Pt(II) and Ni(II) complexes of octahydropyrrolo[3,4-c]pyrrole N -benzoylthiourea derivatives: Synthesis, characterization, physical parameters and biological activity

Abstract In this study, four novel Pt(II) and Ni(II) complexes of octahydropyrrolo[3,4-c]pyrrole, consisting of pyrrolidine fused to pyrrolidine-2,5-dione, N -benzoylthiourea derivatives were synthesized and their structural characterization was performed by NMR, FT-IR, MS, HRMS and elemental analysis techniques and single crystal X-ray diffraction studies. The octahydropyrrolo[3,4-c]pyrrole N -benzoylthiourea compound 3c crystallizes triclinic, with space group P-1. Pt(II) and Ni(II) ions created cis -complexes Pt(II) 4c and Ni(II) 5a forming distorted square-planar structures in orthorhombic space groups Pnma and Pbca, respectively. Furthermore, the ligands behave as bidentate and bind to the metal atom via the S and O atoms. Acid dissociation constants of the ligands were determined by potentiometric titration method in 25% (v/v) acetonitrile-water hydroorganic solvent at 25 ± 0.1 °C, at an ionic background of 0.1 mol/L of NaCl using the HYPERQUAD computer program and at least three acid dissociation constants were determined for each ligand. Stability constants of Pt(II) and Ni(II) complexes of the ligands were determined by potentiometric titration under the same conditions as stated above. Determination of the stability constant studies show that the ligands tend to form with Pt(II) ion in acidic medium as 1:1 (M:L) and in basic medium as 1:2 (M:L), but the ligands tend to form with Ni(II) ion in both acidic medium and basic medium as 1:2 (M:L). Antibacterial activity of the ligands and their complexes was investigated against S . aureus , B . subtilis , A . hydrophila , E . coli and A . baumannii standard bacterial strains. The ligands and their Pt(II) and Ni(II) complexes exhibited antibacterial activity against mentioned bacterial strains in the range of 62.5–125 μg/mL, 62.5–250 μg/mL and 62.5–125 μg/mL, respectively. Antimycobacterial activity of the compounds was investigated against the M. tuberculosis H37Rv strain. The compounds exhibit antimycobacterial activity in the range of 40–80 μg/mL.