. Over the past years, great efforts have been devoted to studying the structure-diradical character relationship in diradicaloids. Herein, a series of quinoidal isoindigo (IID) compounds with different attached terminal end groups were designed. Detailed analysis focuses on elucidating the driving force for evoking and enhancing the diradical character in the quinoidal IID systems. The arylene units of the IID core and the bridged aromatic units determine the contribution of the open-shell diradical form in the ground state. Diradical character y0 correlates well with bond length alternation (BLA), the total HOMA, and the total NICS(1)zz, and it is tuned by bridged aromatic units and terminal end groups in symmetric systems. The zwitterionic character weakens the diradical character in asymmetric systems to different extents. This work contributes to the deep understanding of evoking and enhancing the diradical character in quinoidal IID-based diradcialoids, providing useful guidelines to produce new molecules with desirable properties.
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Affiliation(s)
- Li Shen
- College of Chemical Engineering and Environmental Chemistry, Weifang University, Weifang, 261061, China.
| | - Xiaobo Gao
- College of Chemical Engineering and Environmental Chemistry, Weifang University, Weifang, 261061, China.
| | - Zhanqing Chang
- College of Chemical Engineering and Environmental Chemistry, Weifang University, Weifang, 261061, China.
| | - Changhao Zhang
- College of Chemical Engineering and Environmental Chemistry, Weifang University, Weifang, 261061, China.
| | - Yue Li
- College of Chemical Engineering and Environmental Chemistry, Weifang University, Weifang, 261061, China.
| | - Jitao Lu
- College of Chemical Engineering and Environmental Chemistry, Weifang University, Weifang, 261061, China.
| | - Qingguo Meng
- College of Chemical Engineering and Environmental Chemistry, Weifang University, Weifang, 261061, China.
| | - Qian Wu
- College of Chemical Engineering and Environmental Chemistry, Weifang University, Weifang, 261061, China.
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9
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Feng Z, Zhou J, He X, Wang B, Xie G, Qiao X, Liu L, Xie Z, Ma Y. Extremely Stable Perylene Bisimide-Bridged Regioisomeric Diradicals and Their Redox Properties. Chemistry 2024; 30:e202302943. [PMID: 37803935 DOI: 10.1002/chem.202302943] [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: 09/11/2023] [Revised: 10/05/2023] [Accepted: 10/06/2023] [Indexed: 10/08/2023]
Abstract
Excellent stability is an essential premise for organic diradicals to be used in organic electronic and spintronic devices. We have attached two tris(2,4,6-trichlorophenyl)methyl (TTM) radical building blocks to the two sides of perylene bisimide (PBI) bridges and obtained two regioisomeric diradicals (1,6-TTM-PBI and 1,7-TTM-PBI). Both of the isomers show super stability rather than the monomeric TTM under ambient conditions, due to the increased conjugation and the electron-withdrawing effects of the PBI bridges. The diradicals show distinct and reversible multistep redox processes, and a spectro-electrochemistry investigation revealed the generation of organic mixed-valence (MV) species during reduction processes. The two diradicals have singlet ground states, very small singlet-triplet energy gaps (ΔES-T ) and a pure open-shell character (with diradical character y0 =0.966 for 1,6-TTM-PBI and 0.967 for 1,7-TTM-PBI). This work opens a window to developing very stable diradicals and offers the opportunity of their further application in optical, electronic and magnetic devices.
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Affiliation(s)
- Zhibin Feng
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou, 510640, P. R. China
| | - Jiadong Zhou
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou, 510640, P. R. China
| | - Xiandong He
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou, 510640, P. R. China
| | - Bohan Wang
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou, 510640, P. R. China
| | - Guojing Xie
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou, 510640, P. R. China
| | - Xianfeng Qiao
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou, 510640, P. R. China
| | - Linlin Liu
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou, 510640, P. R. China
| | - Zengqi Xie
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou, 510640, P. R. China
| | - Yuguang Ma
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou, 510640, P. R. China
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10
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Vasiļevska A, Slanina T. Structure-property-function relationships of stabilized and persistent C- and N-based triaryl radicals. Chem Commun (Camb) 2024; 60:252-264. [PMID: 38086625 DOI: 10.1039/d3cc05706b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2024]
Abstract
Structurally similar C- and N-based triaryl radicals are among the most commonly used structural motifs in stable, open-shell, organic molecules. The application of such species is associated with their stability, properties and structural design. This study summarizes the basic stabilization and persistence principles of C- and N-based triaryl radicals and highlights recent advances in design strategies of radicals tailored for specific applications.
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Affiliation(s)
- Anna Vasiļevska
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, 166 10 Prague 6, Czech Republic.
- Department of Organic Chemistry, Charles University, 128 00 Prague 2, Czech Republic
| | - Tomáš Slanina
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, 166 10 Prague 6, Czech Republic.
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11
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Yan M, Hou L, Deng X, Shi X, Jiang F, Wang M. Anthraquinodimethane-Based Molecular Switches Tethered by Four-Arm Star-like Polymers. Chemistry 2023:e202303740. [PMID: 38149886 DOI: 10.1002/chem.202303740] [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: 11/09/2023] [Revised: 12/21/2023] [Accepted: 12/22/2023] [Indexed: 12/28/2023]
Abstract
Molecular switches that reversibly change their structures and physical properties are important for applications such as sensing and information processing at molecular scales. In order to avoid the intermolecular aggregation that is often detrimental to the stimuli-responses of molecular switches, previous studies of molecular switches have been often conducted in dilute solutions which are difficult for applications in solid-state devices. Here we report molecular design and synthesis that integrates anthraquinodimethane as molecular switching units into polymers with amenable processibility in solid states. Optical and electron spin resonance characterizations indicate that the four-arm polymers of poly(ϵ-caprolactone) or poly(D,L-lactide) tethered from anthraquinodimethane slow down the dynamics of the conformational switching between the folded and the twisted conformations, enhance the photoluminescence in solid states and impart materials with a small energy gap from singlet ground state to thermally accessible triplet state.
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Affiliation(s)
- Mengwen Yan
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, 518172, China
| | - Liman Hou
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, 518172, China
| | - Xianjun Deng
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, 518172, China
| | - Xinyuan Shi
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, 518172, China
| | - Feng Jiang
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, 518172, China
| | - Mingfeng Wang
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, 518172, China
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12
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Ishigaki Y, Harimoto T, Shimajiri T, Suzuki T. Carbon-based Biradicals: Structural and Magnetic Switching. Chem Rev 2023; 123:13952-13965. [PMID: 37948658 DOI: 10.1021/acs.chemrev.3c00376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2023]
Abstract
Sterically hindered C═C double bonds often deform into a bent or twisted geometry. Thus, many overcrowded ethylenes or anthraquinodimethanes can adopt multiple conformations, such as a folded form or a twisted form, which are interconvertible under the application of external stimuli. A perpendicular form with biradical character can also be adopted when designed to incorporate a stable carbon-based radical unit, which is involved in stimuli-responsive magnetic switching accompanied by a structural change. This review focuses on recent advances in the development of such strained π-electron systems and reveals the factors that affect the mutual interconversion and switching behavior. The energy barrier for the interconversion of conformational isomers is affected by the tricyclic skeleton or bulky substituents on the C═C double bonds, whereas the relative stability of the perpendicular biradical form increases with the additional insertion of 9,10-anthrylene units into the C═C double bonds.
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Affiliation(s)
- Yusuke Ishigaki
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Takashi Harimoto
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Takuya Shimajiri
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan
- Creative Research Institution, Hokkaido University, Sapporo 001-0021, Japan
| | - Takanori Suzuki
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan
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13
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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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14
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Gu Q, Lu X, Chen C, Hu R, Wang X, Sun G, Kang F, Yang J, Wang X, Wu J, Li YY, Peng YK, Qin W, Han Y, Liu X, Zhang Q. Thermally Induced Persistent Covalent-Organic Frameworks Radicals. ACS NANO 2023. [PMID: 38014811 DOI: 10.1021/acsnano.3c08313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
Persistent covalent-organic framework (COF) radicals hold important applications in magnetics and spintronics; however, their facile synthesis remains a daunting challenge. Here, three p-phenylenediacetonitrile-based COFs (named CityU-4, CityU-5, and CityU-6) were synthesized. Upon heat treatment (250 °C for CityU-4 and CityU-5 or 220 °C for CityU-6), these frameworks were brought into their persistent radical forms (no obvious changes after at least one year), together with several observable factors, including color changes, red-shifted absorption, the appearance of electron spin resonance (ESR) signals, and detectable magnetic susceptibility. The theoretical simulation suggests that after heat treatment, lower total energy and nonzero spin density are two main factors to guarantee persistent COFs radicals and polarized spin distributions. This work provides an efficient method for the preparation of persistent COF radicals with promising potentials.
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Affiliation(s)
- Qianfeng Gu
- Department of Materials Science and Engineering, City University of Hong Kong, Tat Chee Avenue 83, Kowloon, Hong Kong SAR 999077, P. R. China
| | - Xiangqian Lu
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, P. R. China
| | - Cailing Chen
- Advanced Membranes and Porous Materials (AMPM) Center, Physical Science and Engineering Division, King Ab-dullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Renjie Hu
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, P. R. China
| | - Xin Wang
- Department of Materials Science and Engineering, City University of Hong Kong, Tat Chee Avenue 83, Kowloon, Hong Kong SAR 999077, P. R. China
| | - Guohan Sun
- Department of Chemistry, City University of Hong Kong, Tat Chee Avenue 83, Kowloon, Hong Kong SAR 999077, P. R. China
| | - Fangyuan Kang
- Department of Materials Science and Engineering, City University of Hong Kong, Tat Chee Avenue 83, Kowloon, Hong Kong SAR 999077, P. R. China
| | - Jinglun Yang
- Department of Materials Science and Engineering, City University of Hong Kong, Tat Chee Avenue 83, Kowloon, Hong Kong SAR 999077, P. R. China
| | - Xiang Wang
- Department of Materials Science and Engineering, City University of Hong Kong, Tat Chee Avenue 83, Kowloon, Hong Kong SAR 999077, P. R. China
| | - Jinghang Wu
- Department of Materials Science and Engineering, City University of Hong Kong, Tat Chee Avenue 83, Kowloon, Hong Kong SAR 999077, P. R. China
| | - Yang Yang Li
- Department of Materials Science and Engineering, City University of Hong Kong, Tat Chee Avenue 83, Kowloon, Hong Kong SAR 999077, P. R. China
| | - Yung-Kang Peng
- Department of Chemistry, City University of Hong Kong, Tat Chee Avenue 83, Kowloon, Hong Kong SAR 999077, P. R. China
| | - Wei Qin
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, P. R. China
| | - Yu Han
- Advanced Membranes and Porous Materials (AMPM) Center, Physical Science and Engineering Division, King Ab-dullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Xiaogang Liu
- Department of Chemistry and the N.1 Institute for Health, National University of Singapore, Singapore 117543, Singapore
| | - Qichun Zhang
- Department of Materials Science and Engineering, City University of Hong Kong, Tat Chee Avenue 83, Kowloon, Hong Kong SAR 999077, P. R. China
- Department of Chemistry & Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, Tat Chee Avenue 83, Kowloon, Hong Kong SAR 999077, P. R. China
- Department of Chemistry, City University of Hong Kong, Tat Chee Avenue 83, Kowloon, Hong Kong SAR 999077, P. R. China
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15
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Usui K, Amano A, Murayama K, Sasaya M, Kusumoto R, Umeno T, Murase S, Iizuka N, Matsumoto S, Fuchi Y, Takahashi K, Kawahata M, Kobori Y, Karasawa S. Photoisomerization of "Partially Embedded Dihydropyridazine" with a Helical Structure. Chemistry 2023; 29:e202302413. [PMID: 37612241 DOI: 10.1002/chem.202302413] [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: 07/26/2023] [Revised: 08/21/2023] [Accepted: 08/23/2023] [Indexed: 08/25/2023]
Abstract
Herein, we report the synthesis of two "partially embedded fused-dihydropyridazine N-aryl aza[5]helicene derivatives" (PDHs) and the demonstration of their intrinsic photo-triggered multi-functional properties based on a Kekulé biradical structure. Introducing bulky electron-withdrawing trifluoromethyl or pentafluoroethyl groups into the aza[5]helicene framework (PDH-CF3 and -C2 F5 ) gives PDH axial chirality based on the helicity of the P and M forms, even at room temperature. Upon photo-irradiation of PDH-CF3 in a frozen solution, an ESR signal from the triplet biradical with zero-field splitting values, generated by N-N bond dissociation, was observed. However, when the irradiation was turned off, the ESR signal became silent, thus indicating the existence of two equilibria: between the biradical and quinoidal forms based on the Kekulé structure, and between N-N bond cleavage and recombination. The observed photo- and thermally induced behaviors indicate that T-type photochromic molecules are involved in the photoisomerization mechanism involving the two equilibria. Inspired by the photoisomerization, chirality control of PDH by photoracemization was achieved. Multiple functionalities, such as T-type photochromism, photo-excitation-mediated triplet biradical formation, and photoracemization, which are attributed to the "partially embedded dihydropyridazine" structure, are demonstrated.
