Synthesis, characterisation and antimicrobial activity of bis(phthalazine-1-hydrazone)-2,6-diacetylpyridine and its complexes with CoIII, NiII, CuII and ZnII

Four new complex compounds of bis(phthalazine-1-hydrazone)-2,6-diacetylpyridine (Hz2DAP) ligand with NiII, CoIII, CuII and ZnII metal centres were synthesised and characterised by single-crystal X-ray diffraction and IR spectral data. The antimicrobial activity of Hz2DAP and the obtained complexes [Co(Hz2DAP-H)Cl2]·MeOH, [Ni(Hz2DAP-H)]Cl·MeOH, [Cu(Hz2DAP-H)Cl] and [Zn(Hz2DAP-2H)]·H2O were tested in vitro against selected Gram(−) and Gram(+) bacterial strains and fungi. The antimicrobial activity of the ligand is negligible, while its complexes with NiII, CoIII and CuII show considerable activity against Escherichia coli, Staphylococcus aureus and Micrococcus lysodeikticus. On the contrary, [Zn(Hz2DAP-2H)]·H2O promotes the growth of Candida albicans, while its antibacterial activity is negligible. On the basis of thermal data and those from coupled TG/MS measurements the decomposition mechanisms were determined and evaluated.

Complex compounds of NiII, CoIII, CuII with bis(phthalazine-1-hydrazone)-2,6-diacetylpyridine (Hz2DAP) ligand were synthesised. The coordination sphere of the metals is different in spite of the same synthetic procedure and same degree of protonation of the ligand, Hz2DAP-H. With ZnII a neutral complex [Zn(Hz2DAP-2H)]·H2O is obtained with double deprotonated ligand molecule.Figure optionsDownload as PowerPoint slide