Low DNA and high BSA binding affinity of cationic ruthenium(II) organometallic featuring pyridine and 2’-hydroxychalcone ligands

Abstract The chiral-at-metal, piano-stool ruthenium(II) racemic organometallic [Ru(cymene)(chalconato)(pyridine)]PF6 was prepared by a multistep solution synthesis and its molecular and crystal structure was determined by single crystal X-ray diffraction. The compound crystallizes in a centrosymmetric triclinic P-1 space group with two molecules of opposite chirality within the asymmetric unit. Ruthenium is embedded in an octahedral half-sandwich coordination environment with four different donors, which generates the chirality of the metal centre. The formation of the organometallic was monitored ex-situ by infrared spectroscopy. The pyridine coordination to Ru(II) was particularly analysed to find its characteristic marker bands. The complex was also characterized by elemental analysis and NMR spectroscopy in solution. Its interaction with CT DNA and bovine serum albumin (BSA) was investigated by electron spectroscopy and spectrofluorimetry. The organometallic binds to DNA predominantly by electrostatic forces with low Kb value. On the contrary, its high affinity for BSA was confirmed by strong fluorescence quenching. The synchronous emission spectra revealed that the microenvironment of tryptophan is more affected compared to the environment of tyrosine.