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Affiliation(s)
- Kazuteru Usui
- Faculty of Pharmaceutical Sciences, Showa Pharmaceutical University, 3512-1 Higashi-tamagawagakuen, Machida, Tokyo, 194-8543, Japan
| | - Ami Amano
- Faculty of Pharmaceutical Sciences, Showa Pharmaceutical University, 3512-1 Higashi-tamagawagakuen, Machida, Tokyo, 194-8543, Japan
| | - Kasumi Murayama
- Department of Chemistry, Graduate School of Science Kobe University, Kobe, Hyogo, 657-8501, Japan
| | - Miho Sasaya
- Faculty of Pharmaceutical Sciences, Showa Pharmaceutical University, 3512-1 Higashi-tamagawagakuen, Machida, Tokyo, 194-8543, Japan
| | - Ryota Kusumoto
- Department of Chemistry, Graduate School of Science Kobe University, Kobe, Hyogo, 657-8501, Japan
| | - Tomohiro Umeno
- Faculty of Pharmaceutical Sciences, Showa Pharmaceutical University, 3512-1 Higashi-tamagawagakuen, Machida, Tokyo, 194-8543, Japan
| | - Satsuki Murase
- Faculty of Pharmaceutical Sciences, Showa Pharmaceutical University, 3512-1 Higashi-tamagawagakuen, Machida, Tokyo, 194-8543, Japan
| | - Naoko Iizuka
- Faculty of Pharmaceutical Sciences, Showa Pharmaceutical University, 3512-1 Higashi-tamagawagakuen, Machida, Tokyo, 194-8543, Japan
| | - Shota Matsumoto
- Faculty of Pharmaceutical Sciences, Showa Pharmaceutical University, 3512-1 Higashi-tamagawagakuen, Machida, Tokyo, 194-8543, Japan
| | - Yasufumi Fuchi
- Faculty of Pharmaceutical Sciences, Showa Pharmaceutical University, 3512-1 Higashi-tamagawagakuen, Machida, Tokyo, 194-8543, Japan
| | - Kazuyuki Takahashi
- Department of Chemistry, Graduate School of Science Kobe University, Kobe, Hyogo, 657-8501, Japan
| | - Masatoshi Kawahata
- Faculty of Pharmaceutical Sciences, Showa Pharmaceutical University, 3512-1 Higashi-tamagawagakuen, Machida, Tokyo, 194-8543, Japan
| | - Yasuhiro Kobori
- Department of Chemistry, Graduate School of Science Kobe University, Kobe, Hyogo, 657-8501, Japan
- Molecular Photoscience Research Center, Graduate School of Science Kobe University, Kobe, Hyogo, 657-8501, Japan
| | - Satoru Karasawa
- Faculty of Pharmaceutical Sciences, Showa Pharmaceutical University, 3512-1 Higashi-tamagawagakuen, Machida, Tokyo, 194-8543, Japan
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16
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Miller PD, Shultz DA, Mengell J, Kirk ML, Wojtas L. Variation from closed-shell to open shell electronic structures in oligothiophene bis(dioxolene) complexes. Chem Sci 2023; 14:12264-12276. [PMID: 37969598 PMCID: PMC10631215 DOI: 10.1039/d3sc02341a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Accepted: 10/07/2023] [Indexed: 11/17/2023] Open
Abstract
A series of oligothiophene bis(dioxolene) complexes, SQ-Thn-SQ (SQ = S = ½TpCum,MeZnII(3-tert-butyl-orthosemiquinonate); TpCum,Me = tris(5-cumenyl-3-methylpyrazolyl)borate anion) have been synthesized, structurally characterized, and studied as a function of the number of thiophene bridging units, n (n = 0-3) using a combination of variable-temperature (VT) electronic absorption and EPR spectroscopies, and VT magnetic susceptibility measurements. The thiophene bridge bond lengths determined by X-ray crystallography display dramatic differences across the SQ-Thn-SQ series. Bridge bond deviation values (Σ|Δi|) display a progressive change in the nature of the bridge fragment bonding as the number of thiophene groups increases, with quinoidal bridge character for n = 1 (SQ-Th-SQ) and biradical character with "aromatic" bridge bond lengths for n = 3 (SQ-Th3-SQ). Remarkably, for n = 2 (SQ-Th2-SQ) the nature of the bridge fragment is intermediate between quinoid and biradical aromatic, which we describe as having open-shell character as opposed to biradicaloid since the open-shell biradical configuration does not have the correct symmetry to mix with the quinoidal ground-state configuration. This bridge bonding character is reflected in the energies of the lowest lying open-shell states for these three molecules. The SQ-Th-SQ molecule is diamagnetic at all temperatures studied, and we provide evidence for SQ-SQ antiferromagnetic exchange coupling and population of triplet states in SQ-Th2-SQ and SQ-Th3-SQ, with JSQ-SQ(ave) = -279 cm-1 (VT EPR/electronic absorption/magnetic susceptibility) and JSQ-SQ = -117 cm-1 (VT EPR/electronic absorption/magnetic susceptibility), respectively. The results have been interpreted in the context of state configurational mixing within a simplified 4-electron, 3-orbital model that explicitly contains contributions of a bridge fragment. Variable-temperature spectroscopic- and magnetic susceptibility data are consistent with two low-lying open-shell states for SQ-Th3-SQ, but three low-lying states (one closed-shell and two open-shell) for SQ-Th2-SQ. This model provides a simple symmetry-based framework to understand the continuum of electronic and geometric structures of this class of molecules as a function of the number of thiophene units in the bridge.
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Affiliation(s)
- Paul D Miller
- Department of Chemistry, North Carolina State University Raleigh North Carolina 27695-8204 USA
| | - David A Shultz
- Department of Chemistry, North Carolina State University Raleigh North Carolina 27695-8204 USA
| | - Joshua Mengell
- Department of Chemistry and Chemical Biology, The University of New Mexico MSC03 2060, 1 University of New Mexico Albuquerque NM 87131-0001 USA
| | - Martin L Kirk
- Department of Chemistry and Chemical Biology, The University of New Mexico MSC03 2060, 1 University of New Mexico Albuquerque NM 87131-0001 USA
- The Center for High Technology Materials, The University of New Mexico Albuquerque New Mexico 87106 USA
- Center for Quantum Information and Control (CQuIC), The University of New Mexico Albuquerque New Mexico 87131-0001 USA
| | - Lukasz Wojtas
- Department of Chemistry, University of South Florida 4202 E. Fowler Avenue, CHE 205 Tampa FL 33620-5250 USA
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17
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Tobe Y. An open-shell molecule that exhibits conformational dynamics. Nat Chem 2023; 15:1490-1492. [PMID: 37907606 DOI: 10.1038/s41557-023-01350-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2023]
Affiliation(s)
- Yoshito Tobe
- Department of Applied Chemistry, National Yang Ming Chiao Tung University, Hsinchu, Taiwan.
- Nanoscience and Nanotechnology Center, The Institute of Scientific and Industrial Research (SANKEN), Osaka University, Ibaraki, Japan.
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18
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Vicent DJ, Pérez-Escribano M, Cárdenas-Valdivia A, Barragán A, Calbo J, Urgel JI, Écija D, Santos J, Casado J, Ortí E, Martín N. Dimeric tetrabromo- p-quinodimethanes: synthesis and structural/electronic properties. Chem Sci 2023; 14:10112-10120. [PMID: 37772123 PMCID: PMC10530488 DOI: 10.1039/d3sc01615c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Accepted: 08/09/2023] [Indexed: 09/30/2023] Open
Abstract
Despite their great potential as molecular building blocks for organic synthesis, tetrabromo-p-quinodimethanes (TBQs) are a relatively unknown family of compounds. Herein, we showcase a series of five derivatives incorporating two tetrabromo-anthraquinodimethane (TBAQ) units linked by π-conjugated spacers of different nature and length. The resulting dimers TBQ1-5 are fully characterised by means of thorough spectroscopic measurements and theoretical calculations. Interestingly, owing to the steric hindrance imposed by the four bulky bromine atoms, the TBAQ fragments adopt a characteristically warped geometry, somehow resemblant of a butterfly, and the novel dimers show a complex NMR pattern with signal splittings. To ascertain whether dynamic processes regarding fluxional inversion of the butterfly configurations are involved, first-principles calculations assessing the interconversion energy barriers are performed. Three possible stereoisomers are predicted involving two diastereomers, thus accounting for the observed NMR spectra. The rotational freedom of the TBAQ units around the π-conjugated linker influences the structural and electronic properties of TBQ1-5 and modulates the electronic communication between the terminal TBAQ moieties. The role of the linker on the electronic properties is investigated by Raman and UV-vis spectroscopies, theoretical calculations and UV-vis measurements at low temperature. TBQ1-5 are of interest as less-explored structural building precursors for a variety of scientific areas. Finally, the sublimation, self-assembly and reactivity on Au(111) of TBQ3 is assessed.
