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Kong J, Zhang W, Shao JY, Huo D, Niu X, Wan Y, Song D, Zhong YW, Xia A. Bridge-Length- and Solvent-Dependent Charge Separation and Recombination Processes in Donor-Bridge-Acceptor Molecules. J Phys Chem B 2021; 125:13279-13290. [PMID: 34814686 DOI: 10.1021/acs.jpcb.1c08308] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The photoinduced intramolecular charge separation (CS) and charge recombination (CR) phenomena in a series of donor-bridge-acceptor (D-B-A) molecules are intensively investigated as a means of understanding electron transport through the π-B. Pyrene (Pyr) and triarylamine (TAA) moieties connected via phenylene Bs of various lengths are studied because their CS and CR behaviors can be readily monitored in real time by femtosecond transient absorption (fs-TA) spectroscopy. By combining the steady-state and fs-TA spectroscopic measurements in a variety of solvents together with chemical calculations, the parameters that govern the CS behaviors of these dyads were obtained, such as the solvent effects on free energy and the B-length-dependent electronic coupling (VDA) between D and A. We observed the sharp switch of the CS behavior with the increase of the solvent polarity and B-linker lengths. Furthermore, in the case of the shortest distance between D and A when the electron coupling is sufficiently large, we observed that the CS phenomenon occurs even in low-polar solvents. Upon increasing the length of B, CS occurs only in strong polar solvents. The distance-dependent decay constant of the CS rate is determined as ∼0.53 Å-1, indicating that CS is governed by superexchange tunneling interactions. The CS rate constants are also approximately estimated using Marcus electron transfer theory, and the results imply that the VDA value is the key factor dominating the CS rate, while the facile rotation of the phenylene B is important for modulating the lifetime of the charge-separated state in these D-B-A dyads. These results shed light on the practical strategy for obtaining a high CS efficiency with a long-lived CS state in TAA-B-Pyr derivatives.
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Affiliation(s)
- Jie Kong
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China.,University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Wei Zhang
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China.,University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Jiang-Yang Shao
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Dayujia Huo
- College of Chemistry, Beijing Normal University, Beijing 100875, P. R. China
| | - Xinmiao Niu
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China.,University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Yan Wan
- College of Chemistry, Beijing Normal University, Beijing 100875, P. R. China
| | - Di Song
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China.,School of Science, Beijing University of Posts and Telecommunications (BUPT), Beijing 100876, People's Republic of China
| | - Yu-Wu Zhong
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China.,University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Andong Xia
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China.,School of Science, Beijing University of Posts and Telecommunications (BUPT), Beijing 100876, People's Republic of China
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Taha MA, Dappour AM, Ismail MA, Kamel AH, Abdel-Shafi AA. Solvent polarity indicators based on bithiophene carboxamidine hydrochloride salt derivatives. J Photochem Photobiol A Chem 2021. [DOI: 10.1016/j.jphotochem.2020.112933] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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