Insights into atomic‐electronegativity‐controlled excited state intramolecular proton transfer behavior for the novel oxazolonapthoimidazo[1,2‐a]‐pyridine (ONIP) compound: A time‐dependent density functional theory study

Abstract

AbstractIn this work, we mainly focus on probing into the effects of atomic electronegativity on photo‐induced hydrogen bond (i.e., O–H···N) effects and excited state intramolecular proton transfer (ESIPT) processes for a novel fluorescent chemical probe ONIP derivatives (i.e., ONIP‐O, ONIP‐S, and ONIP‐Se). First, insights into optimized structural geometries and related infrared vibrational spectra, we clarify that the hydrogen bond O–H···N interaction could be strengthened via photoexcitation. Further, via predicting hydrogen bonding energy EHB, we quantificationally present that the S1‐state hydrogen bonding strengthening behavior should be more distinct with lower atomic electronegativity. When it comes to vertical photo‐induced excitation, the intramolecular charge transfer process happens and the charge redistribution plays roles in promoting ESIPT behavior. It is worth mentioning the energy gap between highest occupied molecular orbital and lowest unoccupied molecular orbital show that low atomic electronegativity should be more favorable to ESIPT process. Finally, based on the restricted optimization method, we construct the potential energy curves along with hydrogen bond wire for ONIP‐O, ONIP‐S, and ONIP‐Se. By exploring the conformation of potential energy curves and potential energy barriers, we disclose the detailed atomic‐electronegativity‐controlled ESIPT dynamical behaviors for ONIP system.