Synthesis, structural characterization and biological activity of a trinuclear zinc(II) complex: DNA interaction study and antimicrobial activity

A trinuclear zinc(II) complex [Zn 3 L 2 (μ-O 2 CCH 3 ) 2 (H 2 O) 2 ]·H 2 O·2CH 3 OH ( 1 ) was synthesized from an in situ reaction between zinc acetate and a Schiff base ligand (H 2 L = 2-((2-hydroxyphenylimino)methyl)-6-methoxyphenol). The ligand was prepared by (1:1) condensation of ortho -vanillin and ortho -aminophenol. The ligand and zinc(II) complex were characterized by elemental analysis, Fourier Transform Infrared (FTIR), 1 H-Nuclear Magnetic Resonance (NMR), UV-Vis spectroscopy, Powder X-ray Diffraction (PXRD) and thermogravimetric analysis. 1 crystallizes in P-1 space group with a = 11.9241(3) Å, b = 12.19746 Å, c = 20.47784 Å with unit cell volume is 2674.440 (Å) 3 . Binding property of the complex with calf thymus DNA (CT-DNA) has been investigated using absorption and emission studies. Thermal melting and viscosity experiments were further performed to determine the mode of binding of 1 with CT-DNA. Spectroscopic and viscosity investigations revealed an intercalative binding mode of 1 with CT-DNA. The ligand and its zinc complex were screened for their biological activity against bacterial species and fungi. Activity data show that the metal complex has more antibacterial and antifungal activity than the parent Schiff base ligand and against those bacterial or fungi species. Graphical Abstract A trinuclear Zinc(II) complex, [Zn 3 L 2 (μ-O 2 CCH 3 ) 2 (H 2 O) 2 ]·H 2 O·2CH 3 OH ( 1 ) of a (N,O)-donor Schiff base ligand has been synthesized and structurally characterized. The Zn(II) complex interacts significantly with CT-DNA and spectroscopic and viscosity investigations revealed an intercalative binding mode of 1 with DNA. The biological activity of the zinc(II) complex against different bacterial and fungal organisms is very promising.