Effects of intramolecular and intermolecular hydrogen bonding on the ESIPT process in 2-(2′-hydroxyphenyl)imidazo[1,2-a]pyridine derivative

We investigate the excited-state intramolecular proton transfer (ESIPT) process and luminescence mechanism of a 2-(2′-hydroxyphenyl)imidazo[1,2-a]pyridine derivative (HIP-Br) in dichloromethane (DCM) and dimethyl sulfoxide (DMSO) using both implicit and explicit solvation models. Computational results reveal that the ESIPT process of HIP-Br proceeds efficiently in DCM regardless of the solvation model. In contrast, in DMSO, the ESIPT process is suppressed under the explicit solvation model due to the formation of intermolecular hydrogen bonds between HIP-Br and DMSO molecules, which disrupt the intramolecular hydrogen bond. This study underscores the importance of considering explicit solute–solvent interactions when modeling excited-state processes in hydrogen-bonding solvents.