Synthesis, crystal structures, photoluminescence properties and DNA binding of triazine-nickel(II) complexes for DNA detection

We report here the synthesis of three new nickel(II) complexes: [Ni(PzTA)(2)CO3]center dot 5H(2)O (PzTA = 2,4-diamino-6-(2'-pyrazin)-1,3,5-triazine) in 1, [NiQ(PyTA)(H2O)(2)]Cl center dot H2O (HQ = 8-hydroxyquinoline, PyTA = 2,4-diamino-6-(2'-pyridyl)-1,3,5-triazine) in 2, [NiQ(PzTA)(H2O)(2)]Cl center dot H2O in 3, and they were characterized by UV spectroscopy, elemental analysis, molar conductivity and X-ray single crystal diffraction. Binding of the complexes to ct-DNA was investigated with electronic spectroscopy, ethidium bromide displacement from DNA, viscometry and cyclic voltammetry. The results depicted the DNA binding mode of the three complexes was intercalation, and complex 1 together with external static-electricity. Moreover, the three complexes also presented potential anti-oxidant activity. Interestingly, we found 1 was sensitive to oxygen and to the polarity of nonaqueous solvents in fluorescence spectroscopy. Fluorescence of 2 and 3 is weak in neutral aqueous solvents, but is greatly enhanced by addition of ct-DNA Thus, 2 and 3 can be used to DNA detection as DNA fluorescence probes with a LOD of 1.61 ng mL(-1), 4.90 ng mL(-1) for the relative wide linear range of 0.01-20 mu g mL(-1), 0.02-30 mu g mL(-1), respectively. These findings indicate that 1 may be a potential optical probe for oxygen-free environments in nonaqueous form, while 2 and 3 were DNA-targeted probes. (C) 2015 Elsevier B.V. All rights reserved.