1
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Mizuno Y, Nogata A, Suzuki M, Nakayama KI, Hisaki I, Kishi R, Konishi A, Yasuda M. Synthesis and Characterization of Dibenzothieno[ a, f]pentalenes Enabling Large Antiaromaticity and Moderate Open-Shell Character through a Small Energy Barrier for Bond-Shift Valence Tautomerization. J Am Chem Soc 2023; 145:20595-20609. [PMID: 37695346 DOI: 10.1021/jacs.3c07356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
Experimental and theoretical rationalization of bond-shift valence tautomerization, characterized by double-well potential surfaces, is one of the most challenging topics of study among the rich electronic properties of antiaromatic molecules. Although the pseudo-Jahn-Teller effect (PJTE) is an essential effect to provide attractive characteristics of 4nπ systems, an understanding of the structure-property relationship derived from the PJTE for planar 4nπ electron systems is still in its infancy. Herein, we describe the synthesis and characterization of two regioisomers of the thiophene-fused diareno[a,f]pentalenes 6 and 7. The magnetic and optoelectronic properties characterize these sulfur-doped diareno[a,f]pentalenes as open-shell antiaromatic molecules, in sharp contrast to the closed-shell antiaromatic systems of 3 and 5, in which these main cores consist of the same number of π electrons as 6 and 7. Notably, thiophene-fused 6b and 7b showed pronounced antiaromaticity, the strongest among the previous systems, as well as moderate open-shell characteristics. Our experimental and theoretical investigations concluded that these properties of 6b and 7b are derived from the small energy barrier Ea‡ for the bond-shift valence tautomerization. The energy profile of the single crystal of 6b showed the temperature-dependent structural variations assigned to the dynamic mutual exchange between the two Cs-symmetric structures, which was also supported by changes in the chemical shifts of variable-temperature 1H NMR spectra in the solution phase. Both experimental and computational results revealed the importance of introducing heteroaromatic rings into 4nπ systems for controlling the PJTE and manifesting the antiaromatic and open-shell natures originating from the high-symmetric structure. The findings of this study advance the understanding of antiaromaticity characterized by the PJTE by controlling the energy barrier for bond-shift valence tautomerizations, potentially leading to the rational design of optoelectronic devices based on novel antiaromatic molecules possessing the strong contributions of their high-symmetric geometries.
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Affiliation(s)
- Yusuke Mizuno
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Akira Nogata
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Mitsuharu Suzuki
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Ken-Ichi Nakayama
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Ichiro Hisaki
- Division of Chemistry, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan
| | - Ryohei Kishi
- Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan
- Center for Quantum Information and Quantum Biology (QIQB), Osaka University, Toyonaka, Osaka 560-8531, Japan
- Innovative Catalysis Science Division, Institute for Open and Transdisciplinary Research Initiatives (ICS-OTRI), Osaka University, Suita, Osaka 565-0871, Japan
| | - Akihito Konishi
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
- Innovative Catalysis Science Division, Institute for Open and Transdisciplinary Research Initiatives (ICS-OTRI), Osaka University, Suita, Osaka 565-0871, Japan
| | - Makoto Yasuda
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, 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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2
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Zhang Y, Li W, Jiang R, Zhang L, Li Y, Xu X, Liu X. Synthetic Doping of Acenaphthylene through BN/CC Isosterism and a Direct Comparison with BN-Acenaphthene. J Org Chem 2022; 87:12986-12996. [PMID: 36149831 DOI: 10.1021/acs.joc.2c01534] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Boron/nitrogen-doped acenaphthylenes, a new class of BN-doped cyclopenta-fused polycyclic aromatic hydrocarbons, were synthesized via indole-directed C-H borylation. The reference molecule BN-acenaphthene was also synthesized in a similar manner. Both BN-acenaphthylene and BN-acenaphthene were unequivocally characterized by single-crystal X-ray analysis. The aromaticities of each ring in BN-acenaphthylenes were quantified by experimental and theoretical methods. Moreover, doping the BN unit into acenaphthylene can increase the LUMO level and decrease the HOMO level, resulting in wider HOMO-LUMO energy gaps. Furthermore, regioselective bromination of BN-acenaphthylene (B-Mes) afforded monobrominated BN-acenaphthylene in good yield. Subsequently, cross-coupling of brominated BN-acenaphthylene gave a series of BN-acenaphthylene derivatives. In addition, the photophysical properties of these BN-acenaphthylene derivatives can be fine-tuned by the substituents on the BN-acenaphthylene scaffold.
