Organotin(IV) complexes with 5-aminoisophthalic acid: Synthesis, characterization, theoretical study, and biological activities

Organotin(IV) carboxylates with the general formula [Bu-2(Cl)Sn](2)L (1), (Me3Sn)(2)L (2), and (Bu3Sn)(2)L (3) were synthesized by stirring 5-aminoisophthalic acid with KOH in methanol and with following addition of Bu2SnCl2/Me3SnCl/Bu3SnCl under stirring conditions. The complexes were characterized by the microanalysis, IR, and H-1 NMR spectroscopies, mass spectrometry, and by the DFT and semi-empirical methods. The data on the elemental analysis and mass fragmentation agree well with the chemical composition of the complexes. The IR spectroscopy demonstrated a chelating coordination mode of the carboxylate group. The H-1 NMR spectroscopy confirmed the 5-coordinated geometry of the organotin(IV) derivatives. The DFT and semi-empirical calculation of the complex 2 supported an asymmetric coordination behavior of the carboxylate group. The complexes 2 and 3 exhibited an intercalating binding with salmon sperm DNA. Significant antibacterial/antifungal potential of the complexes was confirmed by the disc diffusion method and evaluation of the minimum inhibitory concentration (MIC). The hemolytic activity of the complexes is higher than that of a free ligand and PBS and sufficiently lower than that of triton X-100.