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New binuclear tin(IV) complexes based on salicylic Schiff bases and diphenyltin oxide Ph₂SnO were obtained. The structures of the complexes were confirmed by ¹H, ¹³C and ¹¹⁹Sn NMR spectroscopy and X-ray diffraction analysis (CCDC 2433411). UV-Vis spectroscopy of complexes 1–4 showed that a bathochromic shift of all ligand absorption bands was observed upon complexation with the metal fragment. The ability of complexes 1–4 to undergo electrochemical transformations was investigated by cyclic voltammetry. In all cases, the oxidation and reduction of the complexes are irreversible. In the cases of complexes 2–4 with a conjugated bridge, the oxidation of two metal fragments occurs at one potential, whereas complex 1 with an unconjugated adipic bridge has two peaks on the oxidation curve at different potentials, which is probably since the oxidation of two different ‘ends’ of the molecule occurs at different potentials.

The interaction of three copper(II) complexes — Cu(Gly)₂⁰, Cu(Bipy)₂²⁺, and Cu(Bipy)Gly⁺ — with glutathione in aqueous solution (pH 7.4, 0.2 M NaCl, 25°C, с_Cu = (1–10) × 10^–4, с_GSH = 1.0 × 10^–3 M) was studied. These and similar complexes are often used in biological experiments to test anticancer and antimicrobial activity. It was shown that under physiological conditions copper(II) complexes are almost irreversibly converted into a more stable form of copper(I) thiolate complexes. The individuality of the initial complexes is completely lost. In all cases, the redox interaction of the copper(II) complexes with glutathione was rapid and quantitative. The main products were copper(I) bisthiolate complex and glutathione disulfide.

Synthesized N-[2-[(E)-2-furylmethyliminomethyl)phenyl]-4-methyl-benzenesulfamide (HL) and complexes of Cu(II), Ni(II), Co(II) based on its ML₂ composition. The composition, structure, and spectral properties of the obtained compounds were studied using elemental analysis, ¹H NMR (for HL), IR spectroscopy, and electron absorption spectroscopy. The crystal structure of Cu(II), Ni(II), and Co(II) complexes was determined by X-ray diffraction (CCDC No. 2420740, 2420738, and 2420739, respectively). It is shown that two deprotonated ligands are chelated coordinated to metal ions by nitrogen atoms of the tosylamine and azomethine fragments of the ligand. The geometry of the surroundings of copper(II), nickel(II), and cobalt(II) ions corresponds to a strongly distorted tetrahedron. The electronic absorption spectra of HL and metal complexes have been studied. Azomethine HL and metal complexes were studied for antibacterial, protistocidal, and fungistatic activities. It was found that all compounds did not have fungistatic activity against Penicillium italicum, antibacterial activity against Staphylococcus aureus and Escherichia coli, and only for HL showed procystoid activity against Colpoda steinii at the level of the reference drug chloroquine.