Dinuclear bismuth(III) complex constructed by isoniazid‐derived Schiff base: Synthesis, crystal structure, and biological activity

Abstract

A new bismuth(III) Schiff‐base complex [Bi2(HL)2(NO3)4(CH3OH)]•2CH3OH was prepared by reaction of the equivalent molar of Schiff‐base ligand [H2L = (E)‐N′‐(2‐hydroxy‐4‐methoxybenzylidene)isonicotinohydrazide] and Bi (NO3)3•5H2O with the assistance of mannitol. The complex was structurally characterized by elemental analysis, spectroscopic methods (FT‐IR, MS, 1HNMR, and 13CNMR) and single crystal X‐ray diffraction. The molecular structure of the complex reveals that the ligand forms a 1:1 complex with bismuth(III) ion. It is composed of two 7‐coordinated bismuth(III) ions, two tetradentate O2N‐donor ligands, four nitrate ions, and three methanol molecules. The complex and its free ligand were evaluated against gram‐positive bacteria (Staphylococcus aureus, Bacillus subtilis) and gram‐negative bacteria (Escherichia coli, Pseudomonas aeruginosa). The complex was more active than the ligand against all bacterial strains. Their cytotoxic activity was also investigated against SNU‐16 cell. The complex is approximately three times more potent than the ligand, with the IC50 values 0.35 and 1.18 μM for the complex and its ligand, respectively.