Synthesis, crystal structure and DNA cleavage activity of a novel Ni(II)–Cd(II) coordination polymer

A novel one-dimensional heterometallic complex, {Cd2[NiL]2(SCN)4(H2O)}n (1), has been synthesized and characterized by single-crystal X-ray analysis, where L is dianion of 2,3-dioxo-5,6,13,14-dibenzo-9,10-cyclohexyl-7,12-bis(ethoxycarbonyl)-1,4,8,11-tetraazacyclotetradeca-7,11-diene. The most striking feature of 1 is that in the structure there is one type of S–S bond (1.823(13) Å) formed by two thiocyanate groups which has not been reported to our knowledge. The DNA cleavage activity of 1 in the presence of H2O2 was compared with those of nickel(II) ion, cadmium(II) ion and corresponding mononuclear precursor NiL (2). The DNA cleavage kinetics was studied and the corresponding activation parameters of 1 were obtained.