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Dai Y, Rambaldi F, Negri F. Eclipsed and Twisted Excimers of Pyrene and 2-Azapyrene: How Nitrogen Substitution Impacts Excimer Emission. Molecules 2024; 29:507. [PMID: 38276585 PMCID: PMC11154402 DOI: 10.3390/molecules29020507] [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: 12/27/2023] [Revised: 01/13/2024] [Accepted: 01/17/2024] [Indexed: 01/27/2024] Open
Abstract
Due to their unique photophysical and electronic properties, pyrene and its analogues have been the subject of extensive research in recent decades. The propensity of pyrene and its derivatives to form excimers has found wide application in various fields. Nitrogen-substituted pyrene derivatives display similar photophysical properties, but for them, excimer emission has not been reported to date. Here, we use time-dependent density functional theory (TD-DFT) calculations to investigate the low-lying exciton states of dimers of pyrene and 2-azapyrene. The excimer equilibrium structures are determined and the contribution of charge transfer (CT) excitations and intermolecular interactions to the exciton states is disclosed using a diabatization procedure. The study reveals that the dimers formed by the two molecules have quite similar exciton-state patterns, in which the relevant CT contributions govern the formation of excimer states, along with the La/Lb state inversion. In contrast with pyrene, the dipole-dipole interactions in 2-azapyrene stabilize the dark eclipsed excimer structure and increase the barrier for conversion into a bright twisted excimer. It is suggested that these differences in the nitrogen-substituted derivative might influence the excimer emission properties.
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Affiliation(s)
- Yasi Dai
- Department of Chemistry “Giacomo Ciamician”, University of Bologna, 40126 Bologna, Italy; (Y.D.); (F.R.)
- Center for Chemical Catalysis—C3, Alma Mater Studiorum—Università di Bologna, Via Selmi 2, 40126 Bologna, Italy
| | - Filippo Rambaldi
- Department of Chemistry “Giacomo Ciamician”, University of Bologna, 40126 Bologna, Italy; (Y.D.); (F.R.)
| | - Fabrizia Negri
- Department of Chemistry “Giacomo Ciamician”, University of Bologna, 40126 Bologna, Italy; (Y.D.); (F.R.)
- Center for Chemical Catalysis—C3, Alma Mater Studiorum—Università di Bologna, Via Selmi 2, 40126 Bologna, Italy
- Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali (INSTM), Research Unit of Bologna, 40126 Bologna, Italy
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2
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Hancock AC, Goerigk L. Noncovalently bound excited-state dimers: a perspective on current time-dependent density functional theory approaches applied to aromatic excimer models. RSC Adv 2023; 13:35964-35984. [PMID: 38090083 PMCID: PMC10712016 DOI: 10.1039/d3ra07381e] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Accepted: 11/21/2023] [Indexed: 05/12/2024] Open
Abstract
Excimers are supramolecular systems whose binding strength is influenced by many factors that are ongoing challenges for computational methods, such as charge transfer, exciton coupling, and London dispersion interactions. Treating the various intricacies of excimer binding at an adequate level is expected to be particularly challenging for time-dependent Density Functional Theory (TD-DFT) methods. In addition to well-known limitations for some TD-DFT methods in the description of charge transfer or exciton coupling, the inherent London dispersion problem from ground-state DFT translates to TD-DFT. While techniques to appropriately treat dispersion in DFT are well-developed for electronic ground states, these dispersion corrections remain largely untested for excited states. Herein, we aim to shed light on current TD-DFT methods, including some of the newest developments. The binding of four model excimers is studied across nine density functionals with and without the application of additive dispersion corrections against a wave function reference of SCS-CC2/CBS(3,4) quality, which approximates select CCSDR(3)/CBS data adequately. To our knowledge, this is the first study that presents single-reference wave function dissociation curves at the complete basis set level for the assessed model systems. It is also the first time range-separated double-hybrid density functionals are applied to excimers. In fact, those functionals turn out to be the most promising for the description of excimer binding followed by global double hybrids. Range-separated and global hybrids-particularly with large fractions of Fock exchange-are outperformed by double hybrids and yield worse dissociation energies and inter-molecular equilibrium distances. The deviation between each assessed functional and reference increases with system size, most likely due to missing dispersion interactions. Additive dispersion corrections of the DFT-D3(BJ) and DFT-D4 types reduce the average errors for TD-DFT methods but do so inconsistently and therefore do not offer a black-box solution in their ground-state parametrised form. The lack of appropriate description of dispersion effects for TD-DFT methods is likely hindering the practical application of the herein identified more efficient methods. Dispersion corrections parametrised for excited states appear to be an important next step to improve the applicability of TD-DFT methods and we hope that our work assists with the future development of such corrections.
