Insights into the solvent-polarity-associated hydrogen bonding interactions and ESIPT reactions for DBOX fluorophore: a theoretical investigation

Abstract

Inspired by the exquisite design of distinguished optical materials, novel organic molecules with remarkable characteristics of excited-state intramolecular proton transfer (ESIPT) have emerged as a prominent and captivating research topic. In this study, our primary focus lies in exploring the intricate dynamics of the excited state in 2-(5-(benzo[d]thiazol-2-yl)-1,3,4-oxadiazol-2-yl)-5-(diethylamino)phenol (DBOX), an extraordinary reversible molecular fluorophore that undergoes single-crystal-to-single-crystal transition. By investigating four distinct aprotic solvents with varying degrees of polarity, we unequivocally validate the significant impact of solvent polarity on photo-induced hydrogen bonding interactions, charge redistribution, and associated excited-state intramolecular proton transfer (ESIPT) phenomena. Through meticulous comparison and precise quantification of reaction barriers in diverse solvent environments, our groundbreaking findings strongly suggest that solvents with low polarities effectively facilitate the ESIPT reaction for DBOX fluorophore.