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Affiliation(s)
- Diego J Vicent
- Departamento de Química Orgánica, Facultad de Ciencias Químicas, Universidad Complutense de Madrid 28040 Madrid Spain
| | | | | | - Ana Barragán
- IMDEA-Nanociencia C/ Faraday, 9, Campus de Cantoblanco 28049 Madrid Spain
| | - Joaquín Calbo
- Instituto de Ciencia Molecular, Universidad de Valencia 46980 Paterna Spain
| | - José I Urgel
- IMDEA-Nanociencia C/ Faraday, 9, Campus de Cantoblanco 28049 Madrid Spain
| | - David Écija
- IMDEA-Nanociencia C/ Faraday, 9, Campus de Cantoblanco 28049 Madrid Spain
| | - José Santos
- Departamento de Química Orgánica, Facultad de Ciencias Químicas, Universidad Complutense de Madrid 28040 Madrid Spain
| | - Juan Casado
- Departamento de Química Física, Universidad de Málaga 229071 Malaga Spain
| | - Enrique Ortí
- Instituto de Ciencia Molecular, Universidad de Valencia 46980 Paterna Spain
| | - Nazario Martín
- Departamento de Química Orgánica, Facultad de Ciencias Químicas, Universidad Complutense de Madrid 28040 Madrid Spain
- IMDEA-Nanociencia C/ Faraday, 9, Campus de Cantoblanco 28049 Madrid Spain
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19
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Kang HW, Liu YC, Shao WK, Wei YC, Hsieh CT, Chen BH, Lu CH, Yang SD, Cheng MJ, Chou PT, Chiang MH, Wu YT. Synthesis, structural analysis, and properties of highly twisted alkenes 13,13'-bis(dibenzo[a,i]fluorenylidene) and its derivatives. Nat Commun 2023; 14:5248. [PMID: 37640729 PMCID: PMC10462764 DOI: 10.1038/s41467-023-40990-8] [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: 06/07/2023] [Accepted: 08/18/2023] [Indexed: 08/31/2023] Open
Abstract
The rotation of a C = C bond in an alkene can be efficiently accelerated by creating the high-strain ground state and stabilizing the transition state of the process. Herein, the synthesis, structures, and properties of several highly twisted alkenes are comprehensively explored. A facile and practical synthetic approach to target molecules is developed. The twist angles and lengths of the central C = C bonds in these molecules are 36-58° and 1.40-1.43 Å, respectively, and confirmed by X-ray crystallography and DFT calculations. A quasi-planar molecular half with the π-extended substituents delivers a shallow rotational barrier (down to 2.35 kcal/mol), indicating that the rotation of the C = C bond is as facile as that of the aryl-aryl bond in 2-flourobiphenyl. Other versatile and unique properties of the studied compounds include a broad photoabsorption range (from 250 up to 1100 nm), a reduced HOMO-LUMO gap (1.26-1.68 eV), and a small singlet-triplet energy gap (3.65-5.68 kcal/mol).
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Affiliation(s)
- Hao-Wen Kang
- Department of Chemistry, National Cheng Kung University, 70101, Tainan, Taiwan
| | - Yu-Chiao Liu
- Institute of Chemistry, Academia Sinica, 11529, Taipei, Taiwan
| | - Wei-Kai Shao
- Department of Chemistry, National Cheng Kung University, 70101, Tainan, Taiwan
| | - Yu-Chen Wei
- Department of Chemistry, National Taiwan University, 10617, Taipei, Taiwan
| | - Chi-Tien Hsieh
- Department of Chemistry, National Cheng Kung University, 70101, Tainan, Taiwan
| | - Bo-Han Chen
- Department of Electrical Engineering, National Tsing Hua University, 30013, Hsinchu, Taiwan
| | - Chih-Hsuan Lu
- Department of Electrical Engineering, National Tsing Hua University, 30013, Hsinchu, Taiwan
| | - Shang-Da Yang
- Department of Electrical Engineering, National Tsing Hua University, 30013, Hsinchu, Taiwan
| | - Mu-Jeng Cheng
- Department of Chemistry, National Cheng Kung University, 70101, Tainan, Taiwan
| | - Pi-Tai Chou
- Department of Chemistry, National Taiwan University, 10617, Taipei, Taiwan.
| | - Ming-Hsi Chiang
- Institute of Chemistry, Academia Sinica, 11529, Taipei, Taiwan.
- Department of Medical and Applied Chemistry, Kaohsiung Medical University, 80708, Kaohsiung, Taiwan.
| | - Yao-Ting Wu
- Department of Chemistry, National Cheng Kung University, 70101, Tainan, Taiwan.
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20
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Li L, Prindle CR, Shi W, Nuckolls C, Venkataraman L. Radical Single-Molecule Junctions. J Am Chem Soc 2023; 145:18182-18204. [PMID: 37555594 DOI: 10.1021/jacs.3c04487] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/10/2023]
Abstract
Radicals are unique molecular systems for applications in electronic devices due to their open-shell electronic structures. Radicals can function as good electrical conductors and switches in molecular circuits while also holding great promise in the field of molecular spintronics. However, it is both challenging to create stable, persistent radicals and to understand their properties in molecular junctions. The goal of this Perspective is to address this dual challenge by providing design principles for the synthesis of stable radicals relevant to molecular junctions, as well as offering current insight into the electronic properties of radicals in single-molecule devices. By exploring both the chemical and physical properties of established radical systems, we will facilitate increased exploration and development of radical-based molecular systems.
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Affiliation(s)
- Liang Li
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Claudia R Prindle
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Wanzhuo Shi
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Colin Nuckolls
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Latha Venkataraman
- Department of Chemistry, Columbia University, New York, New York 10027, United States
- Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027, United States
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21
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Anglada JM, Poater J, Moreira IDPR, Bofill JM. Controlling the Diradical Character of Thiele Like Compounds. J Org Chem 2023. [PMID: 37339010 DOI: 10.1021/acs.joc.3c00482] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/22/2023]
Abstract
Organic diradicals play an important role in many fields of chemistry, biochemistry, and materials science. In this work, by means of high-level theoretical calculations, we have investigated the effect of representative chemical substituents in p-quinodimethane (pQDM) and Thiele's hydrocarbons with respect to the singlet-triplet energy gap, a feature characterizing their diradical character. We show how the nature of the substituents has a very important effect in controlling the singlet-triplet energy gap so that several compounds show diradical features in their ground electronic state. Importantly, steric effects appear to play the most determinant role for pQDM analogues, with minor effects of the substituents in the central ring. For Thiele like compounds, we found that electron-withdrawing groups in the central ring favor the quinoidal form with a low or almost null diradical character, whereas electron-donating group substituents favor the aromatic-diradical form if the electron donation does not exceed 6-π electrons. In this case, if there is an excess of electron donation, the diradical character is reduced. The electronic spectrum of these compounds is also calculated, and we predict that the most intense bands occur in the visible region, although in some cases characteristic electronic transition in the near-IR region may appear.
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Affiliation(s)
- Josep M Anglada
- Departament de Química Biològica (IQAC-CSIC), Carrer Jordi Girona, 18, 08034 Barcelona, Spain
| | - Jordi Poater
- Departament de Química Inorgànica i Orgànica & IQTCUB, Universitat de Barcelona, Martí i Franquès 1-11, 08028 Barcelona, Spain
- ICREA, Pg. Lluís Companys 23, 08010 Barcelona, Spain
| | - Ibério de P R Moreira
- Departament de Ciència de Materials i Química Física, Secció de Química Física, Universitat de Barcelona, 08028 Barcelona, Spain
- IQTCUB, Universitat de Barcelona, Martí i Franquès, 1-11, 08028 Barcelona, Spain
| | - Josep Maria Bofill
- Departament de Química Inorgànica i Orgànica & IQTCUB, Universitat de Barcelona, Martí i Franquès 1-11, 08028 Barcelona, Spain
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22
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Yang X, Hou S, Su M, Zhan Q, Zhang H, Quintero SM, Liu X, Liu J, Hong W, Casado J, Wu Q, Lambert CJ, Zheng Y. Quasi-Free Electron States Responsible for Single-Molecule Conductance Enhancement in Stable Radical. J Phys Chem Lett 2023; 14:4004-4010. [PMID: 37083476 DOI: 10.1021/acs.jpclett.3c00536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Stable organic radicals, which possess half-filled orbitals in the vicinity of the Fermi energy, are promising candidates for electronic devices. In this Letter, using a combination of scanning-tunneling-microscopy-based break junction (STM-BJ) experiments and quantum transport theory, a stable fluorene-based radical is investigated. We demonstrate that the transport properties of a series of fluorene derivatives can be tuned by controlling the degree of localization of certain orbitals. More specifically, radical 36-FR has a delocalized half-filled orbital resulting in Breit-Wigner resonances, leading to an unprecedented conductance enhancement of 2 orders of magnitude larger than the neutral nonradical counterpart (36-FOH). In other words, conversion from a closed-shell fluorene derivative to the free radical in 36-FR opens an electron transport path which massively enhances the conductance. This new understanding of the role of radicals in single-molecule junctions opens up a novel design strategy for single-molecule-based spintronic devices.
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Affiliation(s)
- Xingzhou Yang
- Department of Pharmacy, Sichuan Provincial People's Hospital, School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 610072, People's Republic of China
| | - Songjun Hou
- Department of Physics, Lancaster University, Lancaster LA1 4YB, U.K
| | - Meiling Su
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xia-men University, Xiamen 361005, People's Republic of China
| | - Qian Zhan
- Department of Pharmacy, Sichuan Provincial People's Hospital, School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 610072, People's Republic of China
| | - Hanjun Zhang
- Department of Pharmacy, Sichuan Provincial People's Hospital, School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 610072, People's Republic of China
| | - Sergio M Quintero
- Department of Physical Chemistry, University of Málaga, Andalucia-Tech Campus de Teatinos s/n, Málaga 29071, Spain
| | - Xiaodong Liu
- Department of Pharmacy, Sichuan Provincial People's Hospital, School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 610072, People's Republic of China
| | - Junyang Liu
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xia-men University, Xiamen 361005, People's Republic of China
| | - Wenjing Hong
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xia-men University, Xiamen 361005, People's Republic of China
| | - Juan Casado
- Department of Physical Chemistry, University of Málaga, Andalucia-Tech Campus de Teatinos s/n, Málaga 29071, Spain
| | - Qingqing Wu
- Department of Physics, Lancaster University, Lancaster LA1 4YB, U.K
| | - Colin J Lambert
- Department of Physics, Lancaster University, Lancaster LA1 4YB, U.K
| | - Yonghao Zheng
- Department of Pharmacy, Sichuan Provincial People's Hospital, School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 610072, People's Republic of China
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23
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Wang P, Hu J, Xu Z, Pu Z, Sato S, Zhang X, Hu W, Sun Z. Synthesis and structure elucidation of triarylmethyl radicals with anthryl substitution. Chem Commun (Camb) 2023; 59:2015-2018. [PMID: 36723079 DOI: 10.1039/d2cc06083c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Two stable triarylmethyl radicals with one or two anthryl substitutions are synthesized in gram scale, and are isolated in the crystalline state. Detailed structural elucidation with X-ray crystallographic analysis and DFT calculations revealed that the twisted structure is more energetically favorable than the folded structure, and consequently, the spin density is mainly localized at the methyl carbon. The spin distribution leads to unique physical properties, making them promising open-shell organic materials.
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Affiliation(s)
- Peng Wang
- Institute of Molecular Plus, Department of Chemistry, Tianjin University, 92 Weijin Road, Tianjin, 300072, China. .,Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Department of Chemistry, School of Science, Tianjin University, Tianjin 300072, China.
| | - Jinlian Hu
- Institute of Molecular Plus, Department of Chemistry, Tianjin University, 92 Weijin Road, Tianjin, 300072, China.
| | - Zhuofan Xu
- Institute of Molecular Plus, Department of Chemistry, Tianjin University, 92 Weijin Road, Tianjin, 300072, China.
| | - Zhaofangzhou Pu
- Institute of Molecular Plus, Department of Chemistry, Tianjin University, 92 Weijin Road, Tianjin, 300072, China.
| | - Sota Sato
- Department of Applied Chemistry, Integrated Molecular Structure Analysis Laboratory, Social Cooperation Program, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Xiaotao Zhang
- Institute of Molecular Aggregation Science, Tianjin University, Tianjin 300072, China.
| | - Wenping Hu
- Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Department of Chemistry, School of Science, Tianjin University, Tianjin 300072, China. .,Haihe Laboratory of Sustainable Chemical Transformations, Tianjin 300192, China
| | - Zhe Sun
- Institute of Molecular Plus, Department of Chemistry, Tianjin University, 92 Weijin Road, Tianjin, 300072, China. .,Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Department of Chemistry, School of Science, Tianjin University, Tianjin 300072, China. .,Haihe Laboratory of Sustainable Chemical Transformations, Tianjin 300192, China
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24
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Xu X, Takebayashi S, Hanayama H, Vasylevskyi S, Onishi T, Ohto T, Tada H, Narita A. 6,6'-Biindeno[1,2- b]anthracene: An Open-Shell Biaryl with High Diradical Character. J Am Chem Soc 2023; 145:3891-3896. [PMID: 36780241 DOI: 10.1021/jacs.2c13890] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
Abstract
We report in situ generation of a 6,6'-biindeno[1,2-b]anthracene (BIA) derivative as an open-shell biaryl with high diradical character, which could be identified by mass spectrometry, NMR spectroscopy, single-crystal X-ray analysis, UV-vis-NIR absorption spectroscopy, and electron paramagnetic resonance (EPR) spectroscopy. Theoretical calculations by various methods and variable-temperature EPR analyses were performed to tackle the elusive ground state of BIA diradical, suggesting a singlet ground state with a nearly degenerate triplet state. These results provide insight into the design of unique open-shell biaryls.
