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Vaccaro PH, Xu Y. Virtual Issue on Chiroptical Spectroscopy. J Phys Chem A 2023; 127:7677-7681. [PMID: 37732338 DOI: 10.1021/acs.jpca.3c05566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/22/2023]
Affiliation(s)
- Patrick H Vaccaro
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - Yunjie Xu
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2
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2
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Freytag E, Kreimendahl L, Holzapfel M, Petersen J, Lackinger H, Stolte M, Würthner F, Mitric R, Lambert C. Chiroptical Properties of Planar Benzobisthiazole-Bridged Squaraine Dimers. J Org Chem 2023. [PMID: 37487529 DOI: 10.1021/acs.joc.3c00821] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/26/2023]
Abstract
Five chiral squaraine dimers were synthesized by fusing chiral indolenine semisquaraines with three different benzobisthiazole bridges. The thereby created squaraine dimers show a strong splitting of the lowest energy absorption bands caused by exciton coupling. The intensities of the two exciton transitions and the energetic splitting depend on the angle of the two squaraine moieties within the chromophore dimer. The electric circular dichroism spectra of the dimers show intense Cotton effects whose sign depends on the used squaraine chromophores. Sizable anisotropies gabs of up to 2.6 × 10-3 could be obtained. TD-DFT calculations were used to partition the rotational strength into the three Rosenfeld terms where the electric-magnetic coupling turned out to be the dominant contribution while the exciton chirality term is much smaller. This is because the chromophore dimers are essentially planar but the angle between the electric transition dipole moment of one squaraine and the magnetic transition dipole moment of the other squaraine strongly deviates from 90°, which makes the dot product between the two moment vectors and, thus, the rotational strength substantial.
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Affiliation(s)
- Emely Freytag
- Institut für Organische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Lasse Kreimendahl
- Institut für Physikalische und Theoretische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Marco Holzapfel
- Institut für Organische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Jens Petersen
- Institut für Physikalische und Theoretische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Heiko Lackinger
- Institut für Organische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Matthias Stolte
- Institut für Organische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
- Center for Nanosystems Chemistry, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Frank Würthner
- Institut für Organische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
- Center for Nanosystems Chemistry, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Roland Mitric
- Institut für Physikalische und Theoretische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Christoph Lambert
- Institut für Organische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
- Center for Nanosystems Chemistry, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
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3
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Monti M, Stener M, Coccia E. Electronic circular dichroism from real-time propagation in state space. J Chem Phys 2023; 158:084102. [PMID: 36859092 DOI: 10.1063/5.0136392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
In this paper, we propose to compute the electronic circular dichroism (ECD) spectra of chiral molecules using a real-time propagation of the time-dependent Schrödinger equation (TDSE) in the space of electronic field-free eigenstates, by coupling TDSE with a given treatment of the electronic structure of the target. The time-dependent induced magnetic moment is used to compute the ECD spectrum from an explicit electric perturbation. The full matrix representing the transition magnetic moment in the space of electronic states is generated from that among pairs of molecular orbitals. In the present work, we show the ECD spectra of methyloxirane, of several conformers of L-alanine, and of the Λ-Co(acac)3 complex, computed from a singly excited ansatz of time-dependent density functional theory eigenstates. The time-domain ECD spectra properly reproduce the frequency-domain ones obtained in the linear-response regime and quantitatively agree with the available experimental data. Moreover, the time-domain approach to ECD allows us to naturally go beyond the ground-state rotationally averaged ECD spectrum, which is the standard outcome of the linear-response theory, e.g., by computing the ECD spectra from electronic excited states.
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Affiliation(s)
- M Monti
- Dipartimento di Scienze Chimiche e Farmaceutiche, Università di Trieste, Via L. Giorgieri 1, 34127 Trieste, Italy
| | - M Stener
- Dipartimento di Scienze Chimiche e Farmaceutiche, Università di Trieste, Via L. Giorgieri 1, 34127 Trieste, Italy
| | - E Coccia
- Dipartimento di Scienze Chimiche e Farmaceutiche, Università di Trieste, Via L. Giorgieri 1, 34127 Trieste, Italy
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Sharma A, Athanasopoulos S, Li Y, Sanders SN, Kumarasamy E, Campos LM, Lakhwani G. Probing Through-Bond and Through-Space Interactions in Singlet Fission-Based Pentacene Dimers. J Phys Chem Lett 2022; 13:8978-8986. [PMID: 36149007 DOI: 10.1021/acs.jpclett.2c02061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Interchromophoric interactions such as Coulombic coupling and exchange interactions are crucial to the functional properties of numerous π-conjugated systems. Here, we use magnetic circular dichroism (MCD) spectroscopy to investigate interchromophoric interactions in singlet fission relevant pentacene dimers. Using a simple analytical model, we outline a general relationship between the geometry of pentacene dimers and their calculated MCD response. We analyze experimental MCD spectra of different covalently bridged pentacene dimers to reveal how the molecular structure of the "bridge" affects the magnitude of through-space Coulombic and through-bond exchange interactions in the system. Our results show that through-bond interactions are significant in dimers with conjugated molecules as bridging units and these interactions promote the overall electronic coupling in the system. Our generalized approach paves the way for the application of MCD in investigating interchromophoric interactions across a range of π-conjugated systems.
