Multi-analytical studies about physico-chemical properties of Ni(II)-vitamin B6 coordination compounds and their CT-DNA interactions

Two coordination compounds and their structural characterization of [Ni(PM)2]Cl2 and [Ni(PL)2]Cl2 have been studied. Pyridoxamine (PM) and pyridoxal (PL) denote individual vitamers of vitamin B6 and both demonstrated bidentate nature inside the complexes. The acid-base behavior of the mentioned complexes and their possible interactions with biomolecules in solutions have been never reported. Here, UV-spectroscopic, potentiometric, cyclic voltammetric studies have been carried out on the interaction of the Ni(II)-vitamer complexes with protons as well as with calf thymus-DNA (CT-DNA) in aqueous medium. The acidity constants values of coordination compounds studied have been determined and compared. The potentiometric and pHmetric-spectrophotometric microtitrations were carried out at the same conditions of temperature and pH range, 25°C and 1.72–11.68, respectively. The procedural decomposition temperatures of the complexes were given and considered in relation to the structures of the examined compounds to complete the structural description of [Ni(PM)2]Cl2 and [Ni(PL)2]Cl2. The CT-DNA binding potential of Ni(II) complexes was carried out by absorption spectroscopy and cyclic voltammetry methods. Mechanism investigation has demonstrated that examined compounds could interact to CT-DNA by grooving binding mode, which was stabilized by hydrogen bond and van der Waals forces.