Molecular Conformational Analysis, Spectroscopic Characterization, Intramolecular Hydrogen Bonding and Natural Bond Analysis of (E,Z)-2-(4- Amino-5-oxo-3-(thiophene-2-ylmethyl)-4,5-dihydro-1,2,4-triazole-1-yl)-N'- (thiophene-2-ylmethylene) Acetohydrazide

The optimized structural parameters and electronic properties including frontier molecular orbital (FMO) analysis, molecular electrostatic potential and NBO charge analysis of (E,Z)-2-(4- amino-5-oxo-3-(thiophene-2-ylmethyl)-4,5-dihydro-1,2,4-triazole-1-yl)-N'-(thiophene-2-ylmethylene) acetohydrazide were investigated by using density functional theory (DFT) at B3LYP/6-311++G(d,p) level. The global reactivity parameters were evaluated in accordance with the energy values of HOMO and LUMO of each determined conformer. The molecule was experimentally characterized by means of FT-IR and NMR spectroscopic methods and also theoretically by B3LYP/6-311++G(d,p) and B3LYP/cc-pVTZ method (FT-IR and NMR, respectively). The theoretical results of spectroscopic analysis show good agreement with experimental outcomes. The natural bond orbital (NBO) analyses for studied conformers were performed at B3LYP/6-311++G(d,p) level to find hyperconjugative interactions as well as intramolecular hydrogen bond interaction. Besides, theoretical results indicate that the optimized structure of conformer E and Z possesses N128;’H···N and N128;’H···S weak hydrogen bonding, respectively.