Theoretical insights into electronically excited-state hydrogen-bonding effects and ESIPT mechanism for 2-benzothiazol-2-yl-4-methoxy-6-(1,4,5-triphenyl-4,5-dihydro-1H-imidazol-2-yl)-phenol compound

In this work, DFT and TDDFT approaches are performed to make a detailed exploration about excited state behavior for 2-Benzothiazol-2-yl-4-methoxy-6-(1,4,5-triphenyl-4,5-dihydro-1H-imidazol-2-yl)-phenol (BTImP) system. Combining geometrical parameters and theoretical infrared analyses, we prove hydrogen bond of BTImP is strengthening in S1 state. Insights into frontier molecular orbitals, we present charge redistribution facilitates excited state intramolecular proton transfer (ESIPT) reaction. Probing into potential energy curves, we confirm the ultrafast ESIPT mechanism for BTImP. Furthermore, given different solvent polarities, we deem the ESIPT behavior of BTImP could be controlled. We wish this work could facilitate developing novel sensors in future.