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Affiliation(s)
- Xiushang Xu
- Organic and Carbon Nanomaterials Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Kunigami-gun, Okinawa 904-0495, Japan
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Satoshi Takebayashi
- Science and Technology Group, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Kunigami-gun, Okinawa 904-0495, Japan
| | - Hiroki Hanayama
- Organic and Carbon Nanomaterials Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Kunigami-gun, Okinawa 904-0495, Japan
| | - Serhii Vasylevskyi
- Engineering Section, Research Support Division, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Kunigami-gun, Okinawa 904-0495, Japan
| | - Takatsugu Onishi
- Organic and Carbon Nanomaterials Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Kunigami-gun, Okinawa 904-0495, Japan
| | - Tatsuhiko Ohto
- Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan
- Center for Quantum Information and Quantum Biology, Institute for Open and Transdisciplinary Research Initiatives, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan
| | - Hirokazu Tada
- Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan
| | - Akimitsu Narita
- Organic and Carbon Nanomaterials Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Kunigami-gun, Okinawa 904-0495, Japan
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
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25
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Abdurahman A, Wang J, Zhao Y, Li P, Shen L, Peng Q. A Highly Stable Organic Luminescent Diradical. Angew Chem Int Ed Engl 2023; 62:e202300772. [PMID: 36781392 DOI: 10.1002/anie.202300772] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2023] [Revised: 02/11/2023] [Accepted: 02/13/2023] [Indexed: 02/15/2023]
Abstract
It is very challenging to obtain stable room-temperature luminescent open-shell singlet diradicals. Herein we report the first stable Müller's hydrocarbon TTM-PhTTM with luminescent properties. Variable-temperature electron paramagnetic resonance spectroscopy measurements and theoretical calculations show that TTM-PhTTM has an open-shell singlet ground state with a diradical character of 90 %. Because of a small singlet-triplet energy gap, the open-shell singlet ground state can be thermally excited to a triplet state. TTM-PhTTM shows room-temperature deep-red emission in various solutions. Unusually high stability of TTM-PhTTM was also observed owing to effective steric hindrance and spin delocalization. Our results are beneficial to the rational design and discovery of more stable luminescent diradical materials.
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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, P. R. 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
| | - Yihan Zhao
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Qianjin Avenue 2699, Changchun, 130012, P. R. 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, P. R. China
| | - Li Shen
- College of Chemical Engineering and Environmental Chemistry, Weifang University, Weifang, 261061, 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
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26
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Hayashi Y, Suzuki S, Suzuki T, Ishigaki Y. Dibenzotropylium-Capped Orthogonal Geometry Enabling Isolation and Examination of a Series of Hydrocarbons with Multiple 14π-Aromatic Units. J Am Chem Soc 2023; 145:2596-2608. [PMID: 36606368 PMCID: PMC9896550 DOI: 10.1021/jacs.2c12574] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
A series of six dications composed of pure hydrocarbons with one to six non-substituted 9,10-anthrylene units end-capped with two dibenzotropyliums were designed and synthesized to elucidate the electronic properties of huge oligo(9,10-anthrylene) backbones. Their structures were successfully determined by X-ray analyses even in the case of eight planar 14π-electron units, revealing that all dications adopt almost orthogonally twisted structures between neighboring units. Spectroscopic and voltammetric analyses show that neither the significant overlap of orbitals nor the delocalization of electrons between 14π-electron units occurs due to the orthogonally twisted geometry even in solution. As a result, sequential oxidation processes were observed with the reversible formation of multivalent cations with the release of the same number of electrons as the number of anthrylene units. Upon two-electron reduction, a closed-shell butterfly-shaped form was obtained from the dication containing one anthrylene unit, whereas open-shell twisted biradicals were isolated as stable entities in the cases of derivatives containing three to six anthrylene units. Notably, from the derivative with two anthrylene units, a metastable open-shell isomer was obtained quantitatively and underwent slow thermal conversion to the most stable closed-shell isomer (Ea = 23.1 kcal mol-1). There is a drastic change in oxidation potentials between two neutral species (ΔE = 1.32 V in CH2Cl2). Since the present dications were regenerated upon oxidation of the isolated reduction products, these systems may contribute to the development of advanced response systems capable of switching color, magnetic properties, and oxidative properties by using a "cation-capped orthogonal geometry".
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Affiliation(s)
- Yuki Hayashi
- Department
of Chemistry, Faculty of Science, Hokkaido
University, Sapporo 060-0810, Japan
| | - Shuichi Suzuki
- Graduate
School of Engineering Science, Osaka University, Osaka 560-8531, Japan
| | - Takanori Suzuki
- Department
of Chemistry, Faculty of Science, Hokkaido
University, Sapporo 060-0810, Japan
| | - Yusuke Ishigaki
- Department
of Chemistry, Faculty of Science, Hokkaido
University, Sapporo 060-0810, Japan,
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27
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Dai Y, Xie Z, Bao M, Liu C, Su Y. Multiple stable redox states and tunable ground states via the marriage of viologens and Chichibabin's hydrocarbon †. Chem Sci 2023; 14:3548-3553. [PMID: 37006684 PMCID: PMC10056129 DOI: 10.1039/d3sc00102d] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2023] [Accepted: 02/28/2023] [Indexed: 03/30/2023] Open
Abstract
Chichibabin's hydrocarbon and viologens are among the most famous diradicaloids and organic redox systems, respectively. However, each has its own disadvantages: the instability of the former and its charged species, and the closed-shell nature of the neutral species derived from the latter, respectively. Herein, we report that terminal borylation and central distortion of 4,4′-bipyridine allow us to readily isolate the first bis-BN-based analogues (1 and 2) of Chichibabin's hydrocarbon with three stable redox states and tunable ground states. Electrochemically, both compounds exhibit two reversible oxidation processes with wide redox ranges. One- and two-electron chemical oxidations of 1 afford the crystalline radical cation 1˙+ and dication 12+, respectively. Moreover, the ground states of 1 and 2 are tunable with 1 as a closed-shell singlet and the tetramethyl-substituted 2 as an open-shell singlet, the latter of which could be thermally excited to its triplet state because of the small singlet-triplet gap. Herein, we report the isolation of bis-BN-based species 1 and 2 with multiple stable redox states. Their ground states are tunable with 1 as a closed-shell singlet and 2 as an open-shell singlet with a small singlet-triplet gap.![]()
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Affiliation(s)
- Yuyang Dai
- College of Chemistry, Chemical Engineering and Materials Science, School of Radiation Medicine and Protection, Soochow UniversitySuzhou 215123China
| | - Zhuofeng Xie
- College of Chemistry, Chemical Engineering and Materials Science, School of Radiation Medicine and Protection, Soochow UniversitySuzhou 215123China
| | - Manling Bao
- College of Chemistry, Chemical Engineering and Materials Science, School of Radiation Medicine and Protection, Soochow UniversitySuzhou 215123China
| | - Chunmeng Liu
- College of Chemistry, Chemical Engineering and Materials Science, School of Radiation Medicine and Protection, Soochow UniversitySuzhou 215123China
| | - Yuanting Su
- College of Chemistry, Chemical Engineering and Materials Science, School of Radiation Medicine and Protection, Soochow UniversitySuzhou 215123China
- State Key Laboratory of Coordination Chemistry, Nanjing UniversityNanjing 210023China
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28
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Kuriakose F, Commodore M, Hu C, Fabiano CJ, Sen D, Li RR, Bisht S, Üngör Ö, Lin X, Strouse GF, DePrince AE, Lazenby RA, Mentink-Vigier F, Shatruk M, Alabugin IV. Design and Synthesis of Kekulè and Non-Kekulè Diradicaloids via the Radical Periannulation Strategy: The Power of Seven Clar's Sextets. J Am Chem Soc 2022; 144:23448-23464. [PMID: 36516873 DOI: 10.1021/jacs.2c09637] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
This work introduces an approach to uncoupling electrons via maximum utilization of localized aromatic units, i.e., the Clar's π-sextets. To illustrate the utility of this concept to the design of Kekulé diradicaloids, we have synthesized a tridecacyclic polyaromatic system where a gain of five Clar's sextets in the open-shell form overcomes electron pairing and leads to the emergence of a high degree of diradical character. According to unrestricted symmetry-broken UCAM-B3LYP calculations, the singlet diradical character in this core system is characterized by the y0 value of 0.98 (y0 = 0 for a closed-shell molecule, y0 = 1 for pure diradical). The efficiency of the new design strategy was evaluated by comparing the Kekulé system with an isomeric non-Kekulé diradical of identical size, i.e., a system where the radical centers cannot couple via resonance. The calculated singlet-triplet gap, i.e., the ΔEST values, in both of these systems approaches zero: -0.3 kcal/mol for the Kekulé and +0.2 kcal/mol for the non-Kekulé diradicaloids. The target isomeric Kekulé and non-Kekulé systems were assembled using a sequence of radical periannulations, cross-coupling, and C-H activation. The diradicals are kinetically stabilized by six tert-butyl substituents and (triisopropylsilyl)acetylene groups. Both molecules are NMR-inactive but electron paramagnetic resonance (EPR)-active at room temperature. Cyclic voltammetry revealed quasi-reversible oxidation and reduction processes, consistent with the presence of two nearly degenerate partially occupied molecular orbitals. The experimentally measured ΔEST value of -0.14 kcal/mol confirms that K is, indeed, a nearly perfect singlet diradical.
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Affiliation(s)
- Febin Kuriakose
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida32306-4390, United States
| | - Michael Commodore
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida32306-4390, United States
| | - Chaowei Hu
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida32306-4390, United States
| | - Catherine J Fabiano
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida32306-4390, United States
| | - Debashis Sen
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida32306-4390, United States
| | - Run R Li
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida32306-4390, United States
| | - Shubham Bisht
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida32306-4390, United States
| | - Ökten Üngör
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida32306-4390, United States
| | - Xinsong Lin
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida32306-4390, United States
| | - Geoffrey F Strouse
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida32306-4390, United States
| | - A Eugene DePrince
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida32306-4390, United States
| | - Robert A Lazenby
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida32306-4390, United States
| | - Frederic Mentink-Vigier
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida32310, United States
| | - Michael Shatruk
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida32306-4390, United States
| | - Igor V Alabugin
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida32306-4390, United States
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29
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Baum TY, Fernández S, Peña D, van der Zant HSJ. Magnetic Fingerprints in an All-Organic Radical Molecular Break Junction. NANO LETTERS 2022; 22:8086-8092. [PMID: 36206381 PMCID: PMC9614975 DOI: 10.1021/acs.nanolett.2c02326] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 10/05/2022] [Indexed: 05/25/2023]
Abstract
Polycyclic aromatic hydrocarbons radicals are organic molecules with a nonzero total magnetic moment. Here, we report on charge-transport experiments with bianthracene-based radicals using a mechanically controlled break junction technique at low temperatures (6 K). The conductance spectra demonstrate that the magnetism of the diradical is preserved in solid-state devices and that it manifests itself either in the form of a Kondo resonance or inelastic electron tunneling spectroscopy signature caused by spin-flip processes. The magnetic fingerprints depend on the exact configuration of the molecule in the junction; this picture is supported by reference measurements on a radical molecule with the same backbone but with one free spin, in which only Kondo anomalies are observed. The results show that the open-shell structures based on the bianthracene core are interesting systems to study spin-spin interactions in solid-state devices, and this may open the way to control them either electrically or by mechanical strain.
