Antimony(III) Derivatives Containing Heterocyclic- and N-Alkyl-N-Phenyl Dithiocarbamate Moeities Along With Computational Analysis, Antimicrobial and Anticancer Studies

Abstract

Six heteroleptic antimony(III) dithiocarbamate complexes of the type [R″CS₂Sb{S₂CN(C₆H₅)R′}₂] [where R′ = –CH₃ R″ = 4-methylpiperazine (C-1); R′ = –C₂H₅ and R″ = 4-methylpiperazine (C-2); R′ = –CH₃ and R″ = 1,2,3,4-tetrahydroquinoline (C-3); R′ = –C₂H₅ and R″ = 1,2,3,4-tetrahydroquinoline (C-4); R′ = –CH₃ and R″ = 4-methylpiperidine(C-5); R′ = –C₂H₅ and R″ = 4-methylpiperidine (C-6)] were synthesised and characterised. Physicochemical and structural elucidations of the complexes were accomplished by elemental analyses, FT-IR, ¹H, ¹³C-NMR spectral studies, and mass spectrometry. The thermogravimetric (TGA) and differential thermal analysis (DTA) were investigated for a representative derivative C-4 in order to confirm the thermal resistivity and to get the Sb₂S₃ as the final product of the thermal decomposition. The theoretical study with density functional theory (DFT) has been utilised to optimise the structure of complexes C-1, C-3 and C-5 along with their corresponding ligand moieties for HOMO-LUMO energy calculations. Distorted octahedral geometry has been proposed on the basis of energy calculations of two expected optimised geometries. The spectral and computational data have revealed the anisobidentate mode of coordination in the complexes. All complexes displayed significant antibacterial activity against S. aureus, E. coli and antifungal activity against A. niger and Fusarium strains even at low concentrations. Notable anticancer activity against MCF-7 (human breast) and HCT-116 (colorectal) cancer cell lines with IC₅₀ values of 8.826 ± 0.26 μg/mL and 50.86 ± 0.10 μg/mL, respectively, for the representative complex C-1 has been observed and further revealed its biological potency for future drug discovery.