Theoretical Insights on Solvent Control of Intramolecular and Intermolecular Proton Transfer of 2-(2'-Hydroxyphenyl)benzimidazole.

Excited-state proton transfer (ESPT) processes of 2-(2'-hydroxyphenyl)benzimidazole (HBI) and its complexation with protic solvents (HO, CHOH, and NH) have been investigated by both static calculations and dynamics simulations using density functional theory (DFT) at B3LYP/TZVP theoretical level for ground state (S) and time-dependent (TD)-DFT at TD-B3LYP/TZVP for excited state (S). For static calculations, absorption and emission spectra, infrared (IR) vibrational spectra of O-H mode, frontier molecular orbitals (MOs), and potential energy curves (PECs) of proton transfer coordinate were analyzed. Simulated absorption and emission spectra show an agreement with available experimental data.