Specific and non-specific interaction effect on the solvatochromism of some symmetric (2-hydroxybenzilydeamino)phenoxy Schiff base derivatives

Abstract

In this present work, solvatochromic behavior, specific and non-specific solute–solvent interactions and electronic structure of (2-hydroxybenzilydeamino)phenoxy Schiff base derivatives have been investigated by using electronic absorption spectra in solvent media with different polarities. Electronic absorption spectra are observed to exhibit three main electronic transition bands along with the fourth band which comes into existence from specific solute–solvent interactions. Solute–solvent interaction mechanism and solvatochromic behavior of the studied molecules have been analyzed and evaluated by means of four linear solvation energy relationship (LSER) methods such as Kamlet–Taft parameters, Catalan parameters, Marcus optical dielectric function and Dimroth–Reichardt ET solvent parameter. Achieved results indicate that the mechanisms which control the specific and non-specific solute–solvent interactions are considerably effected by the characteristics of substituents and molecule geometry. According to ET solvent parameter, electronic absorption spectra of (2-hydroxybenzilydeamino)phenoxy Schiff base derivatives exhibit positive solvatochromism. Tautomeric structure and excited state intramolecular proton transfer (ESIPT) have been elucidated by means of resonance structure. A 2D solute–solvent interaction model is investigated theoretically. 3D molecular structure, HOMO (the highest occupied molecular orbital), LUMO (the lowest unoccupied molecular orbital), molecular electrostatic potential (MEP) and solvent accessible surface (SAS) are calculated by using the DFT-B3LYP method.