1
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Emenike BU, Shinn DW, Spinelle RA, Yoo B, Rosario AM. Quantifying macrocyclization-induced strain utilizing N-phenylimides as conformational reporters. Chem Commun (Camb) 2024; 60:4040-4043. [PMID: 38421220 DOI: 10.1039/d3cc06296a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/02/2024]
Abstract
Incorporating an N-phenylimide unit into macrocycles enabled measurements of macrocyclization strains by comparing the N-phenylimide's conformational changes to similar units attached to a linear-chain control. Systems of larger macrocycles displayed negligible macrocyclization strain, while smaller macrocycles demonstrated proportionate effects, emphasizing the use of N-phenylimides as conformational reporters of macrocyclization strain.
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Affiliation(s)
- Bright U Emenike
- Department of Chemistry & Physics, State University of New York, 223 Store Hill Road, Old Westbury, NY 11568, USA.
| | - David W Shinn
- Chemistry Department, United States Merchant Academy, 300 Steamboat Road Kings Point, NY 11024, USA
| | - Ronald A Spinelle
- Department of Chemistry & Physics, State University of New York, 223 Store Hill Road, Old Westbury, NY 11568, USA.
| | - Barney Yoo
- Department of Chemistry, Hunter College, City University of New York, NY 10065, USA
| | - Ambar M Rosario
- Department of Chemistry & Physics, State University of New York, 223 Store Hill Road, Old Westbury, NY 11568, USA.
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2
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Liu Q, Onishi K, Miyazawa Y, Wang Z, Hatano S, Abe M. Energetically More Stable Singlet Cyclopentane-1,3-diyl Diradical with π-Single Bonding Character than the Corresponding σ-Single Bonded Compound. J Am Chem Soc 2023. [PMID: 37967336 DOI: 10.1021/jacs.3c10971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2023]
Abstract
Carbon-carbon σ-single bonds are crucial for constructing molecules like ethane derivatives (R3C-CR3), which are composed of tetrahedral four-coordinate carbons. Molecular functions, such as light absorption or emission, originate from the π-bonds existing in ethylene derivatives (R2C═CR2). In this study, a relatively stable cyclopentane-1,3-diyl species with π-single bonding system (C-π-C) with planar four-coordinate carbons is constructed. This diradicaloid is energetically more stable than the corresponding σ-single bonding system. The π-electron single bonding system provides deeper insights into the chemical bonding and the physical properties derived from the small energy gaps between the bonding and antibonding molecular orbitals.
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Affiliation(s)
- Qian Liu
- Department of Chemistry, Graduate School of Advanced Science and Engineering, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Hiroshima, Japan
| | - Keita Onishi
- Department of Chemistry, Graduate School of Advanced Science and Engineering, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Hiroshima, Japan
| | - Yuki Miyazawa
- Department of Chemistry, Graduate School of Advanced Science and Engineering, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Hiroshima, Japan
| | - Zhe Wang
- Department of Chemistry, Graduate School of Advanced Science and Engineering, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Hiroshima, Japan
| | - Sayaka Hatano
- Department of Chemistry, Graduate School of Advanced Science and Engineering, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Hiroshima, Japan
| | - Manabu Abe
- Department of Chemistry, Graduate School of Advanced Science and Engineering, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Hiroshima, Japan
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3
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Hou B, Li K, He H, Hu J, Xu Z, Xiang Q, Wang P, Chen X, Sun Z. Stable Crystalline Nanohoop Radical and Its Self-Association Promoted by van der Waals Interactions. Angew Chem Int Ed Engl 2023; 62:e202301046. [PMID: 36754831 DOI: 10.1002/anie.202301046] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 02/07/2023] [Accepted: 02/08/2023] [Indexed: 02/10/2023]
Abstract
A stable nanohoop radical (OR3) combining the structures of cycloparaphenylene and an olympicenyl radical is synthesized and isolated in the crystalline state. X-ray crystallographic analysis reveals that OR3 forms a unique head-to-tail dimer that further aggregates into a one-dimensional chain in the solid state. Variable-temperature NMR and concentration-dependent absorption measurements indicate that the π-dimer is not formed in solution. An energy decomposition analysis indicates that van der Waals interactions are the driving force for the self-association process, in contrast with other olympicenyl derivatives that favor π-dimerization. The physical properties in solution phase have been studied, and the stable cationic species obtained by one-electron chemical oxidation. This study offers a new molecular design to modulate the self-association of organic radicals for overcoming the spin-Peierls transition, and to prepare novel nanohoop compounds with spin-related properties.
