Binding and photocleavage of a neutral nickel(II) bis(hydrogen pyridine-2,6-dicarboxylato) complex to DNA

A neutral nickel(II) bis(pyridine-2,6-dicarboxylato) complex, [Ni(Hdipic ^-) ₂] (Hdipic ^- = monohydricsalt of pyridine-2,6-dicarboxylic acid) was synthesized and its interaction with DNA were comprehensively investigated by electronic absorption spectroscopy, viscosity, fluorescence, melting temperature and gel electrophoresis measurements in this paper. Spectrophotometric titration suggested that the nickel(II) complex could intercalatively bind to DNA via the planar dipicolinic acid moiety with a moderate binding strength of 1.6 × 10 ⁴ M ^-1, and these results were further proved by the systematic studies of viscosity, ethidium bromide (EB) displacement and melting temperature experiments. Moreover, agarose gel electrophoresis assays showed that [Ni(Hdipic ^-) ₂] had obvious photocleavage property for the supercoiled plasmid pBR322 DNA under 302 nm irradiation for 30 min, which allow us to postulate the studied complex as a proper candidate for photocleavage reagent.