Crystal structure, DNA-binding, and fluorescence properties of cadmium(II) complex with N-(2-acetic acid)salicyloyl hydrazone and imidazole

A novel cadmium(II) complex with N-(2-acetic acid)salicyloyl hydrazone (C(9)H(8)N(2)O(4), H(3)L) and imidazole (Im) was prepared and characterized. The crystal structures of ligand H(3)L and cadmium(II) complex were determined by X-ray single-crystal diffractometry. The complex consists of three binuclear neutral unattached units. One of Cd(2+) is six-coordinated by the carboxylic O atom, acylic O atom, and azomethinic N atom of one ligand H(3)L (HL(2-) form), carboxylic O atom from the other ligand H(3)L by the mu(2)-bridging form and N atoms from two imidazoles, but the other five Cd(2+) ions all are seven-coordinated more than an O atom from coordinated water molecule compared with six-coordinated Cd(2+). HL(2-) acts as tridentate ligand forming two stable five-numbered rings and sharing one side in the keto form for each ligand, and the carboxyl groups of two HL(2-) ligands are coordinated via the mu(2)-bridging form. The coordination polyhedron around Cd(2+) was described as a octahedron or pentagonal bipyramidal. The inter- and intramolecular hydrogen bonds resulted in a three- dimensional network and provided extrastability for the structure. The complex exhibits good fluorescence properties. The complex was also searched for the interaction with CT-DNA by electronic absorption titration and emission titration. The results show that the complex is bound to calf thymus DNA mainly by intercalation.