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

•Triazine–nickel(II) complexes was synthesized and characterized.•The mechanism of DNA binding and photoluminescence of the complexes were determined.•Complexes sensitively detect DNA over a wide concentration range.•Complex 1 can serve as optical probes for anaerobic nonaqueous solutions.

We report here the synthesis of three new nickel(II) complexes: [Ni(PzTA)2CO3]·5H2O (PzTA = 2,4-diamino-6-(2′-pyrazin)-1,3,5-triazine) in 1, [NiQ(PyTA)(H2O)2]Cl·H2O (HQ = 8-hydroxyquinoline, PyTA = 2,4-diamino-6-(2′-pyridyl)-1,3,5-triazine) in 2, [NiQ(PzTA)(H2O)2]Cl·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 μg mL−1, 0.02–30 μg 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.

Graphical abstractComplex 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 μg mL−1, 0.02–30 μg mL−1, respectively. These findings indicate 1 may be a potential optical probe for oxygen-free environments in nonaqueous form, while 2 and 3 were DNA-targeted probes.Figure optionsDownload full-size imageDownload as PowerPoint slide