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

Abstract

A novel cadmium(II) complex with N-(2-acetic acid)salicyloyl hydrazone (C9H8N2O4, H3L) and imidazole (Im) was prepared and characterized. The crystal structures of ligand H3L and cadmium(II) complex were determined by X-ray single-crystal diffractometry. The complex consists of three binuclear neutral unattached units. One of Cd2+ is six-coordinated by the carboxylic O atom, acylic O atom, and azomethinic N atom of one ligand H3L (HL2− form), carboxylic O atom from the other ligand H3L by the μ2-bridging form and N atoms from two imidazoles, but the other five Cd2+ ions all are seven-coordinated more than an O atom from coordinated water molecule compared with six-coordinated Cd2+. HL2− 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 HL2− ligands are coordinated via the μ2-bridging form. The coordination polyhedron around Cd2+ 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.