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Affiliation(s)
- Amy C Hancock
- School of Chemistry, The University of Melbourne Parkville Australia +61-(0)3-8344 6784
| | - Lars Goerigk
- School of Chemistry, The University of Melbourne Parkville Australia +61-(0)3-8344 6784
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3
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Nikul'shin PV, Fedunov RG, Kuibida LV, Maksimov AM, Glebov EM, Stass DV. Recombination of X-ray-Generated Radical Ion Pairs in Alkane Solution Assembles Optically Inaccessible Exciplexes from a Series of Perfluorinated para-Oligophenylenes with N, N-Dimethylaniline. Int J Mol Sci 2023; 24:ijms24087568. [PMID: 37108728 PMCID: PMC10142361 DOI: 10.3390/ijms24087568] [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: 03/26/2023] [Revised: 04/14/2023] [Accepted: 04/18/2023] [Indexed: 04/29/2023] Open
Abstract
We demonstrate that a series of perfluorinated para-oligophenylenes C6F5-(C6F4)n-C6F5 (n = 1-3) produce exciplexes with N,N-dimethylaniline (DMA) in degassed X-irradiated n-dodecane solutions. The optical characterization of the compounds shows that their short fluorescence lifetimes (ca. 1.2 ns) and UV-Vis absorption spectra, overlapping with the spectrum of DMA with molar absorption coefficients of 2.7-4.6 × 104 M-1cm-1, preclude the standard photochemical exciplex formation pathway via selective optical generation of the local excited state of the donor and its bulk quenching by the acceptor. However, under X-rays, the efficient assembly of such exciplexes proceeds via the recombination of radical ion pairs, which delivers the two partners close to each other and ensures a sufficient energy deposition. The exciplex emission is completely quenched by the equilibration of the solution with air, providing a lower bound of exciplex emission lifetime of ca. 200 ns. The recombination nature of the exciplexes is confirmed by the magnetic field sensitivity of the exciplex emission band inherited from the magnetic field sensitivity from the recombination of spin-correlated radical ion pairs. Exciplex formation in such systems is further supported by DFT calculations. These first exciplexes from fully fluorinated compounds show the largest known red shift of the exciplex emission from the local emission band, suggesting the potential of perfluoro compounds for optimizing optical emitters.
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Affiliation(s)
- Pavel V Nikul'shin
- A.V. Topchiev Institute of Petrochemical Synthesis, 119991 Moscow, Russia
| | - Roman G Fedunov
- V.V. Voevodsky Institute of Chemical Kinetics and Combustion, 630090 Novosibirsk, Russia
| | - Leonid V Kuibida
- V.V. Voevodsky Institute of Chemical Kinetics and Combustion, 630090 Novosibirsk, Russia
| | - Alexander M Maksimov
- N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry, 630090 Novosibirsk, Russia
| | - Evgeni M Glebov
- V.V. Voevodsky Institute of Chemical Kinetics and Combustion, 630090 Novosibirsk, Russia
- Department of Natural Sciences, Novosibirsk State University, 630090 Novosibirsk, Russia
| | - Dmitri V Stass
- V.V. Voevodsky Institute of Chemical Kinetics and Combustion, 630090 Novosibirsk, Russia
- International Tomography Center, 630090 Novosibirsk, Russia
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5
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Hancock AC, Goerigk L. Noncovalently bound excited-state dimers: a perspective on current time-dependent density functional theory approaches applied to aromatic excimer models. RSC Adv 2022; 12:13014-13034. [PMID: 35520129 PMCID: PMC9062889 DOI: 10.1039/d2ra01703b] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Accepted: 04/12/2022] [Indexed: 01/21/2023] Open
Abstract
Excimers are supramolecular systems whose binding strength is influenced by many factors that are ongoing challenges for computational methods, such as charge transfer, exciton coupling, and London dispersion interactions. Treating the various intricacies of excimer binding at an adequate level is expected to be particularly challenging for Time-Dependent Density Functional Theory (TD-DFT) methods. In addition to well-known limitations for some TD-DFT methods in the description of charge transfer or exciton coupling, the inherent London dispersion problem from ground-state DFT translates to TD-DFT. While techniques to appropriately treat dispersion in DFT are well-developed for electronic ground states, these dispersion corrections remain largely untested for excited states. Herein, we aim to shed light on current TD-DFT methods, including some of the newest developments. The binding of four model excimers is studied across nine density functionals with and without the application of additive dispersion corrections against a wave function reference of SCS-CC2/CBS(3,4) quality, which approximates select CCSDR(3)/CBS data adequately. To our knowledge, this is the first study that presents single-reference wave function dissociation curves at the complete basis set level for the assessed model systems. It is also the first time range-separated double-hybrid density functionals are applied to excimers. In fact, those functionals turn out to be the most promising for the description of excimer binding followed by global double hybrids. Range-separated and global hybrids-particularly with large fractions of Fock exchange-are outperformed by double hybrids and yield worse dissociation energies and inter-molecular equilibrium distances. The deviation between each assessed functional and reference increases with system size, most likely due to missing dispersion interactions. Additive dispersion corrections of the DFT-D3(BJ) and DFT-D4 types reduce the average errors for TD-DFT methods but do so inconsistently and therefore do not offer a black-box solution in their ground-state parametrised form. The lack of appropriate description of dispersion effects for TD-DFT methods is likely hindering the practical application of the herein identified more efficient methods. Dispersion corrections parametrised for excited states appear to be an important next step to improve the applicability of TD-DFT methods and we hope that our work assists with the future development of such corrections.
