Structural characterization and molecular docking studies of biologically active platinum(II) and palladium(II) complexes of ferrocenyl Schiff bases

Abstract

Four new Pt(II)/Pd(II) complexes were prepared, [Pt(L1)(H2O)2]Cl2·3H2O (1), [Pd(L1)(H2O)2]Cl2·4H2O (2), [Pt(L2)(H2O)Cl]Cl·5H2O (3) and [Pd(L2)(H2O)Cl]Cl·3H2O (4). Ligands derived from 2-acetylferrocene with 4‐nitro‐1,2‐phenylenediamine (L1) and with 3,4-diaminopyridine (L2) were synthesized. Structures of complexes were confirmed based on different spectroscopic techniques. The results showed that synthesized complexes offered 1:1 metal‐ligand ratios. All complexes were electrolytes and had square planar structure. IR spectra designated that Schiff bases were coordinated to Pt/Pd ions in a bidentate manner, N,N donor sites of azomethine-N and amino-N. Thermal behavior of these chelates indicated that hydrated complexes lost water molecules of hydration in the first step and was immediately followed by decomposition of the ligand molecules in the subsequent steps. Investigation of bioactivity for complexes and ligands exposed their moderate antibacterial activities against four Gram positive bacteria (Staphylococcus aureus, Bacillus cereus, Bacillus subtilis and Streptococcus faecalis) and four Gram negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Neisseria gonorrhoeae and S. typhimrium). In cytotoxicity studies with MCF-7 cell line, all compounds exhibited good cytotoxic properties, in which complex (4) had the lowest IC50 value (11.0 µg/mL). Finally, the antibacterial and cytotoxicity studies of prepared compounds were confirmed by comparing experimental results with theoretical ones from molecular docking studies with three different protein receptors (3HB5, 3Q8U and 3T88).