Spectroscopic, computational, anti-bacterial studies of bivalent metal complexes of N-picolyl-amine dithiocarbamate

Abstract

This study reports the synthesis of seven picolylamine dithiocarbamate complexes of M(II) {M =CoII (1), NiII (2), CuII (3), PdII (4), ZnII (5), CdII (6) and HgII (7)}. CHN analysis, conductivity measurements, magnetic susceptibility measurement, FT-IR, 1H and 13C-NMR, SEM, and XRD were used to investigate the structural geometries of the complexes. The dithiocarbamate ligand coordinates to the M(II) ion in a bidentate mode through sulfur atoms forming a square planar or tetrahedral geometry. Moreover, the surface structural analysis revealed nano-pattern properties. For instance, complexes of Cd(II) and Hg(II) showed a nano-flower pattern, averaging 2–5 µm. Furthermore, the obtained complexes exhibited biological activity properties. The results showed that the new metal (II) compounds possessed remarkable antibacterial inhibition activity against both Gram-positive and Gram-negative bacteria. Additionally, the complexes [Ni(PA-dtc)2], [Cu(PA-dtc)2], and [Pd(PA-dtc)2] were theoretically studied and their quantum parameters were evaluated using Gaussian 09 program at B3LYP/SDD level of theory. The optimized structures of all of the three complexes showed square planar geometry. The calculated bond lengths showed close values, specifically for CSS and CN group, which suggests a partially double bond character. Other quantum parameters have evaluated and showed similar properties such as the total energy, HOMO-LUMO energy gap, Affinity, Hardness, and dipole moment.