Synthesis,structural characterization and molecular modelling of bidentate azo dye metal complexes: DNA interaction to antimicrobial and anticancer activities

A novel azo dye ligand, namely 1‐[(5‐mercapto‐1H‐1,2,4‐triazole‐3‐yl)diazenyl]naphthalen‐2‐ol (HL), was synthesized. Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺ and UO₂²⁺ complexes were also prepared by the treatment of HL with Mn(CH₃COO)₂?4H₂O, Co(CH₃COO)₂?4H₂O, Ni(CH₃COO)₂?4H₂O, Cu(CH₃COO)₂?H₂O, CuCl₂?2H₂O, Cu(NO₃)₂?6H₂O and UO₂(NO₃)₂?6H₂O. The structures of these metal chelates were confirmed using elemental, spectral, magnetic moment, molar conductance and thermal analyses. The analytical data confirmed the formation of the chelates in 1:1 (metal‐to‐ligand) ratio having the formula [ML(H₂O)X]Y?H₂O, where M is Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺ or UO₂²⁺; X is Cl^?, NO₃^? or CH₃COO^?; and Y is H₂O. The azo compound acts in a monobasic bidentate manner via the nitrogen and oxygen atoms of azo and hydroxyl groups, respectively. All complexes were found to have tetrahedral structures, except the UO₂²⁺ complex that showed octahedral geometry. The mode of interaction between the synthesized complexes and calf thymus DNA was explored by the aid of absorption spectroscopy and viscosity measurements. The azo dye and its chelates were evaluated against the growth of various bacterial and fungal strains (Escherichia coli, Staphylococcus aureus, Aspergillus flavus and Candida albicans) with insight gained into the effect of type of metal centre, type of coordinated anion and position of the metal in the periodic table on the activity of the complexes. The geometric structure of the complexes was optimized using molecular modelling. The in vitro cytotoxicity of the synthesized compounds was tested against HEPG2 cell line.