Synthesis, structure investigation, spectral characteristics and biological activities of 4-benzyl-3- (2-hydroxyphenyl)-1h-1,2,4-triazole-5(4h)- thione

This work presents the characterization of 4-benzyl-3- (2-hydroxyphenyl)-1H-1,2,4-triazole-5(4H)- thione (I) by quantum chemical calculations and spectral techniques. The molecular geometry, vibrational frequencies and gauge including atomic orbital (GIAO) 1H and 13C NMR chemical shift values of I in the ground state have been calculated using the density functional method (B3LYP) with the 6−31G(d,p) basis set. To determine conformational flexibility, the molecular energy profile of the title compound was obtained by using B3LYP/6‒31G(d,p) method with respect to the selected torsion angle, which was varied from –180° to +180° in steps of 10°. The calculated results show that the optimized geometry can well reproduce the crystal structure, and the theoretical vibrational frequencies and chemical shift values show good agreement with experimental values. In addition, DFT calculations of molecular electrostatic potentials and frontier molecular orbitals of I were carried out at the B3LYP/6−31G(d,p) level of theory. The title compound was screened for antibacterial, antifungal and antioxidant activities. Keywords: 1,2,4-triazoles, DFT, Biological effects