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Affiliation(s)
- Thomas Y. Baum
- Kavli
Institute of Nanoscience, Delft University
of Technology, Lorentzweg 1, 2628 CJDelft, The Netherlands
| | - Saleta Fernández
- Centro
Singular de Investigación en Química Biolóxica
e Materiais Moleculares (CiQUS) and Departamento de Química
Orgánica, Universidade de Santiago
de Compostela, Santiago
de Compostela, Spain15782
| | - Diego Peña
- Centro
Singular de Investigación en Química Biolóxica
e Materiais Moleculares (CiQUS) and Departamento de Química
Orgánica, Universidade de Santiago
de Compostela, Santiago
de Compostela, Spain15782
| | - Herre S. J. van der Zant
- Kavli
Institute of Nanoscience, Delft University
of Technology, Lorentzweg 1, 2628 CJDelft, The Netherlands
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30
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Design of an open-shell nitrogen-centered diradicaloid with tunable stimuli-responsive electronic properties. Commun Chem 2022; 5:127. [PMID: 36697916 PMCID: PMC9814612 DOI: 10.1038/s42004-022-00747-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2022] [Accepted: 10/03/2022] [Indexed: 01/28/2023] Open
Abstract
Organic diradicaloids usually display an open-shell singlet ground state with significant singlet diradical character (y0) which endow them with intriguing physiochemical properties and wide applications. In this study, we present the design of an open-shell nitrogen-centered diradicaloid which can reversibly respond to multiple stimuli and display the tunable diradical character and chemo-physical properties. 1a was successfully synthesized through a simple and high-yielding two-step synthetic strategy. Both experimental and calculated results indicated that 1a displayed an open-shell singlet ground state with small singlet-triplet energy gap (ΔES-T = -2.311 kcal mol-1) and a modest diradical character (y0 = 0.60). Interestingly, 1a was demonstrated to undergo reversible Lewis acid-base reaction to form acid-base adducts, which was proven to effectively tune the ground-state electronic structures of 1a as well as its diradical character and spin density distributions. Based on this, we succeeded in devising a photoresponsive system based on 1a and a commercially available photoacid merocyanine (MEH). We believe that our studies including the molecular design methodology and the stimuli-responsive organic diradicaloid system will open up a new way to develop organic diradicaloids with tunable properties and even intelligent-responsive diradicaloid-based materials.
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31
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Gong Z, Xiang Q, Li K, Xu Z, Hu J, Ni Y, Sato S, Sun Z. Pentagon‐Containing
Doublet Graphene Fragments with
Edge‐Dependent
Spin/Charge Distribution. CHINESE J CHEM 2022. [DOI: 10.1002/cjoc.202200344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Zongcheng Gong
- Institute of Molecular Plus, Department of Chemistry Tianjin university 92 Weijin Road Tianjin 300072 China
| | - Qin Xiang
- Institute of Molecular Plus, Department of Chemistry Tianjin university 92 Weijin Road Tianjin 300072 China
| | - Ke Li
- Institute of Molecular Plus, Department of Chemistry Tianjin university 92 Weijin Road Tianjin 300072 China
| | - Zhuofan Xu
- Institute of Molecular Plus, Department of Chemistry Tianjin university 92 Weijin Road Tianjin 300072 China
| | - Jinlian Hu
- Institute of Molecular Plus, Department of Chemistry Tianjin university 92 Weijin Road Tianjin 300072 China
| | - Yong Ni
- Department of Chemistry Southern University of Science and Technology Shenzhen 518055 China
| | - Sota Sato
- Department of Applied Chemistry Integrated Molecular Structure Analysis Laboratory, Social Cooperation Program, The University of Tokyo
| | - Zhe Sun
- Institute of Molecular Plus, Department of Chemistry Tianjin university 92 Weijin Road Tianjin 300072 China
- Haihe Laboratory of Sustainable Chemical Transformations Tianjin 300192 China
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32
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Čavlović D, Häussinger D, Blacque O, Ravat P, Juríček M. Nonacethrene Unchained: A Cascade to Chiral Contorted Conjugated Hydrocarbon with Two sp 3-Defects. JACS AU 2022; 2:1616-1626. [PMID: 35911448 PMCID: PMC9326821 DOI: 10.1021/jacsau.2c00190] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We demonstrate that structurally complex carbon nanostructures can be achieved via a synthetic approach that capitalizes on a π-radical reaction cascade. The cascade is triggered by oxidation of a dihydro precursor of helical diradicaloid nonacethrene to give a chiral contorted polycyclic aromatic hydrocarbon named hypercethrene. In this ten-electron oxidation process, four σ-bonds, one π-bond, and three six-membered rings are formed in a sequence of up to nine steps to yield a 72-carbon-atom warped framework, comprising two configurationally locked [7]helicene units, a fluorescent peropyrene unit, and two precisely installed sp3-defects. The key intermediate in this cascade is a closed nonacethrene derivative with one quaternary sp3-center, presumably formed via an electrocyclic ring closure of nonacethrene, which, when activated by oxidation, undergoes a reaction cascade analogous to the oxidative dimerization of phenalenyl to peropyrene. By controlling the amount of oxidant used, two intermediates and one side product could be isolated and fully characterized, including single-crystal X-ray diffraction analysis, and two intermediates were detected by electron paramagnetic resonance spectroscopy. In concert with density functional theory calculations, these intermediates support the proposed reaction mechanism. Compared to peropyrene, the absorption and emission of hypercethrene are slightly red-shifted on account of extended π-conjugation and the fluorescence quantum yield of 0.45 is decreased by a factor of ∼2. Enantiomerically enriched hypercethrene displays circularly polarized luminescence with a brightness value of 8.3 M-1 cm-1. Our results show that reactions of graphene-based π-radicals-typically considered an "undefined decomposition" of non-zero-spin materials-can be well-defined and selective, and have potential to be transformed into a step-economic synthetic method toward complex carbon nanostructures.
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Affiliation(s)
- Daniel Čavlović
- Department
of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Daniel Häussinger
- Department
of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Olivier Blacque
- Department
of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Prince Ravat
- Department
of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
- Institute
of Organic Chemistry, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Michal Juríček
- Department
of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
- Department
of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
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33
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Shimizu A, Morikoshi T, Sugisaki K, Shiomi D, Sato K, Takui T, Shintani R. Synthesis and Isolation of a Kekulé Hydrocarbon with a Triplet Ground State. Angew Chem Int Ed Engl 2022; 61:e202205729. [DOI: 10.1002/anie.202205729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Indexed: 11/10/2022]
Affiliation(s)
- Akihiro Shimizu
- Division of Chemistry Department of Materials Engineering Science Graduate School of Engineering Science Osaka University Toyonaka, Osaka 560-8531 Japan
| | - Tetsuya Morikoshi
- Division of Chemistry Department of Materials Engineering Science Graduate School of Engineering Science Osaka University Toyonaka, Osaka 560-8531 Japan
| | - Kenji Sugisaki
- Department of Chemistry and Molecular Materials Science Graduate School of Science Osaka City University Sumiyoshi-ku, Osaka 558-8585 Japan
- JST PRESTO Kawaguchi, Saitama 332-0012 Japan
| | - Daisuke Shiomi
- Department of Chemistry and Molecular Materials Science Graduate School of Science Osaka City University Sumiyoshi-ku, Osaka 558-8585 Japan
| | - Kazunobu Sato
- Department of Chemistry and Molecular Materials Science Graduate School of Science Osaka City University Sumiyoshi-ku, Osaka 558-8585 Japan
| | - Takeji Takui
- Department of Chemistry and Molecular Materials Science Graduate School of Science Osaka City University Sumiyoshi-ku, Osaka 558-8585 Japan
| | - Ryo Shintani
- Division of Chemistry Department of Materials Engineering Science Graduate School of Engineering Science Osaka University Toyonaka, Osaka 560-8531 Japan
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34
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Wu F, Ma J, Lombardi F, Fu Y, Liu F, Huang Z, Liu R, Komber H, Alexandropoulos DI, Dmitrieva E, Lohr TG, Israel N, Popov AA, Liu J, Bogani L, Feng X. Benzo-Extended Cyclohepta[def]fluorene Derivatives with Very Low-Lying Triplet States. Angew Chem Int Ed Engl 2022; 61:e202202170. [PMID: 35290699 PMCID: PMC9324097 DOI: 10.1002/anie.202202170] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Indexed: 12/24/2022]
Abstract
Open-shell non-alternant polycyclic hydrocarbons (PHs) are attracting increasing attention due to their promising applications in organic spintronics and quantum computing. Herein we report the synthesis of three cyclohepta[def]fluorene-based diradicaloids (1-3), by fusion of benzo rings on its periphery for the thermodynamic stabilization, as evidenced by multiple characterization techniques. Remarkably, all of them display a very narrow optical energy gap (Eg opt =0.52-0.69 eV) and persistent stability under ambient conditions (t1/2 =11.7-33.3 h). More importantly, this new type of diradicaloids possess a low-lying triplet state with an extremely small singlet-triplet energy gap, as low as 0.002 kcal mol-1 , with a clear dependence on the molecular size. This family of compounds thus offers a new route to create non-alternant open-shell PHs with high-spin ground states, and opens up novel possibilities and insights into understanding the structure-property relationships.
