TD-DFT study of the excited state intramolecular proton transfer (ESIPT) mechanism and photophysical properties in coumarin–benzothiazole derivatives: substitution and solvent effects

The photo-switching mechanism in the coumarin–benzothiazole dyes ( BT–Cou–R 1–8 ; R 1–8 = H, NH 2 , OH, OCH 3 , CH 3 , CF 3 , CN and NO 2 ) with potential application in drug delivery was investigated at the TD-PBE0/6-311++G(d,p) level of theory in the gas phase and three solvent media.