Combined experimental and theoretical studies of diorganotin(IV) complexes of 1,2,4-triazole based Schiff base: Synthesis, spectroscopic investigation, DFT calculation, antifungal activity

Abstract

Two novel diorganotin(IV) compounds of Schiff base (HL) with a general formula of R2Sn(L)Cl (where R equals n-Bu(1) or Ph (2)) have been formed and structurally identified. The identification was made through examination of various properties including elemental analysis, FT-IR, multinuclear NMR, 2D-HMQC, ESI-MS, and UV–vis analysis. The proposed structure for these organotin(IV) derivatives is a distorted tetrahedron surrounding tin, with the Schiff base ligand acting as a monoanionic monodentate by coordinating through the Ohydroxyl group. The density functional theory (DFT) calculation was accomplished at the B3LYP/6-31G(d,p)/Def2- SVP(Sn) level. The MEP map was used to recognize the reactive sites on the molecules, and atomic charges were determined at specific atoms. The global reactivity descriptors and the Frontier MO's were calculated using conceptual-DFT to understand the behavior of the structure and reactivity. We compared the experimental and simulated vibrational frequencies and found a strong correlation. A time-dependent DFT method utilizing the IEFPCM model was employed to determine the simulated UV–vis spectrum. Both of the analyzed complexes were tested for their ability to inhibit fungal growth in vitro against selected fungal strains. The significant antifungal effect of complexes could be observed against all strains.