Transition Metal Complexes of (E)-N’-(4-cyanobenzylidene)nicotinohydrazide): Synthesis, Structural and Anti-Mycobacterial Activity Study

Abstract

A B S T R A C T One step condensation of nicotinic acid hydrazide and 4-cyanobenzaldehyde formed a bidentate acylhydrazone ligand (HL 5 ). The acylhydrazone was characterized by ESI mass spectrometer, CHN analyzer, IR spectrometer, 1 H-NMR, 13 C-NMR and 2D NMR (COSY and HSQC). Thereafter, Mn(II), Mo(V), Fe(II), Cu(II) and Zn(II) complexes of the acylhydrazone ligand were synthesized and characterized based on conductivity measurements, melting point determination, CHN analysis, AAS, magnetic measurement, UV/Visible study, IR spectroscopy, ESR and TGA/DTA studies. The information obtained corroborated results from powder X-ray analysis to arrive at the model structures for the complexes. In vitro antimycobacterial properties of the compounds were evaluated against Mycobacterium tuberculosis H37Rv by using micro-diluted method. The result obtained revealed that HL 5 , Mn(II), Mo(V), Cu(II) and Zn(II) complexes exhibited promising antitubercular activity. Zn(II) complex had the highest MIC value of 0.62 μg MLG 1 , while Fe(II) complex exhibited the lowest MIC value of 1.15 μg MLG 1 . However, the result of cytotoxicity study indicated that acylhydrazone and Zn(II) complex with IC50 of 2.17 and 1.72 μM, respectively were not toxic compared to isoniazid. Mn(II) complex was however found to be the most toxic.