Thermal properties, geometrical structures, antimicrobial activity and DNA binding of supramolecular azo dye complexes

Abstract

Ru(III) complexes of 5-(4-derivative phenyl azo)-8-hydroxyquinoline (HLn) are prepared and characterized by elemental analyses, IR, UV–Visible spectra, 1H and 13C NMR spectra, mass spectra, X-ray diffraction analysis, conductivity measurements and magnetic susceptibility measurements as well as thermal analysis. The XRD patterns show that the ligand (HL3) has a polycrystalline nature and complex (2) is completely amorphous. The ligands act as a monobasic bidentate coordinating through CN and OH groups by replacement of a proton from the latter group. The molar conductivities show that the Ru(III) complexes are non-electrolyte in nature. The spectra show that all complexes are octahedral in which two chlorides are attached to the metal ion. The optimized bond lengths, bond angles and the calculated quantum chemical parameters for the ligands (HLn) and Ru(III) complexes are investigated. Molecular docking was used to predict the binding between azo dye ligands and the receptor of prostate cancer mutant 2q7k-hormone. The activation thermodynamic parameters, such as activation energy (Ea), enthalpy (ΔH⁎), entropy (ΔS⁎) and Gibbs free energy change of the decomposition (ΔG⁎) are calculated using Coats–Redfern and Horowitz–Metzger methods. The ligands (HLn) and Ru(III) complexes are screened for their antimicrobial activity against bacterial and fungal species. The tested complexes (1) and (2) have good antibacterial activity against Bacillus cereus and the tested ligands (HL2, HL3 and HL5) have good antifungal activity against Aspergillus niger and also HL5 showed against Alternaria alternata. The catalytic oxidation of cyclohexanol by [Ru(Ln)(AsPh3)2Cl2]·xH2O with periodic acid as co-oxidant is described. The Ru(III) complexes exhibited a catalytic activity for the oxidation of cyclohexanol to cyclohexanon.