DNA-binding and hydrolytic cleavage promoted by tetraazamacycle La(III) and Ce(III) complexes

In this work, 5,7,7,12,14,14-hexamethyl-1,4,8,11- tetraazacyclotetradecane (teta) and its two lanthanide(III) complexes, Ln(teta)(NO3)3·(Ln = La(III) and Ce(III)), have been synthesized and characterized. The interactions between pUC19 DNA and the two trivalent lanthanide complexes have been studied by UV–Vis absorption spectroscopy, fluorescence spectroscopy, and cyclic voltammetry. The results suggest that these two rare earth metal complexes can bind to plasmid DNA pUC19 non-intercalatively, and an exterior electrostatic binding is the preferred mode. And, both of these two lanthanide(III) complexes have been found to be efficient in DNA cleavage via hydrolytic pathway under very mild conditions with complex concentration of 5 × 10−3 mol L−1 at pH 7.34, 37 °C and 3 h, which that suggest these two complexes were potent agents for supercoiled pUC19 DNA cleavage hydrolytically. And, the title complexes showed efficient cleavage function on pUC19 DNA was ascribed to the special properties of trivalent lanthanide ions and the relatively small space hindrance provided by the ligand with its boat form isomer in the water medium.