Synthesis, crystal structures, biological and thermal decomposition evaluation of homo and heteroleptic Zn(Ⅱ) dithiocarbamate complexes and use of Zn(Ⅱ) dithiocarbamate to prepare zinc sulfide nanoparticles

New functionalized homoleptic and heteroleptic zinc(II) and cadmium(II) dithiocarbamate complexes of formulae [Zn(^cpebdtc)₂] (1), [Zn(^cpebdtc)₂(py)] (2), [Cd(^cpebdtc)₂] (3), [Cd(^cpebdtc)₂(2,2ʹ-bipy)] (4) (where, ^cpebdtc = N-cyclopropyl-N-2-ethoxybenzyldithiocarbamate; py = pyridine and 2,2ʹ-bipy = 2,2ʹ-bipyridine) were synthesized and then characterized by CHNS analysis, IR, UV–Vis., ¹H and ¹³C NMR spectroscopy. The molecular structures confirmed by X-ray crystallography revealed that complexes 1 and 2 adopt distorted tetrahedral and pentagonal geometry with ZnS4 and ZnS4N chromospheres respectively. Supramolecular networks are being sustained by C[sbnd]H…π and C[sbnd]C intermolecular interactions. Anti-leishmanial activity evaluation revealed the promising anti‑promastigote activity of complexes 1 and 2 with IC₅₀ values 4.6 ± 0.41 and 3.37 ± 0.28 μg mL⁻¹ respectively. The DNA binding study confirmed that complexes 1 and 2 bind effectively with Ct-DNA through groove binding/electrostatic interaction as suggested by hyperchromism and it was further validated by molecular docking. All the complexes showed potential antioxidant activity. TG analyses showed one step for 1, 3 and two step decomposition for 2, 4 complexes with the formation of binary ZnS (1, 2) and CdS (3, 4) materials. Complex 1 was utilized as a single source precursor to prepare ZnS nanoparticles. Single phase (rhombohedral) of ZnS nanomaterial was confirmed by X-ray diffraction analysis. TEM micrograph revealed spherical shape of ZnS nanoparticles with dimensions in the nanoscale (50–80 nm).