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Affiliation(s)
- Fupeng Wu
- Center for Advancing Electronics Dresden (cfaed) & Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, Mommsenstrasse 4, 01062, Dresden, Germany
| | - Ji Ma
- Center for Advancing Electronics Dresden (cfaed) & Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, Mommsenstrasse 4, 01062, Dresden, Germany
| | | | - Yubin Fu
- Center for Advancing Electronics Dresden (cfaed) & Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, Mommsenstrasse 4, 01062, Dresden, Germany
| | - Fupin Liu
- Leibniz Institute for Solid State and Materials Research, 01069, Dresden, Germany
| | - Zhijie Huang
- Department of Materials, University of Oxford, Oxford, OX1 3PH, UK
| | - Renxiang Liu
- Center for Advancing Electronics Dresden (cfaed) & Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, Mommsenstrasse 4, 01062, Dresden, Germany
| | - Hartmut Komber
- Leibniz-Institut für Polymerforschung Dresden e. V., Hohe Straße 6, 01069, Dresden, Germany
| | | | - Evgenia Dmitrieva
- Leibniz Institute for Solid State and Materials Research, 01069, Dresden, Germany
| | - Thorsten G Lohr
- Center for Advancing Electronics Dresden (cfaed) & Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, Mommsenstrasse 4, 01062, Dresden, Germany
| | - Noel Israel
- Leibniz Institute for Solid State and Materials Research, 01069, Dresden, Germany
| | - Alexey A Popov
- Leibniz Institute for Solid State and Materials Research, 01069, Dresden, Germany
| | - Junzhi Liu
- Department of Chemistry and State Key Laboratory of Synthetic Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Lapo Bogani
- Department of Materials, University of Oxford, Oxford, OX1 3PH, UK
| | - Xinliang Feng
- Center for Advancing Electronics Dresden (cfaed) & Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, Mommsenstrasse 4, 01062, Dresden, Germany.,Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle, Germany
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35
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Shimizu A, Morikoshi T, Sugisaki K, Shiomi D, Sato K, Takui T, Shintani R. Synthesis and Isolation of a Kekulé Hydrocarbon with a Triplet Ground State. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202205729] [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)
- Akihiro Shimizu
- Division of Chemistry Department of Materials Engineering Science Graduate School of Engineering Science Osaka University Toyonaka, Osaka 560-8531 Japan
| | - Tetsuya Morikoshi
- Division of Chemistry Department of Materials Engineering Science Graduate School of Engineering Science Osaka University Toyonaka, Osaka 560-8531 Japan
| | - Kenji Sugisaki
- Department of Chemistry and Molecular Materials Science Graduate School of Science Osaka City University Sumiyoshi-ku, Osaka 558-8585 Japan
- JST PRESTO Kawaguchi, Saitama 332-0012 Japan
| | - Daisuke Shiomi
- Department of Chemistry and Molecular Materials Science Graduate School of Science Osaka City University Sumiyoshi-ku, Osaka 558-8585 Japan
| | - Kazunobu Sato
- Department of Chemistry and Molecular Materials Science Graduate School of Science Osaka City University Sumiyoshi-ku, Osaka 558-8585 Japan
| | - Takeji Takui
- Department of Chemistry and Molecular Materials Science Graduate School of Science Osaka City University Sumiyoshi-ku, Osaka 558-8585 Japan
| | - Ryo Shintani
- Division of Chemistry Department of Materials Engineering Science Graduate School of Engineering Science Osaka University Toyonaka, Osaka 560-8531 Japan
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36
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Günther K, Grabicki N, Battistella B, Grubert L, Dumele O. An All-Organic Photochemical Magnetic Switch with Bistable Spin States. J Am Chem Soc 2022; 144:8707-8716. [PMID: 35522997 DOI: 10.1021/jacs.2c02195] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Controlling the electronic spin state in single molecules through an external stimulus is of interest in developing devices for information technology, such as data storage and quantum computing. We report the synthesis and operation mode of two all-organic molecular spin-state switches that can be photochemically switched from a diamagnetic [electron paramagnetic resonance (EPR)-silent] to a paramagnetic (EPR-active) form at cryogenic temperatures due to a reversible electrocyclic reaction of its carbon skeleton. Facile synthetic substitution of a configurationally stable 1,14-dimethyl-[5]helicene with radical stabilizing groups at the 4,11-positions afforded two spin-state switches as 4,11-dioxo or 4,11-bis(dicyanomethylidenyl) derivatives in a closed diamagnetic form. After irradiation with an LED light source at cryogenic temperatures, a stable paramagnetic state is readily obtained, making this system a bistable magnetic switch that can reversibly react back to its diamagnetic form through a thermal stimulus. The switching can be monitored with UV/vis spectroscopy and EPR spectroscopy or induced by electrochemical reduction and reoxidation. Variable-temperature EPR spectroscopy of the paramagnetic species revealed an open-shell triplet ground state with an experimentally determined triplet-singlet energy gap of ΔET-S < 0.1 kcal mol-1. The inherent chirality and the ability to separate the enantiomers turns this helical motif into a potential chiroptical spin-state switch. The herein developed 4,11-substitution pattern on the dimethyl[5]helicene introduces a platform for designing future generations of organic molecular photomagnetic switches that might find applications in spintronics and related fields.
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Affiliation(s)
- Konstantin Günther
- Department of Chemistry & IRIS Adlershof, Humboldt University of Berlin, Brook-Taylor-Strasse 2, Berlin D-12489, Germany
| | - Niklas Grabicki
- Department of Chemistry & IRIS Adlershof, Humboldt University of Berlin, Brook-Taylor-Strasse 2, Berlin D-12489, Germany
| | - Beatrice Battistella
- Department of Chemistry & IRIS Adlershof, Humboldt University of Berlin, Brook-Taylor-Strasse 2, Berlin D-12489, Germany
| | - Lutz Grubert
- Department of Chemistry & IRIS Adlershof, Humboldt University of Berlin, Brook-Taylor-Strasse 2, Berlin D-12489, Germany
| | - Oliver Dumele
- Department of Chemistry & IRIS Adlershof, Humboldt University of Berlin, Brook-Taylor-Strasse 2, Berlin D-12489, Germany
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37
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Nishiuchi T, Aibara S, Sato H, Kubo T. Synthesis of π-Extended Thiele’s and Chichibabin’s Hydrocarbons and Effect of the π-Congestion on Conformations and Electronic States. J Am Chem Soc 2022; 144:7479-7488. [PMID: 35426674 PMCID: PMC9136924 DOI: 10.1021/jacs.2c02318] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
![]()
The
biradicaloid of Chichibabin’s hydrocarbon exits in a
unique thermal equilibrium between closed-shell singlet and open-shell
triplet forms. Conceptually, the incorporation of nonplanar aromatic
groups, such as anthraquinodimethane (AQD), in these species could
bring about stabilization of the individual singlet and triplet spin
biradicaloids by creating a high energy barrier for conformational
interconversion between folded (singlet) and twisted (triplet) forms.
Moreover, this alteration could introduce the possibility of controlling
spin states through conformational changes induced by chemical and
physical processes. Herein, we report the preparation of AQD-containing,
π-extended Thiele’s (A-TH) and Chichibabin’s
(A-CH) hydrocarbons, which have highly π-congested
structures resulting from the presence of bulky 9-anthryl units. The
π-congestion in these substances leads to steric frustration
about carbon–carbon double bonds and creates flexible dynamic
motion with a moderate activation barrier between folded singlet and
twisted triplet states. These constraints make it possible to isolate
the twisted triplet state of A-CH. In addition, simple
mechanical grinding of the folded singlet of A-CH produces
the twisted triplet.
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Affiliation(s)
- Tomohiko Nishiuchi
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
- Innovative Catalysis Science Division, Institute for Open and Transdisciplinary Research Initiatives, (ICS-OTRI), Osaka University, Suita, Osaka 565-0871, Japan
| | - Seito Aibara
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Hiroyasu Sato
- Rigaku Corporation, 3-9-12 Matsubara, Akishima, Tokyo 196-8666, Japan
| | - Takashi Kubo
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
- Innovative Catalysis Science Division, Institute for Open and Transdisciplinary Research Initiatives, (ICS-OTRI), Osaka University, Suita, Osaka 565-0871, Japan
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38
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Wu F, Ma J, Lombardi F, Fu Y, Liu F, Huang Z, Liu R, Komber H, Alexandropoulos DI, Dmitrieva E, Lohr TG, Israel N, Popov AA, Liu J, Bogani L, Feng X. Benzo‐Extended Cyclohepta[
def
]fluorene Derivatives with Very Low‐Lying Triplet States. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202202170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Fupeng Wu
- Center for Advancing Electronics Dresden (cfaed) & Faculty of Chemistry and Food Chemistry Technische Universität Dresden Mommsenstrasse 4 01062 Dresden Germany
| | - Ji Ma
- Center for Advancing Electronics Dresden (cfaed) & Faculty of Chemistry and Food Chemistry Technische Universität Dresden Mommsenstrasse 4 01062 Dresden Germany
| | | | - Yubin Fu
- Center for Advancing Electronics Dresden (cfaed) & Faculty of Chemistry and Food Chemistry Technische Universität Dresden Mommsenstrasse 4 01062 Dresden Germany
| | - Fupin Liu
- Leibniz Institute for Solid State and Materials Research 01069 Dresden Germany
| | - Zhijie Huang
- Department of Materials University of Oxford Oxford OX1 3PH UK
| | - Renxiang Liu
- Center for Advancing Electronics Dresden (cfaed) & Faculty of Chemistry and Food Chemistry Technische Universität Dresden Mommsenstrasse 4 01062 Dresden Germany
| | - Hartmut Komber
- Leibniz-Institut für Polymerforschung Dresden e. V. Hohe Straße 6 01069 Dresden Germany
| | | | - Evgenia Dmitrieva
- Leibniz Institute for Solid State and Materials Research 01069 Dresden Germany
| | - Thorsten G. Lohr
- Center for Advancing Electronics Dresden (cfaed) & Faculty of Chemistry and Food Chemistry Technische Universität Dresden Mommsenstrasse 4 01062 Dresden Germany
| | - Noel Israel
- Leibniz Institute for Solid State and Materials Research 01069 Dresden Germany
| | - Alexey A. Popov
- Leibniz Institute for Solid State and Materials Research 01069 Dresden Germany
| | - Junzhi Liu
- Department of Chemistry and State Key Laboratory of Synthetic Chemistry The University of Hong Kong Pokfulam Road Hong Kong China
| | - Lapo Bogani
- Department of Materials University of Oxford Oxford OX1 3PH UK
| | - Xinliang Feng
- Center for Advancing Electronics Dresden (cfaed) & Faculty of Chemistry and Food Chemistry Technische Universität Dresden Mommsenstrasse 4 01062 Dresden Germany
- Max Planck Institute of Microstructure Physics Weinberg 2 06120 Halle Germany
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39
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Nishiuchi T, Ishii D, Aibara S, Sato H, Kubo T. Synthesis, properties and chemical modification of a persistent triisopropylsilylethynyl substituted tri(9-anthryl)methyl radical. Chem Commun (Camb) 2022; 58:3306-3309. [PMID: 35178540 DOI: 10.1039/d2cc00548d] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
In studies aimed at developing new organic spin materials, we prepared a triisopropylsilylethynyl substituted tri(9-anthryl)methyl (TAntM) radical. The TIPS-ethynyl group in this radical effectively suppresses its reactivity, resulting in extremely high stability in air for at least one month. Chemical modification of the radical using [4+2] Diels-Alder reaction proceeds even at room temperature. Because harsh conditions and metal-catalyzed reactions are not required, this post-modification strategy should be highly versatile for use in constructing unique spin-labelled molecules.
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Affiliation(s)
- Tomohiko Nishiuchi
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan. .,Innovative Catalysis Science Division, Institute for Open and Transdisciplinary Research Initiatives, (ICS-OTRI), Osaka University, Suita, Osaka 565-0871, Japan
| | - Daisuke Ishii
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.
| | - Seito Aibara
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.
| | - Hiroyasu Sato
- Rigaku Corporation, 3-9-12 Matsubara, Akishima, Tokyo 196-8666, Japan
| | - Takashi Kubo
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan. .,Innovative Catalysis Science Division, Institute for Open and Transdisciplinary Research Initiatives, (ICS-OTRI), Osaka University, Suita, Osaka 565-0871, Japan
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40
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Mishra S, Fatayer S, Fernández S, Kaiser K, Peña D, Gross L. Nonbenzenoid High-Spin Polycyclic Hydrocarbons Generated by Atom Manipulation. ACS NANO 2022; 16:3264-3271. [PMID: 35130690 DOI: 10.1021/acsnano.1c11157] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
We report the on-surface synthesis of a nonbenzenoid triradical through dehydrogenation of truxene (C27H18) on coinage metal and insulator surfaces. Voltage pulses applied via the tip of a combined scanning tunneling microscope/atomic force microscope were used to cleave individual C-H bonds in truxene. The resultant final product truxene-5,10,15-triyl (1) was characterized at the single-molecule scale using a combination of atomic force microscopy, scanning tunneling microscopy, and scanning tunneling spectroscopy. Our analyses show that 1 retains its open-shell quartet ground state, predicted by density functional theory, on a two monolayer-thick NaCl layer on a Cu(111) surface. We image the frontier orbital densities of 1 and confirm that they correspond to spin-split singly occupied molecular orbitals. Through our synthetic strategy, we also isolate two reactive intermediates toward the synthesis of 1, derivatives of fluorenyl radical and indeno[1,2-a]fluorene, with predicted open-shell doublet and triplet ground states, respectively. Our results should have bearings on the synthesis of nonbenzenoid high-spin polycyclic frameworks with magnetism beyond Lieb's theorem.