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Affiliation(s)
- Ashish Sharma
- ARC Centre of Excellence in Exciton Science, School of Chemistry, The University of Sydney, Sydney, New South Wales 2006, Australia
- Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Stavros Athanasopoulos
- Departamento de Física, Universidad Carlos III de Madrid, Avenida Universidad 30, Leganés, 28911 Madrid, Spain
| | - Yun Li
- ARC Centre of Excellence in Exciton Science, School of Chemistry, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Samuel N Sanders
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Elango Kumarasamy
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Luis M Campos
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Girish Lakhwani
- ARC Centre of Excellence in Exciton Science, School of Chemistry, The University of Sydney, Sydney, New South Wales 2006, Australia
- The University of Sydney Nano Institute, Sydney, New South Wales 2006, Australia
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Freytag E, Holzapfel M, Swain A, Bringmann G, Stolte M, Würthner F, Lambert C. Axially chiral indolenine derived chromophore dimers and their chiroptical absorption and emission properties. Chem Sci 2022; 13:12229-12238. [PMID: 36349102 PMCID: PMC9601394 DOI: 10.1039/d2sc04600h] [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: 08/17/2022] [Accepted: 10/05/2022] [Indexed: 11/23/2022] Open
Abstract
Yamamoto homocoupling of two chiral oxindoles led to the atropo-diastereoselective formation of an axially chiral oxindole dimer. This building block served as the starting material for the syntheses of axially chiral squaraine and merocyanine chromophore dimers. These dimers show pronounced chiroptical properties, this is, outstandingly high ECD signals (Δε up to ca. 1500 M−1 cm−1) as a couplet with positive Cotton effect for the P-configuration around the biaryl axis and a negative Cotton effect for the M-configuration. All investigated dimers also exhibit pronounced circularly polarised emission with anisotropy values of ca. 10−3 cgs. Time-dependent density functional calculations were used to analyse the three contributions (local one electron, electric–magnetic coupling, and exciton coupling) to the rotational strength applying the Rosenfeld equation to excitonically coupled chromophores. While the exciton coupling term proves to be the dominant one, the electric–magnetic coupling possesses the same sign and adds significantly to the total rotational strength owing to a favourable geometric arrangement of the two chromophores within the dimer. From an axially chiral oxindole, squaraine and merocyanine chromophore dimers with pronounced chiroptical properties were prepared.![]()
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Affiliation(s)
- Emely Freytag
- Institut für Organische Chemie, Universität Würzburg, Am Hubland, Würzburg 97074, Germany
| | - Marco Holzapfel
- Institut für Organische Chemie, Universität Würzburg, Am Hubland, Würzburg 97074, Germany
| | - Asim Swain
- Institut für Organische Chemie, Universität Würzburg, Am Hubland, Würzburg 97074, Germany
| | - Gerhard Bringmann
- Institut für Organische Chemie, Universität Würzburg, Am Hubland, Würzburg 97074, Germany
| | - Matthias Stolte
- Institut für Organische Chemie, Universität Würzburg, Am Hubland, Würzburg 97074, Germany
- Center for Nanosystems Chemistry, Universität Würzburg, Theodor-Boveri-Weg, Würzburg 97074, Germany
| | - Frank Würthner
- Institut für Organische Chemie, Universität Würzburg, Am Hubland, Würzburg 97074, Germany
- Center for Nanosystems Chemistry, Universität Würzburg, Theodor-Boveri-Weg, Würzburg 97074, Germany
| | - Christoph Lambert
- Institut für Organische Chemie, Universität Würzburg, Am Hubland, Würzburg 97074, Germany
- Center for Nanosystems Chemistry, Universität Würzburg, Theodor-Boveri-Weg, Würzburg 97074, Germany
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