Investigation of solvent effects on electronic absorption spectra of some substituted 1,2,4-triazoline-3-thiones

Abstract

The influence of the polarity of the solvent and hydrogen bonding on the electronic absorption spectra of some previously synthesized substituted 1,2,4-triazoline-3-thiones was studied. The electronic absorption spectra of investigated compounds were recorded in the region from 190 nm to 360 nm in eight protic (water, ethylene glycol, methanol, ethanol, propan-1-ol, propan-2-ol, butan-1-ol and tert-butanol) and five aprotic (acetonitrile, chloroform, dimethylsulfoxide, dimethylformamide and dioxane) solvents. Their absorption maxima appeared in the region between 250 nm and 260 nm as a result of the electron transitions in the 1,2,4-triazoline-3-thione ring. Using the method of linear solvation energy relationships (LSER), the effects of solvent polarity and hydrogen bonding on the electronic absorption spectra were interpreted. The results have shown that the influence of the aprotic solvents is more significant compared to that of the protic solvents.