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The ESIPT mechanism of dibenzimidazolo diimine sensor: a detailed TDDFT study
Author(s) -
Yang Dapeng,
Zheng Rui,
Wang Yusheng,
Lv Jian
Publication year - 2016
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.3513
Subject(s) - time dependent density functional theory , chemistry , intramolecular force , hydrogen bond , excited state , density functional theory , photochemistry , quenching (fluorescence) , molecular orbital , proton , fluorescence , computational chemistry , atomic physics , molecule , stereochemistry , physics , organic chemistry , quantum mechanics
Spectroscopic investigations on excited state proton transfer of a new dibenzimidazolo diimine sensor (DDS) were reported by Goswami et al . recently. In our present work, based on the time‐dependent density functional theory (TDDFT), the excited‐state intramolecular proton transfer (ESIPT) mechanism of DDS is studied theoretically. Our calculated results reproduced absorption and fluorescence emission spectra of the previous experiment, which verifies that the TDDFT method we adopted is reasonable and effective. The calculated dominating bond lengths and bond angles involved in hydrogen bond demonstrate that the intramolecular hydrogen bond is strengthened. In addition, the phenomenon of hydrogen bond reinforce has also been testified based on infrared vibrational spectra. Further, hydrogen bonding strengthening manifests the tendency of ESIPT process. The calculated frontier molecular orbitals further demonstrate that the excited state proton transfer is likely to occur. According to the calculated results of potential energy curves along O–H coordinate, the potential energy barrier of about 5.02 kcal/mol is discovered in the S 0 state. However, a lower potential energy barrier of 0.195 kcal/mol is found in the S 1 state, which demonstrates that the proton transfer process is more likely to happen in the S 1 state than the S 0 state. In other words, the proton transfer reaction can be facilitated based on the photo‐excitation effectively. Moreover, the phenomenon of fluorescence quenching could be explained based on the ESIPT mechanism. Copyright © 2015 John Wiley & Sons, Ltd.