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Affiliation(s)
- Yanli Zhang
- School of Chemistry and Chemical Engineering, Tianjin University of Technology, Tianjin 300384, People's Republic of China
| | - Wenlong Li
- School of Chemistry and Chemical Engineering, Tianjin University of Technology, Tianjin 300384, People's Republic of China
| | - Ruijun Jiang
- School of Chemistry and Chemical Engineering, Tianjin University of Technology, Tianjin 300384, People's Republic of China
| | - Lei Zhang
- School of Science, Tianjin Chengjian University, Tianjin 300384, People's Republic of China
| | - Yuanhao Li
- School of Chemistry and Chemical Engineering, Tianjin University of Technology, Tianjin 300384, People's Republic of China
| | - Xiaoyang Xu
- School of Chemistry and Chemical Engineering, Tianjin University of Technology, Tianjin 300384, People's Republic of China
| | - Xuguang Liu
- School of Chemistry and Chemical Engineering, Tianjin University of Technology, Tianjin 300384, People's Republic of China.,State Key Laboratory of Elemento-Organic Chemistry, Nankai University, Tianjin 300071, People's Republic of China
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3
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Li E, Jin M, Jiang R, Zhang L, Zhang Y, Liu M, Wu X, Liu X. Synthesis, Characterization, and Properties of BN-Fluoranthenes. Org Lett 2022; 24:5503-5508. [PMID: 35730794 DOI: 10.1021/acs.orglett.2c01342] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Boron/nitrogen-doped fluoranthenes, a new class of BN-doped cyclopenta-fused polycyclic aromatic hydrocarbons, were synthesized via pyrrolic-type nitrogen directed C-H borylation. Regioselective bromination of BN-fluoranthene (3a) gave mono- and dibrominated BN-fluoranthenes. The halogenated BN-fluoranthene (3b) can undergo various of further cross-coupling reactions to deliver a series of BN-fluoranthenes. Moreover, incorporating BN unit in to fluoranthene resulted in a wider HOMO-LUMO energy gaps. The aromaticities of the BN-fluoranthene (3a) were quantified by experimental and computational studies.
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Affiliation(s)
- Erlong Li
- School of Chemistry and Chemical Engineering, Tianjin University of Technology, Tianjin 300384, People's Republic of China
| | - Mengjia Jin
- School of Materials Science and Engineering, Tianjin University of Technology, Tianjin 300384, People's Republic of China
| | - Ruijun Jiang
- School of Chemistry and Chemical Engineering, Tianjin University of Technology, Tianjin 300384, People's Republic of China
| | - Lei Zhang
- School of Science, Tianjin Chengjian University, Tianjin 300384, People's Republic of China
| | - Yanli Zhang
- School of Chemistry and Chemical Engineering, Tianjin University of Technology, Tianjin 300384, People's Republic of China
| | - Meiyan Liu
- School of Chemistry and Chemical Engineering, Tianjin University of Technology, Tianjin 300384, People's Republic of China
| | - Xiaoming Wu
- School of Materials Science and Engineering, Tianjin University of Technology, Tianjin 300384, People's Republic of China
| | - Xuguang Liu
- School of Chemistry and Chemical Engineering, Tianjin University of Technology, Tianjin 300384, People's Republic of China.,State Key Laboratory of Elemento-Organic Chemistry, Nankai University, Tianjin 300071, People's Republic of China
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4
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Baranac-Stojanović M, Stojanović M, Aleksić J. Revival of Hückel Aromatic (Poly)benzenoid Subunits in Triplet State Polycyclic Aromatic Hydrocarbons by Silicon Substitution. Chem Asian J 2021; 17:e202101261. [PMID: 34964285 DOI: 10.1002/asia.202101261] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 12/22/2021] [Indexed: 11/08/2022]
Abstract
By employing density functional theory (DFT) calculations we show that mono- and disilicon substitution in polycyclic aromatic hydrocarbons, having two to four benzene units, quenches their triplet state antiaromaticity by creating Hückel aromatic (poly)benzenoid subunit(s) and weakly antiaromatic, or almost nonaromatic silacycle. Therefore, such systems are predicted to be globally aromatic in both the ground state and the first excited triplet state. Putting the silicon atom(s) into various positions of a hydrocarbon provides an opportunity to tune the singlet-triplet energy gaps. They depend on the global aromaticity degree which, in turn, depends on the type of aromatic carbocyclic subunit(s) and the extent of their aromaticity. On the basis of the set of studied compounds, some preliminary rules on how to regulate the extent of global, semiglobal and local aromaticity are proposed. The results of this work extend the importance of Hückel aromaticity concept to excited triplet states which are usually characterized by the Baird type of (anti)aromaticity.
