SOLVATOCHROMISM STUDIES ON UV SPECTRA OF 4,5-DISUBSTITUTED-1,2,4-TRIAZOLINE-3-THIONES

The influence of a series of organic solvents on the UV spectra of investigated 1,2,4-triazoles, was studied by implementing solvatochromic theory. As a part of our efforts to interpret the effects of sol-vent polarity and hydrogen bonding on the absorption spectra of previously synthesized 1,2,4-triazoline-3-thiones, the study design was based on the linear solvation energy relationship (LSER) concept using Kamlet-Taft solvatochromic parameters: π*, α and β. Accordingly, by dividing the solvents into two groups (protic and aprotic) it was ascertained that improved solvatochromic three-correlation models for the group of protic solvents were obtained. The results show that the solvent effect on UV absorption spectra of in-vestigated thiones was very complex and strongly dependent on the nature of the substituent in positions 4 and 5 in 1,2,4-triazole moiety. Moreover, the statistical evaluation of the models (R, SD, Q2 and PRESS/ SSY) showed satisfactory values