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Investigation on the excited state intramolecular proton transfer process for the novel 2‐(3,5‐dichloro‐2‐hydroxy‐phenyl)‐benzooxazole‐5‐carboxylicacid system
Author(s) -
Gao Haiyan,
Yang Xiaohui,
Zhang Tianjie,
Yang Dapeng
Publication year - 2019
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.3989
Subject(s) - chemistry , excited state , intramolecular force , photoexcitation , hydrogen bond , intermolecular force , time dependent density functional theory , density functional theory , proton , quenching (fluorescence) , photochemistry , potential energy , hydrogen atom , chemical physics , computational chemistry , atomic physics , fluorescence , molecule , stereochemistry , physics , quantum mechanics , alkyl , organic chemistry
In view of the importance of excited state hydrogen bonding interactions and excited state proton transfer (ESPT) dynamical behaviors, in this work, we theoretically explore the excited state process for a novel 2‐(3,5‐dichloro‐2‐hydroxy‐phenyl)‐benzooxazole‐5‐carboxylicacid (DHPBC) system. On the basis of discrete Fourier transform (DFT) and time‐dependent density functional theory (TDDFT) methods, we reappear previous experimental reports with checking the reasonability of our theoretical level. We calculate and compare the primary geometrical parameters and hydrogen bonding energies around hydrogen bonding moieties, which reveals that the intramolecular hydrogen bond OH···N of DHPBC is enhanced in the S 1 state. The increased electron densities around N atom contribute to attracting proton of hydroxyl upon the photoexcitation, which plays important roles in strengthening hydrogen bond and in facilitating excited state intra‐ or intermolecular proton transfer (ESIPT) process. Via constructing potential energy curves along with the ESIPT path, we verify that the ESIPT process of DHPBC system is ultrafast because of the low potential energy barrier. That should be the reason why the normal emission of DHPBC cannot be detected in previous experiment. This work not only clarifies the excited state hydrogen bonding interactions and fills the vacancy of specific ESIPT mechanism for DHPBC system in experiment, but also explains the fluorescence quenching phenomenon.