Synthesis and evaluation of molecular structure from torsional scans, study of molecular characteristics using spectroscopic and DFT methods of some thiosemicarbazones, and investigation of their anticancer activity

Synthesis of 2-((2-aminopyridin-3-yl) methylene) hydrazinecarbothioamide (APHT) was attempted. Elemental analysis and NMR spectra were used to ascertain its formation. Torsional potential energy scans for all five of its rotating bonds were made to get approximate dihedral angles. UV–Vis spectra were measured for APHT and 2-((2-aminopyridin-3-yl) methylene)- N -methylhydrazinecarbothioamide (APMHT). Their anticancer activity was determined experimentally, for human carcinoma cell lines pertaining to liver, colorectal, and lung. For both APHT and APMHT, frontier molecular orbital parameters, NLO behaviour, and NBO characteristics were determined using DFT/B3LYP/6-311++G(d,p) level of theory. TD-DFT was used to compute absorption maxima ( λ max ) of electronic transitions for both molecules in DMSO- d 6 solvent. Frontier molecular orbitals were used to understand origin of UV–Vis spectra and chemical reactivity of the two molecules. Good agreement was found between measured and computed structure parameters. This is also true of experimental and theoretical UV–Vis spectra. The computations demonstrated that both the molecules were good for NLO applications, which was substantiated by NBO analysis. Existence of bifurcated intramolecular hydrogen bond was predicted for both APHT and APMHT.