A mononuclear zinc(<sc>ii</sc>) complex and a tetranuclear copper(<sc>ii</sc>) azametallacoronate with (E)-2-((2-(quinazolin-4-yl)hydrazono)methyl)phenol: structure and biological activity

A quinazoline derivative containing a properly situated o-phenol ring, namely (E)-2-((2-(quinazolin-4-yl)hydrazono)methyl)phenol (H2L), was synthesized in order to investigate the ability of this novel ligand for metal complexation. The interaction of deprotonated HL- with Zn(ii) resulted in the mononuclear complex [Zn(HL)2]<middle dot>1.5CH3OH<middle dot>H2O (complex 1). When doubly deprotonated ligand L-2 reacted with Cu(ii), the tetranuclear complex [Cu4(L)4(DMF)4]<middle dot>8H2O (complex 2) was isolated, which can be described as an azametallacoronate compound. All three compounds (H2L and complexes 1 and 2) were characterized by spectroscopic techniques and single-crystal X-ray crystallography. The biological profile of the compounds was evaluated in regard to their affinity for calf-thymus DNA, the ability to cleave supercoiled circular pBR322 plasmid DNA in the absence or presence of irradiation of various wavelengths (UVA, UVB and visible light), their binding with bovine serum albumin and their capacity to scavenge 1,1-diphenyl-picrylhydrazyl and 2,2 '-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) radicals and to reduce H2O2. The compounds can bind tightly to calf-thymus DNA via intercalation, and do not induce notable cleavage of plasmid DNA. They can bind tightly and reversibly to the albumin and have shown moderate antioxidant activity.