A theoretical exploration and regulating about the excited state process for 2-(4-(diphenylamino)phenyl)-3-hydroxy-4H-chromen-4-one system

In the present work, density functional theory (DFT) and time-dependent density functional theory (TDDFT) methods have been performed to explore the ground-state and excited-state intramolecular hydrogen bonding interactions for 2-(4-(diphenylamino)phenyl)-3-hydroxy-4H-chromen-4-one (2-DHC) system. We demonstrate that the intramolecular hydrogen bond formed in the ground state should be strengthened in the first single excited state by comparing the bond parameters and infrared (IR) vibrational spectra, which provides the possibility for excited-state intramolecular proton transfer (ESIPT) reaction. The calculations about hydrogen bonding energy further confirm the strengthening hydrogen bond. The intramolecular charge transfer (ICT) around hydrogen bonding moieties upon photoexcitation promotes the ability to attract hydrogen proton, which reveals the ESIPT tendency. In view of four different polarities solvents, we construct the potential energy curves along with ESIPT path and search the transition state (TS) structure for ESIPT reaction. We clarify the ESIPT mechanism for 2-DHC molecule, based on which we also present the ESIPT reaction could be regulated and controlled by solvent polarity