Investigation of excited state proton transfer mechanism for 2-(benzo[d]thiazol-2-yl)naphthalene-1,3-diol in different solvents

Abstract This work systematically investigates solvent effects on hydrogen bond strength and excited-state intramolecular proton transfer (ESIPT) behaviour of 2-(benzo[d]thiazol-2-yl)naphthalene-1,3-diol (DHT) chromophore. The calculated electronic spectra accord with experimental observation. Our work confirms hydrogen bond is enhanced in excited state, which facilitates ESIPT behaviour. The Hirshfeld charges analysis reveal that effect of different solvents on electronegativity of proton donor and acceptor results in change of hydrogen bond strength. It follows that strength of hydrogen bond is gradually weakened with the increase of solvent polarity in excited state. The constructing potential energy profiles show that with the decreased solvent polarity, ESIPT is more likely to occur.