Optical Absorption Spectra of (E)-2-(2-Aryl-1-Cyanovinyl)-4-Cyclopropylthiazoles

Abstract

The optical absorption spectra of (E)-2-(2-aryl-1-cyanovinyl)-4-cyclopropylthiazole derivatives with different substituents in the para position of the aryl ring have been studied. The measurements were carried out in dimethylformamide solution. The introduction of electron-withdrawing substituents leads to a bathochromic shift since these substituents promote delocalization of the thiazole ring nitrogen and sulfur unshared electron pairs. The absorption bands at 250–450 nm arise from HOMO → LUMO and HOMO–1 → LUMO transitions.