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Affiliation(s)
- Bingxia Hou
- Institute of Molecular Plus, Department of Chemistry and Haihe Laboratory of Sustainable Chemical Transformations, Tianjin university, 92 Weijin Road, Tianjin, 300072, China
| | - Ke Li
- Institute of Molecular Plus, Department of Chemistry and Haihe Laboratory of Sustainable Chemical Transformations, Tianjin university, 92 Weijin Road, Tianjin, 300072, China
| | - Huijie He
- Institute of Molecular Plus, Department of Chemistry and Haihe Laboratory of Sustainable Chemical Transformations, Tianjin university, 92 Weijin Road, Tianjin, 300072, China
| | - Jinlian Hu
- Institute of Molecular Plus, Department of Chemistry and Haihe Laboratory of Sustainable Chemical Transformations, Tianjin university, 92 Weijin Road, Tianjin, 300072, China
| | - Zhuofan Xu
- Institute of Molecular Plus, Department of Chemistry and Haihe Laboratory of Sustainable Chemical Transformations, Tianjin university, 92 Weijin Road, Tianjin, 300072, China
| | - Qin Xiang
- Institute of Molecular Plus, Department of Chemistry and Haihe Laboratory of Sustainable Chemical Transformations, Tianjin university, 92 Weijin Road, Tianjin, 300072, China
| | - Peng Wang
- Institute of Molecular Plus, Department of Chemistry and Haihe Laboratory of Sustainable Chemical Transformations, Tianjin university, 92 Weijin Road, Tianjin, 300072, China
| | - Xing Chen
- Institute of Molecular Plus, Department of Chemistry and Haihe Laboratory of Sustainable Chemical Transformations, Tianjin university, 92 Weijin Road, Tianjin, 300072, China
| | - Zhe Sun
- Institute of Molecular Plus, Department of Chemistry and Haihe Laboratory of Sustainable Chemical Transformations, Tianjin university, 92 Weijin Road, Tianjin, 300072, China
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4
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Kasemthaveechok S, Abella L, Crassous J, Autschbach J, Favereau L. Organic radicals with inversion of SOMO and HOMO energies and potential applications in optoelectronics. Chem Sci 2022; 13:9833-9847. [PMID: 36128246 PMCID: PMC9430691 DOI: 10.1039/d2sc02480b] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Accepted: 07/06/2022] [Indexed: 11/21/2022] Open
Abstract
Organic radicals possessing an electronic configuration in which the energy of the singly occupied molecular orbital (SOMO) is below the highest doubly occupied molecular orbital (HOMO) level have recently attracted significant interest, both theoretically and experimentally. The peculiar orbital energetics of these SOMO-HOMO inversion (SHI) organic radicals set their electronic properties apart from the more common situation where the SOMO is the highest occupied orbital of the system. This review gives a general perspective on SHI, with key fundamental aspects regarding the electronic and structural factors that govern this particular electronic configuration in organic radicals. Selected examples of reported compounds with SHI are highlighted to establish molecular guidelines for designing this type of radical, and to showcase the potential of SHI radicals in organic spintronics as well as for the development of more stable luminescent radicals for OLED applications.
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Affiliation(s)
| | - Laura Abella
- Department of Chemistry, University at Buffalo, State University of New York Buffalo New York 14260 USA
| | | | - Jochen Autschbach
- Department of Chemistry, University at Buffalo, State University of New York Buffalo New York 14260 USA
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5
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Hou P, Peschtrich S, Huber N, Feuerstein W, Bihlmeier A, Krummenacher I, Schoch R, Klopper W, Breher F, Paradies J. Impact of Heterocycle Annulation on NIR Absorbance in Quinoid Thioacene Derivatives. Chemistry 2022; 28:e202200478. [PMID: 35254693 PMCID: PMC9314731 DOI: 10.1002/chem.202200478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Indexed: 11/30/2022]
Abstract
The synthesis and characterisation of a homologous series of quinoid sulfur‐containing imidazolyl‐substituted heteroacenes is described. The optoelectronic and magnetic properties were investigated by UV/vis, fluorescence and EPR spectroscopy as well as quantum‐chemical calculations, and were compared to those of the corresponding benzo congener. The room‐temperature and atmospherically stable quinoids display strong absorption in the NIR region between 678 and 819 nm. The dithieno[3,2‐b:2′,3′‐d]thiophene and the thieno[2′,3′:4,5]thieno[3,2‐b]thieno[2,3‐d]thiophene derivatives were EPR active at room temperature. For the latter, variable‐temperature EPR spectroscopy revealed the presence of a thermally accessible triplet state, with a singlet‐triplet separation of 14.1 kJ mol−1.