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Affiliation(s)
- Amy C Hancock
- School of Chemistry, The University of Melbourne Parkville Australia +61-3-8344-6784
| | - Lars Goerigk
- School of Chemistry, The University of Melbourne Parkville Australia +61-3-8344-6784
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6
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Appiarius Y, Gliese PJ, Segler SAW, Rusch P, Zhang J, Gates PJ, Pal R, Malaspina LA, Sugimoto K, Neudecker T, Bigall NC, Grabowsky S, Bakulin AA, Staubitz A. BN-Substitution in Dithienylpyrenes Prevents Excimer Formation in Solution and in the Solid State. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2022; 126:4563-4576. [PMID: 35299818 PMCID: PMC8919264 DOI: 10.1021/acs.jpcc.1c08812] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 12/20/2021] [Indexed: 06/14/2023]
Abstract
Boron-nitrogen substitutions in polycyclic aromatic hydrocarbons (PAHs) have a strong impact on the optical properties of the molecules due to a significantly more heterogeneous electron distribution. However, besides these single-molecule properties, the observed optical properties of PAHs critically depend on the degree of intermolecular interactions such as π-π-stacking, dipolar interactions, or the formation of dimers in the excited state. Pyrene is the most prominent example showing the latter as it exhibits a broadened and strongly bathochromically shifted emission band at high concentrations in solution compared to the respective monomers. In the solid state, the impact of intermolecular interactions is even higher as it determines the crystal packing crucially. In this work, a thiophene-flanked BN-pyrene (BNP) was synthesized and compared with its all-carbon analogue (CCP) in solution and in the solid state by means of crystallography, NMR spectroscopy, UV-vis spectroscopy, and photoluminescence (PL) spectroscopy. In solution, PL spectroscopy revealed the solvent-dependent presence of excimers of CCP at high concentrations. In contrast, no excimers were found in BNP. Clear differences were also observed in the single-crystal packing motifs. While CCP revealed overlapped pyrene planes with centroid distances in the range of classical π-stacking interactions, the BNP scaffolds were displaced and significantly more spatially separated.
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Affiliation(s)
- Yannik Appiarius
- Institute
for Analytical and Organic Chemistry, University
of Bremen, Leobener Straße 7, D-28359 Bremen, Germany
- MAPEX
Center for Materials and Processes, University
of Bremen, Bibliothekstraße
1, D-28359 Bremen, Germany
| | - Philipp J. Gliese
- Institute
for Analytical and Organic Chemistry, University
of Bremen, Leobener Straße 7, D-28359 Bremen, Germany
- MAPEX
Center for Materials and Processes, University
of Bremen, Bibliothekstraße
1, D-28359 Bremen, Germany
| | - Stephan A. W. Segler
- Institute
for Analytical and Organic Chemistry, University
of Bremen, Leobener Straße 7, D-28359 Bremen, Germany
- MAPEX
Center for Materials and Processes, University
of Bremen, Bibliothekstraße
1, D-28359 Bremen, Germany
| | - Pascal Rusch
- Institute
of Physical Chemistry and Electrochemistry, Leibniz University Hannover, Callinstraße 3a, D-30167 Hannover, Germany
- Cluster
of Excellence PhoenixD (Photonics, Optics, and Engineering—Innovation
Across Disciplines), Leibniz University
Hannover, D-30167 Hannover, Germany
| | - Jiangbin Zhang
- Cavendish
Laboratory, University of Cambridge, 19 J J Thomson Avenue, CB3 0HE Cambridge, U.K.