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Affiliation(s)
| | | | - Saleta Fernández
- Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS) and Departamento de Química Orgánica, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | | | - Diego Peña
- Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS) and Departamento de Química Orgánica, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - Leo Gross
- IBM Research-Zurich, 8803 Rüschlikon, Switzerland
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41
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Li K, Xu Z, Xu J, Weng T, Chen X, Sato S, Wu J, Sun Z. Overcrowded Ethylene-Bridged Nanohoop Dimers: Regioselective Synthesis, Multiconfigurational Electronic States, and Global Hückel/Möbius Aromaticity. J Am Chem Soc 2021; 143:20419-20430. [PMID: 34817177 DOI: 10.1021/jacs.1c10170] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The design and preparation of molecular systems with multiple geometric and electronic configurations are the cornerstones for multifunctional materials with stimuli-responsive behaviors. We describe here the regioselective and facile synthesis of two types of overcrowded ethylene-bridged nanohoop dimers, with folded and twisted geometric structures as well as closed-shell, diradical and dication electronic structures. The strained nanohoop structures have a profound effect on the overall molecular and electronic configurations, which resulted in the destabilized diradical state. X-ray crystallographic analysis revealed the folded molecular geometry for the neutral species and twisted geometry for the dication species. The unique molecular dynamics, optical properties, and dynamic redox properties were disclosed in the solution phase by spectroscopic and electrochemical methods. Furthermore, the global Hückel and Möbius aromaticity were revealed by a combination of experimental and theoretical approaches. Our studies shed light on the design of nanohoop-incorporated multiconfigurational materials with unique topologies and functions.
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Affiliation(s)
- Ke Li
- Institute of Molecular Plus, Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Tianjin University, 92 Weijin Road, Tianjin 300072, China
| | - Zhuofan Xu
- Institute of Molecular Plus, Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Tianjin University, 92 Weijin Road, Tianjin 300072, China
| | - Jun Xu
- Health Science Platform, Tianjin University, 92 Weijin Road, Tianjin 300072, China
| | - Taoyu Weng
- Institute of Molecular Plus, Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Tianjin University, 92 Weijin Road, Tianjin 300072, China
| | - Xing Chen
- Institute of Molecular Plus, Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Tianjin University, 92 Weijin Road, Tianjin 300072, China
| | - Sota Sato
- Department of Applied Chemistry, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Jishan Wu
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543
| | - Zhe Sun
- Institute of Molecular Plus, Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Tianjin University, 92 Weijin Road, Tianjin 300072, China
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42
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Maiti A, Sobottka S, Chandra S, Jana D, Ravat P, Sarkar B, Jana A. Diamidocarbene-Based Thiele and Tschitschibabin Hydrocarbons: Carbonyl Functionalized Kekulé Diradicaloids. J Org Chem 2021; 86:16464-16472. [PMID: 34780693 DOI: 10.1021/acs.joc.1c01827] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Herein, we report diamidocarbene (DAC)-based Thiele and Tschitschibabin hydrocarbons, diradicaloids that contain four carbonyl/amido functional groups. The impact of two different π-conjugated spacers, p-phenylene vs p,p'-biphenylene, has been realized. The quantum chemical calculations suggest diamidocarbene (DAC)-based Thiele hydrocarbon (p-phenylene bridged) closed-shell singlet is the ground state, whereas for the diamidocarbene (DAC)-based Tschitschibabin hydrocarbon (p,p'-biphenylene bridged), open-shell singlet is the ground state. The influence of two different π-conjugated spacers also has been reflected in their UV-vis spectra. To gain more information on the diamidocarbene (DAC)-based Thiele and Tschitschibabin hydrocarbons, we have also carried out cyclic voltammetry investigations along with UV-vis-NIR-spectroelectrochemical studies of their corresponding 2-e oxidized product.
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Affiliation(s)
- Avijit Maiti
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad 500046, Telangana, India
| | - Sebastian Sobottka
- Institut für Chemie und Biochemie, Anorganische Chemie, Freie Universität Berlin, Fabeckstraße 34-36, 14195 Berlin, Germany
| | - Shubhadeep Chandra
- Institut für Chemie und Biochemie, Anorganische Chemie, Freie Universität Berlin, Fabeckstraße 34-36, 14195 Berlin, Germany.,Universität Stuttgart, Fakultät Chemie, Lehrstuhl für Anorganische Koordinationschemie, Institut für Anorganische Chemie, Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Debayan Jana
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad 500046, Telangana, India
| | - Prince Ravat
- Institute of Organic Chemistry, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Biprajit Sarkar
- Institut für Chemie und Biochemie, Anorganische Chemie, Freie Universität Berlin, Fabeckstraße 34-36, 14195 Berlin, Germany.,Universität Stuttgart, Fakultät Chemie, Lehrstuhl für Anorganische Koordinationschemie, Institut für Anorganische Chemie, Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Anukul Jana
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad 500046, Telangana, India
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43
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Liu T, Qi C, Zhou Q, Dai W, Lan Y, Xu L, Ren J, Pan Y, Yang L, Ge Y, Qu YK, Li W, Li H, Xiao S. Divergent Synthesis of Contorted Polycyclic Aromatics Containing Pentagons, Heptagon, and/or Azulene. Org Lett 2021; 24:472-477. [PMID: 34797076 DOI: 10.1021/acs.orglett.1c03498] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Divergent synthesis of four contorted aromatics containing pentagons, a heptagon, and/or an azulene from the same difluorenyl pentacenediene precursor were realized in one step. The subtle differences in molecular structure were confirmed by X-ray crystallography. The mechanisms for the control of different products, which involve a ring-expansion rearrangement, Scholl reactions, and/or Mallory cyclization were proposed on the basis of control experiments and DFT calculations. Such development adds good structure versatility and materials accessibility to the study of contorted aromatics.
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Affiliation(s)
- Taifeng Liu
- The Education Ministry Key Lab of Resource Chemistry, Joint International Research Laboratory of Resource Chemistry, Ministry of Education, Shanghai Key Laboratory of Rare Earth Functional Materials, College of Chemistry and Materials Science, Shanghai Normal University, Shanghai 200234, China
| | - Chaoran Qi
- The Education Ministry Key Lab of Resource Chemistry, Joint International Research Laboratory of Resource Chemistry, Ministry of Education, Shanghai Key Laboratory of Rare Earth Functional Materials, College of Chemistry and Materials Science, Shanghai Normal University, Shanghai 200234, China
| | - Qinghai Zhou
- The Education Ministry Key Lab of Resource Chemistry, Joint International Research Laboratory of Resource Chemistry, Ministry of Education, Shanghai Key Laboratory of Rare Earth Functional Materials, College of Chemistry and Materials Science, Shanghai Normal University, Shanghai 200234, China
| | - Wenying Dai
- The Education Ministry Key Lab of Resource Chemistry, Joint International Research Laboratory of Resource Chemistry, Ministry of Education, Shanghai Key Laboratory of Rare Earth Functional Materials, College of Chemistry and Materials Science, Shanghai Normal University, Shanghai 200234, China
| | - Yuying Lan
- The Education Ministry Key Lab of Resource Chemistry, Joint International Research Laboratory of Resource Chemistry, Ministry of Education, Shanghai Key Laboratory of Rare Earth Functional Materials, College of Chemistry and Materials Science, Shanghai Normal University, Shanghai 200234, China
| | - Lanting Xu
- The Education Ministry Key Lab of Resource Chemistry, Joint International Research Laboratory of Resource Chemistry, Ministry of Education, Shanghai Key Laboratory of Rare Earth Functional Materials, College of Chemistry and Materials Science, Shanghai Normal University, Shanghai 200234, China
| | - Junxia Ren
- The Education Ministry Key Lab of Resource Chemistry, Joint International Research Laboratory of Resource Chemistry, Ministry of Education, Shanghai Key Laboratory of Rare Earth Functional Materials, College of Chemistry and Materials Science, Shanghai Normal University, Shanghai 200234, China
| | - Yangyang Pan
- The Education Ministry Key Lab of Resource Chemistry, Joint International Research Laboratory of Resource Chemistry, Ministry of Education, Shanghai Key Laboratory of Rare Earth Functional Materials, College of Chemistry and Materials Science, Shanghai Normal University, Shanghai 200234, China
| | - Lei Yang
- The Education Ministry Key Lab of Resource Chemistry, Joint International Research Laboratory of Resource Chemistry, Ministry of Education, Shanghai Key Laboratory of Rare Earth Functional Materials, College of Chemistry and Materials Science, Shanghai Normal University, Shanghai 200234, China
| | - Yongchao Ge
- The Education Ministry Key Lab of Resource Chemistry, Joint International Research Laboratory of Resource Chemistry, Ministry of Education, Shanghai Key Laboratory of Rare Earth Functional Materials, College of Chemistry and Materials Science, Shanghai Normal University, Shanghai 200234, China
| | - Yang-Kun Qu
- The Education Ministry Key Lab of Resource Chemistry, Joint International Research Laboratory of Resource Chemistry, Ministry of Education, Shanghai Key Laboratory of Rare Earth Functional Materials, College of Chemistry and Materials Science, Shanghai Normal University, Shanghai 200234, China
| | - Wenhua Li
- The Education Ministry Key Lab of Resource Chemistry, Joint International Research Laboratory of Resource Chemistry, Ministry of Education, Shanghai Key Laboratory of Rare Earth Functional Materials, College of Chemistry and Materials Science, Shanghai Normal University, Shanghai 200234, China
| | - Hexing Li
- The Education Ministry Key Lab of Resource Chemistry, Joint International Research Laboratory of Resource Chemistry, Ministry of Education, Shanghai Key Laboratory of Rare Earth Functional Materials, College of Chemistry and Materials Science, Shanghai Normal University, Shanghai 200234, China
| | - Shengxiong Xiao
- The Education Ministry Key Lab of Resource Chemistry, Joint International Research Laboratory of Resource Chemistry, Ministry of Education, Shanghai Key Laboratory of Rare Earth Functional Materials, College of Chemistry and Materials Science, Shanghai Normal University, Shanghai 200234, China
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44
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Wonink MBS, Corbet BP, Kulago AA, Boursalian GB, de Bruin B, Otten E, Browne WR, Feringa BL. Three-State Switching of an Anthracene Extended Bis-thiaxanthylidene with a Highly Stable Diradical State. J Am Chem Soc 2021; 143:18020-18028. [PMID: 34695359 PMCID: PMC8569810 DOI: 10.1021/jacs.1c05938] [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] [Indexed: 01/11/2023]
Abstract
A multistable molecular switching system based on an anthracene-extended bis-thiaxanthylidene with three individually addressable states that can be interconverted by electrochemical, thermal, and photochemical reactions is reported. Besides reversible switching between an open-shell diradical- and a closed-shell electronic configuration, our findings include a third dicationic state and control by multiple actuators. This dicationic state with an orthogonal conformation can be switched electrochemically with the neutral open-shell triplet state with orthogonal conformation, which was characterized by EPR. The remarkably stable diradical shows kinetic stability as a result of a significant activation barrier for isomerization to a more stable neutral closed-shell folded geometry. We ascribe this activation barrier of ΔG⧧(293 K) = 25.7 kcal mol-1 to steric hindrance in the fjord region of the overcrowded alkene structure. The folded closed-shell state can be converted back to the diradical state by irradiation with 385 nm. The folded state can also be oxidized to the dicationic state. These types of molecules with multiple switchable states and in particular stable diradicals show great potential in the design of new functional materials such as memory devices, logic gates, and OFETs.