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Affiliation(s)
- Marija Baranac-Stojanović
- Faculty of Chemistry, University of Belgrade, Organic Chemistry, Studentski trg 16, 11000, Belgrade, SERBIA
| | - Milovan Stojanović
- Institute of Chemistry Technology and Metallurgy: Institut za hemiju tehnologiju i metalurgiju, Center for Chemistry, SERBIA
| | - Jovana Aleksić
- Institute of Chemistry Technology and Metallurgy: Institut za hemiju tehnologiju i metalurgiju, Center for Chemistry, SERBIA
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5
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Xu T, Han Y, Shen Z, Hou X, Jiang Q, Zeng W, Ng PW, Chi C. Antiaromatic Dicyclopenta[ b,g]/[ a,f]naphthalene Isomers Showing an Open-Shell Singlet Ground State with Tunable Diradical Character. J Am Chem Soc 2021; 143:20562-20568. [PMID: 34843229 DOI: 10.1021/jacs.1c06677] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Since the first isolation of 1,3,5,7-tetra-tert-butyl-s-indacene in 1986, core-expanded s- and as-indacenes have attracted intensive interest. However, there is no reported synthesis of such type of molecules due to their high reactivity for over 30 years. Herein, we report the successful synthesis of two relatively stable, core-expanded indacene isomers, dicyclopenta[b,g]-naphthalene (5) and dicyclopenta[a,f]naphthalene (6). X-ray crystallographic analyses reveal that the backbone of 5 adopts a bond-delocalized structure, while that of 6 exhibits a bond-localized character. Variable-temperature 1H NMR/ESR measurements, electronic absorption spectra, and theoretical calculations confirm that both molecules are globally antiaromatic and have an open-shell singlet ground state. However, 6 shows stronger antiaromaticity, a larger diradical character (y0 = 48%), and a smaller singlet-triplet energy gap (ΔES-T = -0.99 kcal mol-1) compared to 5 (y0 = 30%, ΔES-T = -6.88 kcal mol-1), which can be explained by their different quinoidal structures.
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Affiliation(s)
- Tingting Xu
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543 Singapore, Singapore
| | - Yi Han
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543 Singapore, Singapore
| | - Zhongjin Shen
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543 Singapore, Singapore
| | - Xudong Hou
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543 Singapore, Singapore
| | - Qing Jiang
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543 Singapore, Singapore
| | - Wangdong Zeng
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543 Singapore, Singapore
| | - Pei Wen Ng
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543 Singapore, Singapore
| | - Chunyan Chi
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543 Singapore, Singapore
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6
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Mono- and Dinitro-BN-Naphthalenes: Formation and Characterization. Molecules 2021; 26:molecules26144209. [PMID: 34299484 PMCID: PMC8303104 DOI: 10.3390/molecules26144209] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 07/03/2021] [Accepted: 07/06/2021] [Indexed: 12/01/2022] Open
Abstract
Mono- and dinitro-BN-naphthalenes, i.e., 1-nitro-, 3-nitro-, 1,6-dinitro-, 3,6-dinitro-, and 1,8-dinitro-BNN, were generated in the nitration of 9,10-BN-naphthalene (BNN), a boron–nitrogen (BN) bond-embedded naphthalene, with AcONO2 and NO2BF4 in acetonitrile. The nitrated products were isolated and characterized by NMR, GC-MS, IR, and X-ray single crystallography. The effects of the nitration on the electron density and aromaticity of BNN were evaluated by B-11 NMR analysis and HOMA calculations.
