Solvatochromism and electronic structure of some symmetric Schiff base derivatives

Abstract

In this present work, we have investigated electronic absorption spectra of three symmetric Schiff bases in fourteen spectroscopic grade solvents which have different polarities. The electronic transitions have been evaluated with regard to solvent polarity. The electronic transition mechanisms and solvatochromic behavior of the investigated molecules are determined by using four different linear solvation energy relationship (LSER) methods, such as the Kamlet–Taft Parameters, the Catalan parameters, the Marcus optical dielectric function and the Reichardt–Dimroth ET solvent parameter. Electronic transitions are found to exhibit four electronic bands. Electronic absorption spectra are observed to display positive solvatochromism with the change of solvent polarity. Enol–keto tautomerism and excited state intramolecular proton transfer are analyzed by means of resonance structures. LSER results indicate that electronic transitions are dominantly controlled by induction–dispersion interactions and that hydrogen bond acceptor capacity is relatively more effective on solvatochromic behavior compared to that of hydrogen bond donor capacity.