Synthesis, characterization, and biological evaluation of some metal complexes containing N and S donor atoms

Abstract

Eight new bipyridine adducts of Zn(II) and Ni(II) dithiocarbamate complexes have been prepared from the reaction of Zn(II) and Ni(II) complexes of N-ethyl-N-phenyldithiocarbamate and 4,4′ dipyridine, 4,4′-dimethyl-2,2′-bipyridine, 4,4′-dimethoxy-2,2′-bipyridine, 4,4′-ditertbutyl-2,2′-bipyridine. The resulting adducts were represented as [M(L1)2(DP)], [M(L1)2(DMeB)], [M(L1)2(DMxB)] and [M(L1)2(DTB)] respectively (where M = Zn or Ni). The structural configuration of these adducts was established using various spectroscopic techniques. The obtained data from the spectroscopic studies revealed a change in the tetrahedral configuration of the parent complexes to octahedral coordination in the adducts due to an additional metal-nitrogen bond. The formation of this bond was established by a considerable shift in the peaks around the metal-nitrogen (M−N) coordination upon the formation of the adducts. The study of biological properties including cytotoxicity, antioxidant, and anti-inflammatory properties were carried out. No noticeable trends were reported in all the studies despite the concentration-dependent profile shown in the assays and the structural similarities of the compounds. These adducts, nevertheless, showed good antioxidant activity in the DPPH assay, with IC50 ranging between 3.78 and 4.87 µg/mL which is better than the standard ascorbic acid (4.96 µg/mL). Also, in the cytotoxicity study, the adducts [Zn(L)2DMeBp] (1) and [Ni(L)2 DTBp] (6) showed the best activity against the mutating human cervical cancer (HeLa) and embryo kidney (HEK 293) cell lines and better than the standard 5-Flurouracil. The molecular docking studies further revealed that the adducts had a good binding affinity to the drug targets used for the study.