Synthesis, characterization, antimicrobial, and DNA cleavage evaluation of some organotin(IV) complexes derived from ligands containing the 1H-indole-2,3-dione moiety

New Schiff bases 5-iodo-indol-2,3-dionehydrazinecarboxamide ((LH)-H-1) and 5-iodo-indol-2,3-dionehydrazinecarbothioamide ((LH)-H-2) and their organotin(IV) complexes have been synthesized. The biologically potent ligands interacted with the Sn(IV) metal ion in 1: 1 and 1:2 molar ratios, respectively, in dry methanol. Tentative structural conclusions of organotin( IV) complexes are described with the support of elemental analyses, melting points, and molecular weight determinations, infrared, nuclear magnetic resonance (H-1, C-13, and Sn-119), and ultraviolet-visible light spectroscopic studies. The spectroscopic data showed that the ligands are monobasic bidentate, coordinating through nitrogen and sulfur/oxygen atoms. Thus, suitable trigonal bipyramidal geometry and octahedral geometry have been suggested for the 1: 1, and 1: 2 metal complexes, respectively. The ligands and their complexes have been tested against various microbes for their in vitro antimicrobial activities. All complexes exhibit good antibacterial activity against the two bacterial species Escherichia coli and Staphylococcus aureus and remarkable antifungal activity against the two fungi Fusarium semitectum and Aspergillus flavus with respect to their corresponding ligands. The DNA cleavage efficiency of the ligands and the complexes has also been examined and discussed using gel electrophoresis technique, which showed the cleavage of DNA by all the metal complexes and ligands.