A computational and spectral analysis of 2-arylhydrazone thiazolo[3,2-a]pyrimidine derivatives containing p-carboxyphenyl fragment

Abstract

Experimental Raman and IR spectra of arylhydrazone thiazolo[3,2-a]pyrimidines containing a p-carboxyphenyl moiety are reproduced using E- and Z-conformational calculations. When the aryl group is rotated, two diastereomeric rotamers (1- and 2-) can be made from the E- and Z-isomers of ortho-methoxyphenyl-substituted thiazolopyrimidine. Therefore, for compound 1, four isomers (E1, E2, Z1, and Z2) should be considered. For two distinct solvents, the conformations’ free energies and populations were computed. The experimental vibrational spectra of synthesized hydrazones have been analyzed and the bands categorized. Using infrared spectroscopy, the intermolecular H-bond between thiazolopyrimidines and dimethylformamide was studied. The thiazole and pirimidine rings of the obtained thiazolopyrimidine arylhydrazones molecules 1 and 2 are home to their HOMO and LUMO, which show a strong bond conjugation and an almost flat molecular skeleton. The molecule’s reactivity changes and there is a notable delocalization of charge with conformational changes. The thiazolopirimidines’ reactivity was described using descriptors. It was found that in terms of chemical potential, electrophilic index, ionization energy, and electron affinity, the Z-form was inferior to the E-form. The molecules are the same softness, but the E-form has a greater dipole moment.