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Affiliation(s)
- Marco B S Wonink
- Stratingh Institute for Chemistry and Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Brian P Corbet
- Stratingh Institute for Chemistry and Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Artem A Kulago
- Stratingh Institute for Chemistry and Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Gregory B Boursalian
- Stratingh Institute for Chemistry and Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Bas de Bruin
- Van't Hoff Institute for Molecular Sciences (HIMS), University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - Edwin Otten
- Stratingh Institute for Chemistry and Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Wesley R Browne
- Stratingh Institute for Chemistry and Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Ben L Feringa
- Stratingh Institute for Chemistry and Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
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45
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Han H, Zhang D, Zhu Z, Wei R, Xiao X, Wang X, Liu Y, Ma Y, Zhao D. Aromatic Stacking Mediated Spin-Spin Coupling in Cyclophane-Assembled Diradicals. J Am Chem Soc 2021; 143:17690-17700. [PMID: 34637282 DOI: 10.1021/jacs.1c08262] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
To investigate the capability of π-π stacking motifs to enable spin-spin coupling, we designed and synthesized three pairs of regio-isomers featuring two radical moieties joined by a [2.2]paracyclophane (CP) unit. By fusing indeno units to CP, two partially stacked fluorene radicals are covalently linked, exhibiting evident antiferromagnetic (AFM) coupling regardless of the orientation of two spins. Remarkably, while possessing high diradical indices of 0.8 and 0.9, the two molecules demonstrate good air stability by virtue of their singlet ground state. Single crystals help unravel the structural basis of their AFM coupling behaviors. When two radical centers are arranged at the pseudometa-positions around CP, the face-to-face stacked phenylene rings intrinsically confer orbital interactions that promote AFM coupling. On the other hand, if two radicals are directed in the pseudopara-orientation, significant orbital overlapping is observed between the radical centers (i.e., C9 of fluorene) and the aromatic carbons laid on the side, rendering AFM coupling between the two spins. In contrast, when two fluorene radicals are tethered to CP via C9 through a single C-C bond, ferromagnetic (FM) coupling is manifested by both diradical isomers featuring pseudometa- and pseudopara-connectivity. With minimal spin distributed on CP and thus limited contribution from π-π stacking, their spin-spin coupling properties are more similar to a pair of nitroxide diradical analogues, in which the two spins are dominantly coupled via through-space interactions. From these results, important conclusions are elucidated such as that although through-space interactions may confer FM coupling, with weakened strength shown by PAH radicals due to their lower polarity, face-to-face stacked π-frameworks tend to induce AFM coupling, because favorable orbital interactions are readily achieved by PAH systems hosting delocalized spins that are capable of adopting varied stacking motifs.
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Affiliation(s)
- Han Han
- 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 100871, 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 100871, China
| | - 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 100871, China
| | - Rong Wei
- 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 100871, 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 100871, China
| | - Xiaoge 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 100871, China
| | - Yiming Liu
- 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 100871, China
| | - Yuguo Ma
- 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 100871, 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 100871, China
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46
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Zhao J, Li X, Han YF. Air-/Heat-Stable Crystalline Carbon-Centered Radicals Derived from an Annelated N-Heterocyclic Carbene. J Am Chem Soc 2021; 143:14428-14432. [PMID: 34469133 DOI: 10.1021/jacs.1c06464] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Organic radicals are open-shell species and have been extensively applied to functional materials due to their unique physicochemical properties with unpaired electrons; however, most of them are highly reactive and short-lived. Herein, a series of stable radicals were readily accessed in two steps from a bis(imino)acenaphthene-supported N-heterocyclic carbene (IPr(BIAN)) through enhancing the delocalization of spin density. The IPr(BIAN)-based radicals 3a-c, obtained by reduction of the corresponding iminium salts 2a-c with KC8, have been spectroscopically and crystallographically (3a,c) characterized. DFT calculations indicate that increasing the electron-withdrawing properties of the para substituent on the carbene carbon atom results in the spin density evolving from the acenaphthene ring to the phenyl ring. The IPr(BIAN)-based radicals 3a-c show excellent stability: they have half-lives of 1 week in well-aerated solutions and feature a high thermal decomposition temperature up to 200 °C.
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Affiliation(s)
- Jing Zhao
- Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an 710127, People's Republic of China
| | - Xin Li
- Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an 710127, People's Republic of China
| | - Ying-Feng Han
- Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an 710127, People's Republic of China
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47
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Mutoh K, Toshimitsu S, Kobayashi Y, Abe J. Dynamic Spin-Spin Interaction Observed as Interconversion of Chemical Bonds in Stepwise Two-Photon Induced Photochromic Reaction. J Am Chem Soc 2021; 143:13917-13928. [PMID: 34427084 DOI: 10.1021/jacs.1c06775] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Biradicaloids in π-conjugated organic molecules have been extensively studied in recent years because of the fundamental insights into the chemical bonds and unique optical, electrical, and magnetic properties. Several studies have reported that the spin-spin interactions of biradicaloids with flexible molecular frameworks dynamically evolve correlating with molecular structural changes. Although these dynamic behaviors will provide important insights into the relationship between molecular structures and spin properties, studies on such behaviors have been limited to two-spin systems. Here, we investigated the stepwise photochromic properties of biphotochromic molecules involving multiple spin interactions by double-pulse laser flash photolysis. The one-photon photochromic reaction generates the o-biradical form as the open-closed form, which thermally isomerizes to the o-quinoidal form and reaches the thermal equilibrium state between them. The additional absorption of a photon by the open-closed form leads to the photochromic reaction of the other photochromic unit, resulting in the generation of unpaired spins at the p-position of the central aromatic bridge of the biradical or quinoidal form. Under the situation, while the interaction between the unpaired spins and the o-biradical preferentially produces the p-quinoidal form in which the antiferromagnetic interaction at the p-position is dominant, that between the spins and the o-quinoidal form kinetically produces the bis(o-quinoidal) form followed by the thermal isomerization to the thermodynamically stable p-quinoidal form. These dynamic spin-spin interactions along with the rearrangement of chemical bonds will give a deeper understanding of the singlet biradicaloids and that to bridge organic multiradicals in molecular systems to cooperative spin behaviors in bulk materials.
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Affiliation(s)
- Katsuya Mutoh
- Department of Chemistry, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara, Kanagawa 252-5258, Japan
| | - Shota Toshimitsu
- Department of Chemistry, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara, Kanagawa 252-5258, Japan
| | - Yoichi Kobayashi
- Department of Applied Chemistry, College of Life Sciences, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga 525-8577, Japan
| | - Jiro Abe
- Department of Chemistry, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara, Kanagawa 252-5258, Japan
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48
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Deng X, Liu X, Wei L, Ye T, Yu X, Zhang C, Xiao J. Pentagon-Containing π-Expanded Systems: Synthesis and Photophysical Properties. J Org Chem 2021; 86:9961-9969. [PMID: 34279110 DOI: 10.1021/acs.joc.1c00332] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We have designed and synthesized three novel twistacene-modified enlarged pentagon-containing π-systems (6 and 9) with mismatched structures. The introduction of electron-withdrawing cyclopenta rings in the parent skeleton effectively stabilizes the electron-rich arenes. Their optoelectronic properties were studied via ultraviolet-visible (UV-vis) absorption spectra, fluorescence spectra, cyclic voltammetry, and density functional theory (DFT) calculation. In addition, chemical oxidation of the as-prepared compounds with nitrosonium hexafluoroantimonate could form the corresponding cationic radicals.
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Affiliation(s)
- Xin Deng
- College of Chemistry and Environmental Science, Key Laboratory of Chemical Biology of Hebei Province, Key Laboratory of Medicinal Chemistry and Molecular Diagnosis, Ministry of Education Hebei University, Baoding 071002, P. R. China
| | - Xinqun Liu
- College of Chemistry and Environmental Science, Key Laboratory of Chemical Biology of Hebei Province, Key Laboratory of Medicinal Chemistry and Molecular Diagnosis, Ministry of Education Hebei University, Baoding 071002, P. R. China
| | - Leping Wei
- College of Chemistry and Environmental Science, Key Laboratory of Chemical Biology of Hebei Province, Key Laboratory of Medicinal Chemistry and Molecular Diagnosis, Ministry of Education Hebei University, Baoding 071002, P. R. China
| | - Tongtong Ye
- College of Chemistry and Environmental Science, Key Laboratory of Chemical Biology of Hebei Province, Key Laboratory of Medicinal Chemistry and Molecular Diagnosis, Ministry of Education Hebei University, Baoding 071002, P. R. China
| | - Xiaohui Yu
- College of Chemistry and Environmental Science, Key Laboratory of Chemical Biology of Hebei Province, Key Laboratory of Medicinal Chemistry and Molecular Diagnosis, Ministry of Education Hebei University, Baoding 071002, P. R. China
| | - Chunfang Zhang
- College of Chemistry and Environmental Science, Key Laboratory of Chemical Biology of Hebei Province, Key Laboratory of Medicinal Chemistry and Molecular Diagnosis, Ministry of Education Hebei University, Baoding 071002, P. R. China
| | - Jinchong Xiao
- College of Chemistry and Environmental Science, Key Laboratory of Chemical Biology of Hebei Province, Key Laboratory of Medicinal Chemistry and Molecular Diagnosis, Ministry of Education Hebei University, Baoding 071002, P. R. China
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Nishijima M, Mutoh K, Abe J. A Qualitative Measure of Diradical Character Based on Radical–Radical Coupling Reaction. CHEM LETT 2021. [DOI: 10.1246/cl.210267] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Moe Nishijima
- Department of Chemistry, Aoyama Gakuin University, Sagamihara, Kanagawa 252-5258, Japan
| | - Katsuya Mutoh
- Department of Chemistry, Aoyama Gakuin University, Sagamihara, Kanagawa 252-5258, Japan
| | - Jiro Abe
- Department of Chemistry, Aoyama Gakuin University, Sagamihara, Kanagawa 252-5258, Japan
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50
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Ueda H, Yoshimoto S. Multi-Redox Active Carbons and Hydrocarbons: Control of their Redox Properties and Potential Applications. CHEM REC 2021; 21:2411-2429. [PMID: 34128316 DOI: 10.1002/tcr.202100088] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2021] [Revised: 05/19/2021] [Indexed: 12/23/2022]
Abstract
Precise control over redox properties is essential for high-performance organic electronic devices such as organic batteries, electrochromic devices, and information storage devices. In this context, multi-redox active carbons and hydrocarbons, represented as Cx Hy molecules (x≥1, y≥0), are highly sought after, because they can switch between multiple redox states. Herein, we outline the redox properties of Cx Hy molecules as solutes and adsorbed species. Furthermore, the limitations of evaluating their redox properties and the possible solutions are summarized. Additionally, the theoretical capacity (mAh/g) and gravimetric energy density (Wh/kg) of secondary batteries were estimated based on the redox properties of 185 Cx Hy molecules, which have primarily been reported in the last decade. Among them, seven Cx Hy molecules were found to have the potential to surpass the energy density of LiNi0.6 Mn0.2 Co0.2 O2 /graphite batteries. The use of Cx Hy molecules in multielectrochromic devices and multi-bit memory is also explained. We believe that this review will encourage further utilization of Cx Hy molecules thereby promoting its applications in organic electronic devices.
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Affiliation(s)
- Hiroyuki Ueda
- Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Chuo-ku, Kumamoto, 860-8555, Japan
| | - Soichiro Yoshimoto
- Institute of Industrial Nanomaterials, Kumamoto University, 2-39-1 Kurokami, Chuo-ku, Kumamoto, 860-8555, Japan
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