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Affiliation(s)
- Peng Hou
- Chemistry Department Paderborn University Warburger Straße 100 33098 Paderborn Germany
| | - Sebastian Peschtrich
- Chemistry Department Paderborn University Warburger Straße 100 33098 Paderborn Germany
| | - Nils Huber
- Institute of Physical Chemistry Karlsruhe Institute of Technology (KIT) Kaiserstraße 12 76131 Karlsruhe Germany
| | - Wolfram Feuerstein
- Institute of Inorganic Chemistry Karlsruhe Institute of Technology (KIT) Engesserstraße 15 76131 Karlsruhe Germany
| | - Angela Bihlmeier
- Institute of Physical Chemistry Karlsruhe Institute of Technology (KIT) Kaiserstraße 12 76131 Karlsruhe Germany
| | - Ivo Krummenacher
- Institute of Inorganic Chemistry University of Würzburg Am Hubland 97074 Würzburg Germany
| | - Roland Schoch
- Chemistry Department Paderborn University Warburger Straße 100 33098 Paderborn Germany
| | - Wim Klopper
- Institute of Physical Chemistry Karlsruhe Institute of Technology (KIT) Kaiserstraße 12 76131 Karlsruhe Germany
| | - Frank Breher
- Institute of Inorganic Chemistry Karlsruhe Institute of Technology (KIT) Engesserstraße 15 76131 Karlsruhe Germany
| | - Jan Paradies
- Chemistry Department Paderborn University Warburger Straße 100 33098 Paderborn Germany
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6
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Liu Q, Wang Z, Abe M. Impacts of Solvent and Alkyl Chain Length on the Lifetime of Singlet Cyclopentane-1,3-diyl Diradicaloids with π-Single Bonding. J Org Chem 2022; 87:1858-1866. [PMID: 35001629 DOI: 10.1021/acs.joc.1c02895] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The singlet 2,2-dialkoxycyclopentane-1,3-diyl diradicaloids are not only the important key intermediates in the process of bond homolysis but are also attracting attention as π-single bonding compounds. In the present study, the effects of solvent viscosity η (0.24-125.4 mPa s) and polarity π* (-0.11 to 1.00 kcal mol-1) on the reactivity of localized singlet diradicaloids were thoroughly investigated using 18 different solvents including binary mixed solvent systems containing ionic liquids. In low-η solvents (η < 1 mPa s), the lifetimes of singlet diradicaloids, which are determined by the rate constant for the isomerization of π-single-bonded singlet diradicaloids to the σ-bonded isomer, were substantially dependent on π*. Slower isomerization was observed in more polar solvents. In high-η solvents (η > 2 mPa s), the rate of isomerization was largely influenced by η in addition to π*. Slower isomerization was observed in more viscous solvents. Experimental results demonstrated the crucial roles of both solvent polarity and viscosity in the reactivity of singlet diradicaloids and thus clarified the characters of singlet diradicaloids and molecular motions during the chemical transformation. The dynamic solvent effect was further proved by a long alkyl chain introduced at a remote position of the reaction site.
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Affiliation(s)
- Qian Liu
- Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Zhe Wang
- Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Manabu Abe
- Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
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7
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Wang Z, Yadav P, Abe M. Long-lived localised singlet diradicaloids with carbon-carbon π-single bonding (C-π-C). Chem Commun (Camb) 2021; 57:11301-11309. [PMID: 34633003 DOI: 10.1039/d1cc04581d] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Localised singlet cyclopentane-1,3-diyl diradicaloids have been considered promising candidates for constructing carbon-carbon π-single bonds (C-π-C). However, the high reactivity during formation of the σ-bond has limited a deeper investigation of its unique chemical properties. In this feature article, recent progress in kinetic stabilisation based on the "stretch effect" and the "solvent dynamic effect" induced by the macrocyclic system is summarised. Singlet diradicaloids S-DR4a/b and S-DR4d containing macrocyclic rings showed much longer lifetimes at 293 K (14 μs for S-DR4a and 156 μs for S-DR4b in benzene) compared to the parent singlet diradicaloid S-DR2 having no macrocyclic ring (209 ns in benzene). Furthermore, the dynamic solvent effect in viscous solvents was observed for the first time in intramolecular σ-bond formation, the lifetime of S-DR4d increased to 400 μs in the viscous solvent glycerin triacetin at 293 K. The experimental results proved the validity of the "stretch effect" and the "solvent dynamic effect" on the kinetic stabilisation of singlet cyclopentane-1,3-diyl diradicaloids, and provided a strategy for isolating the carbon-carbon π-single bonded species (C-π-C), and towards a deeper understanding of the nature of chemical bonding.