- College of
Advanced Interdisciplinary Studies, National
University of Defense Technology, 410073 Changsha, Hunan, China
| | - Paul J. Gates
- School
of Chemistry, University of Bristol, Cantock’s Close, BS8 1TS Bristol, U.K.
| | - Rumpa Pal
- Institute
of Inorganic Chemistry and Crystallography, University of Bremen, Leobener Straße 7, D-28359 Bremen, Germany
| | - Lorraine A. Malaspina
- Institute
of Inorganic Chemistry and Crystallography, University of Bremen, Leobener Straße 7, D-28359 Bremen, Germany
- Department
of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Kunihisa Sugimoto
- Japan Synchrotron
Radiation Research Institute (JASRI), 1-1-1, Kouto, Sayo-cho, Hyogo 679-5198, Japan
| | - Tim Neudecker
- MAPEX
Center for Materials and Processes, University
of Bremen, Bibliothekstraße
1, D-28359 Bremen, Germany
- Institute for Physical and Theoretical
Chemistry, University of Bremen, Leobener Straße 7, D-28359 Bremen, Germany
- Bremen Center for Computational Materials
Science, University of Bremen, Am Fallturm 1, D-28359 Bremen, Germany
| | - Nadja C. Bigall
- Institute
of Physical Chemistry and Electrochemistry, Leibniz University Hannover, Callinstraße 3a, D-30167 Hannover, Germany
- Cluster
of Excellence PhoenixD (Photonics, Optics, and Engineering—Innovation
Across Disciplines), Leibniz University
Hannover, D-30167 Hannover, Germany
| | - Simon Grabowsky
- Institute
of Inorganic Chemistry and Crystallography, University of Bremen, Leobener Straße 7, D-28359 Bremen, Germany
- Department
of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Artem A. Bakulin
- Cavendish
Laboratory, University of Cambridge, 19 J J Thomson Avenue, CB3 0HE Cambridge, U.K.
- Department of Chemistry, Imperial College
London, Imperial College Rd, SW7 2AZ London, U.K.
| | - Anne Staubitz
- Institute
for Analytical and Organic Chemistry, University
of Bremen, Leobener Straße 7, D-28359 Bremen, Germany
- MAPEX
Center for Materials and Processes, University
of Bremen, Bibliothekstraße
1, D-28359 Bremen, Germany
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Kim S, Ahn DS, Ahn M, Wee KR, Choi J, Ihee H. Charge transfer induced by electronic state mixing in a symmetric X-Y-X-type multi-chromophore system. Phys Chem Chem Phys 2020; 22:28440-28447. [PMID: 33305764 DOI: 10.1039/d0cp05132b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Charge transfer (CT) from electron donor (D) to acceptor (A) plays an important role in photoelectric or electrochemical devices and is a useful concept for a molecule with D and A well distinguishable. Here, we report our finding that even in a molecule with D and A not resolvable, CT can be induced by electronic state mixing (ESM) in a symmetric multi-chromophore system (MCS), namely 1,4-di(1-pyrenyl)benzene (Py-Benz-Py). Unlike Py and Py-Benz, Py-Benz-Py exhibits unique photophysical properties attributable to the reduction of the energy gap between two electronic states induced by ESM. The ESM for Py-Benz-Py is due to the extended π-conjugation owing to the further introduction of Py into Py-Benz, and consequently leads to the favorable intramolecular CT, followed by the planarization due to the twisting motion between Py and phenyl moieties. Time-resolved spectroscopic data demonstrate that the twisting process of the Py moiety in acetonitrile occurs with two unequal time constants, suggesting the localized CT state and the asynchronous twisting dynamics of two Py moieties unlike the delocalized CT state in nonpolar and low-polarity solvents leading to the synchronous twisting of two Py moieties. This means that the symmetry-breaking CT in MCSs can induce an asynchronous twisting motion. The results reported here support that a molecule without CT can be turned into another molecule with CT induced by ESM and demonstrate that the excited-state relaxation dynamics can be regulated through the ESM induced by introducing the substituents or changing the environmental factors such as solvent polarities.
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Affiliation(s)
- Siin Kim
- Department of Chemistry and KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea.
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