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7
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Anjalikrishna PK, Gadre SR, Suresh CH. Antiaromaticity-Aromaticity Interplay in Fused Benzenoid Systems Using Molecular Electrostatic Potential Topology. J Phys Chem A 2021; 125:5999-6012. [PMID: 34210140 DOI: 10.1021/acs.jpca.1c04286] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The phenomenon of antiaromaticity-aromaticity interplay in aromatic-antiaromatic (A-aA)-fused systems is studied using molecular electrostatic potential (MESP) analysis, which clearly brings out the electron-rich π-regions of molecular systems. Benzene, naphthalene, phenanthrene, and pyrene are the aromatic units and cyclobutadiene and pentalene are the antiaromatic units considered to construct the A-aA-fused systems. The fused system is seen to reduce the antiaromaticity by adopting a configuration containing the least number of localized bonds over antiaromatic moieties. This is clearly observed in 25 isomers of a fused system composed of three naphthalene and two cyclobutadiene units. Denoting the number of π-bonds in the cyclobutadiene rings by the notation (n, n'), the systems belonging to the class (0, 0) and (2, 2) turn out to be the most and least stable configurations, respectively. The stability of the fused system depends on the empty π-character of the antiaromatic ring, hence naphthalene and benzene prefer to fuse with cyclobutadiene in a linear and angular fashion, respectively. Generally, a configuration with the maximum number of 'empty' rings (0, 0, 0, ...) is considered to be the most stable for the given A-aA system. The stability and aromatic/antiaromatic character of A-aA-fused systems with pentalene is also interpreted in a similar way. MESP topology, clearly bringing out the distribution of double bonds in the fused systems, leads to a simple interpretation of the aromatic/antiaromatic character of them. Also, it leads to powerful predictions on stable macrocyclic A-aA systems.
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Affiliation(s)
- Puthannur K Anjalikrishna
- Chemical Sciences and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology, Thiruvananthapuram, Kerala 695019, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Shridhar R Gadre
- Department of Scientific Computing, Modelling and Simulation, SavitribaiPhule Pune University, Pune 411007, India
| | - Cherumuttathu H Suresh
- Chemical Sciences and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology, Thiruvananthapuram, Kerala 695019, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
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8
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Konishi A, Horii K, Iwasa H, Okada Y, Kishi R, Nakano M, Yasuda M. Characterization of Benzo[a]naphtho[2,3-f]pentalene: Interrelation between Open-shell and Antiaromatic Characters Governed by Mode of the Quinoidal Subunit and Molecular Symmetry. Chem Asian J 2021; 16:1553-1561. [PMID: 33861497 DOI: 10.1002/asia.202100398] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Indexed: 12/18/2022]
Abstract
The singlet open-shell character and antiaromaticity are intriguing features in π-conjugated carbocycles. These two exhibit similar chemical and physical properties. However, they rarely coexist in the same molecule. Understanding the interrelation between the open-shell and antiaromatic characteristics in the same molecule is crucial to control the electronic properties. Herein we describe the synthesis and characterization of a new member of diareno[a,f]pentalene, benzo[a]naphtho[2,3-f]pentalene 6. Unlike its isomer 5 with a closed-shell ground state, 6 exhibits an appreciable open-shell character and a moderate antiaromatic feature. The behaviors of the open-shell index (y0 ) against the difference of the proton chemical signal (Δδ(H1 )) between pentalenide dianions/neutral pentalenes for our reported pentalenes 1, 4, 5, and 6 give a thought-provoking conclusion about the interrelation between open-shell and antiaromatic characteristics in this series. The mode of the incorporated quinoidal moiety and the formal molecular symmetry are critical to balance these two characteristics.
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Affiliation(s)
- Akihito Konishi
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan.,Center for Atomic and Molecular Technologies, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan.,Innovative Catalysis Science Division, Institute for Open and Transdisciplinary Research Initiatives (ICS-OTRI), Osaka University, Suita, Osaka, 565-0871, Japan
| | - Koki Horii
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Haruna Iwasa
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Yui Okada
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Ryohei Kishi
- Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan.,Center for Quantum Information and Quantum Biology, Institute for Open and Transdisciplinary Research Initiatives (QIQB-OTRI), Osaka University, Toyonaka, Osaka, 560-8531, Japan
| | - Masayoshi Nakano
- Innovative Catalysis Science Division, Institute for Open and Transdisciplinary Research Initiatives (ICS-OTRI), Osaka University, Suita, Osaka, 565-0871, Japan.,Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan.,Center for Quantum Information and Quantum Biology, Institute for Open and Transdisciplinary Research Initiatives (QIQB-OTRI), Osaka University, Toyonaka, Osaka, 560-8531, Japan.,Center for Spintronics Research Network (CSRN), Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, 560-8531, Japan
| | - Makoto Yasuda
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, 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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9
