Crystal structure analysis of three (E)-N-(3-methyl, 5-fluorinephenyl)-2-(4-substituted benzylidene)thiosemicarbazone derivatives: Experimental and theoretical studies

Abstract

Three novel thiosemicarbazone compounds (E)-N-(3-methyl, 5-fluorine phenyl)-2-(4-benzylidene)thiosemicarbazone (1), (E)-N-(3-methyl, 5-fluorine phenyl)-2-(4-methylbenzylidene)thiosemi-carbazone (2) and (E)-N-(3-methyl, 5-fluorine phenyl)-2-(4-chlorobenzylidene)thiosemicarbazone (3) were synthesized and characterized. UV-visble absorption spectra of the targeted compounds were described using the method of combing the experiment and theory. The single crystal X-ray diffraction was used to obtain these crystal structure data. The experimental values from X-ray diffraction studies were consistent with ones calculated from the quantum chemical theory. Under the B3LYP/6-31+G (d, p) basis set, the properties and types of intermolecular interaction were discussed by Hirshfeld surface analysis. Reduced density (RDG) theory, atom in molecules (AIM) method and independent gradient model (IGM) indicated that the intramolecular weak interactions maintained molecular structure stability. The quantum molecular descriptions such as molecular electrostatic potential (ESP) and Fukui functions were used to explore possible reactive sites. Combining hyper-conjugative interactions theory with electron delocalization theory, Natural bond orbital (NBO) was used to predict the stability of the three compounds. The electronic transitions among orbitals within the molecules were confirmed by the combination of UV-visble spectra and HUMO- LUMO analysis. Molecular docking was used to simulate the interactions of the synthetized compounds with the antifungal receptor protein (1NMT) at active pocket. Eventually, in vitro antifungal activity of the synthetized compounds was evaluated by the disk diffusion method.