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Indexed by:期刊论文

Date of Publication:2018-07-21

Journal:NEW JOURNAL OF CHEMISTRY

Included Journals:SCIE

Volume:42

Issue:14

Page Number:11804-11810

ISSN No.:1144-0546

Abstract:The dual-luminescence mechanism of the tetrasubstituted imidazole core (TIC) compound was theoretically explored by considering the excited-state intramolecular proton transfer (ESIPT) process in the present study. Density functional theory (DFT) and time-dependent density functional theory (TDDFT) methods have been employed to gain the geometrical conformations, electronic transitions, frontier molecular orbitals (FMOs) and various spectra in different electronic states. An intramolecular hydrogen bond O-HN was observed for the TIC in the S-0 state. Upon electronic excitation, the TIC molecule is predominantly excited to the S-1 state as well as to an isosbestic point in the S-2 state. There is a twisted intramolecular charge transfer (TICT) during the S-0 S-1 (-*) transition and an intramolecular charge transfer (ICT) during the S-0 S-2 (-*) transition. The intramolecular hydrogen bond becomes stronger in the S-1 state than in the S-0 state. This leads to a strong fluorescence emission at 461 nm. However, the calculated potential curves showed that the intramolecular hydrogen bond O-HN transforms into OH-N in the S-2 state after the ESIPT reaction. A keto form of TIC is generated which gives rise to the other fluorescence emission at 575 nm through an ultrafast internal conversion (IC) process. This study aims to provide theoretical insights into the development of efficient chemosensors which are switched on through the ESIPT process.