Emerging ground and excited state dipole moments and external electric field effect on electronic structure. A solvatochromism and theoretical study on 2-((phenylimino)methyl)phenol derivatives

Abstract

The absorption and fluorescence spectra of three 2-((phenylimino)methyl)phenol derivatives have been evaluated in a series of organic solvents. The ground state (μg) and excited state (μe) dipole moments are determined by means of Lippert–Mataga, Bakhshiev, Kaski–Chamma–Viallet and Reichardt solvatochromic shift methods based on the solvent polarity parameters. Excited state dipole moments are found as larger than the ground state dipole moment due to substantial redistribution of the π-electron density in more polar excited state and thus resonance structures of 2-((phenylimino)methyl)phenol derivatives are analyzed. Solute–solvent interactions are analyzed by means of linear solvation energy relationships (LSER) using dielectric constant function f(ε), refractive index function f(n) and Kamlet–Taft parameters (H-bond donor ability, α and H-bond acceptor ability, β). External electric field (EF) effect on HOMO–LUMO gap (HLG) and dipole moment are investigated by B3LYP, LDA and GGA methods. Density of states (DOS) and HOMO, LUMO plots are also investigated by the same methods.