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Affiliation(s)
- Zhe Wang
- Department of Chemistry, Graduate School of Advanced Science and Engineering, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan.
| | - Pinky Yadav
- Department of Chemistry, Graduate School of Advanced Science and Engineering, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan.
| | - Manabu Abe
- Department of Chemistry, Graduate School of Advanced Science and Engineering, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan.
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8
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Nukazawa T, Iwamoto T. π-Conjugated species with an unsupported Si-Si π-bond obtained from direct π-extension. Chem Commun (Camb) 2021; 57:9692-9695. [PMID: 34555142 DOI: 10.1039/d1cc04332c] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
1,3-Diethynylbicyclo[1.1.0]tetrasilanes that contain an unsupported bridgehead Si-Si π-bond and ethynyl π-moieties were synthesized by the reaction of a 1,3-dihalobicyclo[1.1.0]tetrasilane with the corresponding lithium acetylide. The substantial bathochromic shift of the longest-wavelength absorption band observed for the phenylethynyl-substituted bicyclo[1.1.0]tetrasilane in the solid state compared to that of the octynyl-substituted derivative suggested the presence of effective π-conjugation between the unsupported Si-Si π and ethynyl π units.
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Affiliation(s)
- Takumi Nukazawa
- Department of Chemistry, Graduate School of Science, Tohoku University, Aoba-ku, Sendai 980-8578, Japan.
| | - Takeaki Iwamoto
- Department of Chemistry, Graduate School of Science, Tohoku University, Aoba-ku, Sendai 980-8578, Japan.
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9
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Wang Z, Murata R, Abe M. SOMO-HOMO Conversion in Triplet Cyclopentane-1,3-diyl Diradicals. ACS OMEGA 2021; 6:22773-22779. [PMID: 34514248 PMCID: PMC8427779 DOI: 10.1021/acsomega.1c03125] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Accepted: 07/22/2021] [Indexed: 06/13/2023]
Abstract
According to the Aufbau principle, singly occupied molecular orbitals (SOMOs) are energetically higher lying than a highest doubly occupied molecular orbital (HOMO) in the electronically ground state of radicals. However, in the last decade, SOMO-HOMO-converted species have been reported in a limited group of radicals, such as distonic anion radicals and nitroxides. In this study, SOMO-HOMO conversion was observed in triplet 2,2-difluorocyclopentane-1,3-diyl diradicals DR3F1, DR4F1, and 2-fluorocyclopentante-1,3-diyl diradical DR3HF1, which contain the anthracyl unit at the remote position. The high HOMO energy in the anthracyl moiety and the low-lying SOMO-1 due to the fluoro-substituent effect are the key to the SOMO-HOMO conversion phenomenon. Furthermore, the cation radical DR3F1 + generated through the one-electron oxidation of DR3F1 was found to be a SOMO-HOMO-converted monoradical.
