Fluorescence and Absorption Titrations of Bio-relevant Imidazole Based Organometallic Pd(II) Complexes with DNA: Synthesis, Characterization, DNA Interaction, Antimicrobial, Cytotoxic and Molecular Docking Studies

Abstract

Organometallic Pd(II) complexes(4a–4f) of type Na[Pd(3n)Cl2]; where 3n = imidazole ligands (3a–3f), were synthesized. The complexes have been characterized by elemental analysis, thermogravimetric analysis, conductance measurement, mass spectrometry, UV–visible absorption spectroscopy, IR, 1H NMR, 13C APT NMR and Energy-dispersive X-ray spectroscopy. The compounds were screened for various biological activities such as nucleolytic, DNA binding, bacteriostatic (MIC) and cytotoxicity. DNA binding aptitude has been studied by UV–visible absorption titration, fluorescence spectroscopy, molecular modelling and viscosity measurement, which suggests Pd(II) complexes as DNA intercalating agents. Gibb’s free energy, enthalpy and entropy change parameters were evaluated for DNA–complex interaction by UV–visible absorption titration at different temperature, in which negative value of all the thermodynamic parameters suggests that the ligand–DNA complex is stabilized by hydrogen bonding and van der Waals forces. The gel electrophoresis of pUC19 DNA in presence of Pd(II) complexes showed the conversion of supercoiled DNA into open circular and linear form of DNA. Compounds were screened against different pathogens for evaluating their bacteriostatic activity in terms of MIC. In vitro cytotoxicity on Artemia cysts and in vivo cytotoxicity on S. pombe cells propose potent cytotoxic nature of Pd(II) complexes.