Cu(I)-phospine complex exhibits temperature-dependent DNA intercalative binding: Insights from spectroscopic and molecular modeling studies

Abstract

The synthesis and characterization of a Cu(I) phosphine complex, as well as spectroscopic and simulation studies of its interaction with the DNA helix, are described. Based on X-ray single-crystal diffraction data, the monoclinic phase [Cu(PPh3)(L)(I)], L = 2-((pyridin-2-ylmethylene)amino)isoindoline-1,3-dione, with a tetrahedral molecular geometry was synthesised. The experimental results suggested that the complex could target DNA with a high affinity via an intercalation binding mode. The Stern–Volmer analysis based on fluorimetry approved that raising the temperature from 283 to 293 K causes the Ke to increase, confirmed a dynamic mechanism in the interaction while a further increase of temperature to 303 K, causes the opposite consequence which confirmed a static nature for the interaction at the high range of temperatures. Furthermore, a concluded positive cooperativeness at ambient temperature would be particularly important to achieve a significant impact of the complex on DNA strands even at low complex concentrations. According to competitive fluorescence tests the complex interacts with DNA at intercalation binding sites on DNA. The resulting entropy and enthalpy shifts identify the van der Waals forces as the interaction's primary binding mechanism. Docking study confirmed the insertion of aromatic ring into the DNA double helix.