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Naskar S, Das M. Effects of low-lying excitations in pentalene and its derivatives in singlet fission: a model exact and density matrix renormalisation group study. Mol Phys 2021. [DOI: 10.1080/00268976.2021.1895346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Sumit Naskar
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, India
| | - Mousumi Das
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, India
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10
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Konishi A, Yasuda M. Synthesis and Characterization of π-Extended Nonalternant Hydrocarbons Containing Azulene, Pentalene, and Heptalene Frameworks. J SYN ORG CHEM JPN 2021. [DOI: 10.5059/yukigoseikyokaishi.79.224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Akihito Konishi
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University
| | - Makoto Yasuda
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University
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11
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Konishi A, Yasuda M. Breathing New Life into Nonalternant Hydrocarbon Chemistry: Syntheses and Properties of Polycyclic Hydrocarbons Containing Azulene, Pentalene, and Heptalene Frameworks. CHEM LETT 2021. [DOI: 10.1246/cl.200650] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Akihito Konishi
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
- Center for Atomic and Molecular Technologies, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Makoto Yasuda
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
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12
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Konishi A, Yasuda M. Synthesis of π-extended non-alternant hydrocarbons based on azulene (5-7), pentalene (5-5) and heptalene (7-7) skeletons and elucidation of their electronic structures. ADVANCES IN PHYSICAL ORGANIC CHEMISTRY 2021. [DOI: 10.1016/bs.apoc.2021.10.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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13
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Baranac-Stojanović M, Stojanović M, Aleksić J. Triplet state (anti)aromaticity of some monoheterocyclic analogues of benzene, naphthalene and anthracene. NEW J CHEM 2021. [DOI: 10.1039/d1nj00207d] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
By employing DFT calculations, we show the influence of heteroatom substitution on the triplet state (anti)aromaticity of benzene, naphthalene and anthracene.
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Affiliation(s)
| | - Milovan Stojanović
- University of Belgrade – Institute of Chemistry
- Technology and Metallurgy – Center for Chemistry
- Belgrade
- Serbia
| | - Jovana Aleksić
- University of Belgrade – Institute of Chemistry
- Technology and Metallurgy – Center for Chemistry
- Belgrade
- Serbia
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14
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Abstract
Density functional theory calculations have been performed to explore the substituent effect on benzene's structure and aromaticity upon excitation to the first triplet excited state (T1). Discussion is based on spin density analysis, HOMA (harmonic oscillator model of aromaticity), NICS (nucleus-independent chemical shift), ACID (anisotropy of the induced current density), and monohydrogenation free energies and shows that a large span of aromatic properties, from highly antiaromatic to strongly aromatic, could be achieved by varying the substituent. This opens up a possibility of controlling benzene's physicochemical behavior in its excited state, while molecular motion, predicted for several derivatives, could be of interest for the development of photomechanical materials.
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Affiliation(s)
- Marija Baranac-Stojanović
- Faculty of Chemistry, University of Belgrade, Studentski trg 12-16, P.O. Box 158, Belgrade 11000, Serbia
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15
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Baranac-Stojanović M. Triplet-State Structures, Energies, and Antiaromaticity of BN Analogues of Benzene and Their Benzo-Fused Derivatives. J Org Chem 2019; 84:13582-13594. [PMID: 31538474 DOI: 10.1021/acs.joc.9b01858] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
It is well known that benzene is aromatic in the ground state (the Hückel's rule) and antiaromatic in the first triplet (T1) excited state (the Baird's rule). Whereas its BN analogues, the three isomeric dihydro-azaborines, have been shown to have various degrees of aromaticity in their ground state, almost no data are available for their T1 states. Thus, the purpose of this work is to theoretically [B3LYP/6-311+G(d,p)] predict structures, energies, and antiaromaticity of T1 dihydro-azaborines and some benzo-fused derivatives. Conclusions are based on spin density analysis, isogyric and hydrogenation reactions, HOMA, NICS, and ACID calculations. The results suggest that singlet-triplet energy gaps, antiaromaticity, and related excited-state properties of benzene, naphthalene, and anthracene could be tuned and controlled by the BN substitution pattern. While all studied compounds remain (nearly) planar upon excitation, the spin density distribution in T1 1,4-dihydro-azaborine induces a conformational change by which the two co-planar C-H bonds in the ground state become perpendicular to each other in the excited state. This predicted change in geometry could be of interest for the design of new photomechanical materials. Excitation of B-CN/N-NH2 1,4-azaborine would have a few effects: intramolecular charge transfer, aromaticity reversal, rotation, and stereoelectronic Umpolung of the amino group.
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Affiliation(s)
- Marija Baranac-Stojanović
- Faculty of Chemistry , University of Belgrade , Studentski trg 12-16 , P.O.Box 158, 11000 Belgrade , Serbia
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