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Affiliation(s)
- Zhe Wang
- Department
of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Ryo Murata
- Department
of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Manabu Abe
- Department
of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
- Hiroshima
University Research Center for Photo-Drug-Delivery-System (HiU-P-DDS), Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
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10
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Sarkar SK, Abe M. Direct Detection of Singlet Cyclopentane-1,3-diyl Diradicals By Infrared and Ultraviolet-Visible Spectroscopy at Cryogenic Temperature and Their Photoreactivity. J Org Chem 2021; 86:12046-12053. [PMID: 34380315 DOI: 10.1021/acs.joc.1c01410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Photolysis of a 7,7-difluoro-1,4-diphenyl-2,3-diazabicyclo[2.2.1]hept-2-ene derivative (AZ1) using a 365 nm light-emitting diode in an Ar matrix at 4 K resulted in the formation of a planar singlet 2,2-difluoro-1,3-diphenylcyclopentane-1,3-diyl diradical derivative, S-DR1-pl (λmax = 520 nm). A singlet cyclopentane-1,3-diyl diradical system (S-DR1-pl) was directly detected by steady-state infrared (IR) spectroscopy. Due to the photolability of S-DR1-pl, initial photolysis of AZ1 also yielded the ring-closed product ret-CP1 and migration products trans-MG1 and/or cis-MG1, which were observed using IR spectra. Monitoring of prolonged photolysis using IR and ultraviolet-visible (UV-vis) spectra demonstrated the formation of the allylic cation CT1 (λmax = 470 nm). On the other hand, photolysis of a 7,7-dimethoxy-1,4-diphenyl-2,3-diazabicyclo[2.2.1]hept-2-ene derivative (AZ2) yielded a puckered conformer (instead of planar) of the corresponding diradical S-DR2-puc, which was detected by IR and UV-vis spectroscopy in an Ar matrix at 4 K. This spectroscopic characterization opens a new strategy to obtain more detailed information about the structure and reactivity of singlet cyclopentane-1,3-diyl diradicals.
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Affiliation(s)
- Sujan K Sarkar
- Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Manabu Abe
- Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan.,Hiroshima University Research Center for Photo-Drug-Delivery Systems (HiU-P-DDS), Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
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11
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Miyazawa Y, Wang Z, Matsumoto M, Hatano S, Antol I, Kayahara E, Yamago S, Abe M. 1,3-Diradicals Embedded in Curved Paraphenylene Units: Singlet versus Triplet State and In-Plane Aromaticity. J Am Chem Soc 2021; 143:7426-7439. [PMID: 33900091 DOI: 10.1021/jacs.1c01329] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Curved π-conjugated molecules and open-shell structures have attracted much attention from the perspective of fundamental chemistry, as well as materials science. In this study, the chemistry of 1,3-diradicals (DRs) embedded in curved cycloparaphenylene (CPPs) structures, DR-(n+3)CPPs (n = 0-5), was investigated to understand the effects of the curvature and system size on the spin-spin interactions and singlet versus triplet state, as well as their unique characteristics such as in-plane aromaticity. A triplet ground state was predicted for the larger 1,3-diradicals, such as the seven- and eight-paraphenylene-unit-containing diradicals DR-7CPP (n = 4) and DR-8CPP (n = 5), by quantum chemical calculations. The smaller-sized diradicals DR-(n+3)CPPs (n = 0-3) were found to possess singlet ground states. Thus, the ground-state spin multiplicity is controlled by the size of the paraphenylene cycle. The size effect on the ground-state spin multiplicity was confirmed by the experimental generation of DR-6CPP in the photochemical denitrogenation of its azo-containing precursor (AZ-6CPP). Intriguingly, a unique type of in-plane aromaticity emerged in the smaller-sized singlet states such as S-DR-4CPP (n = 1), as proven by nucleus-independent chemical shift calculations (NICS) and an analysis of the anisotropy of the induced current density (ACID), which demonstrate that homoconjugation between the 1,3-diradical moiety arises because of the curved and distorted bonding system.
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Affiliation(s)
- Yuki Miyazawa
- Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Zhe Wang
- Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Misaki Matsumoto
- Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Sayaka Hatano
- Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Ivana Antol
- Laboratory for Physical Organic Chemistry, Division of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia
| | - Eiichi Kayahara
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Shigeru Yamago
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Manabu Abe
- Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
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12
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Akisaka R, Ohga Y, Abe M. Dynamic solvent effects in radical-radical coupling reactions: an almost bottleable localised singlet diradical. Phys Chem Chem Phys 2020; 22:27949-27954. [PMID: 33184617 DOI: 10.1039/d0cp05235c] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Localised singlet diradicals are key intermediates in bond homolysis, which plays a crucial role in chemical reactions. However, thorough experimental analyses of the reaction dynamics and chemical properties are generally difficult because bond formation is rapid, even under low-temperature matrix conditions. In this study, the effects of solvent and pressure on the lifetimes of long-lived singlet diradicals with bulky substituents were investigated. The solvent dynamic effect was revealed to provide control over the rate constant of radical-radical coupling reactions, and an almost bottleable singlet diradical with a lifetime of ∼2 s at 293 K was obtained.
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Affiliation(s)
- Rikuo Akisaka
- Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan.
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