Synthesis, structural identification, DNA interaction and biological studies of divalent Mn, Co and Ni chelates of 3-amino-5-mercapto-1,2,4-triazole azo ligand

New Mn (II), Co (II) and Ni (II) azo chelates of 3-amino-5-mercapto-1,2,4-triazole have been designed and obtained. The structures of these newly isolated complexes were assigned according to elemental, thermal analyses, spectral measurements, conductivity and magnetic moment. The metal complexes were predicted to be not electrolytic from the measured molar conductance values. The magnetic moment and UV-Vis spectral data denoted the formation of octahedral geometries for Mn (II), Co (II) and Ni (II) complexes. Thermal properties and decomposition kinetics of the metal chelates are investigated using Coats-Redfern method. The kinetic parameters like activation energy (E*), pre-exponential factor (A) and entropy of activation (Delta S*) were quantified. The geometry of the metal complexes is optimized with the help of molecular modeling. The interaction of metal chelates with calf thymus DNA (CT-DNA) was evaluated via UV-Vis absorption and viscosity measurements. The obtained data elucidated that the Ni (II) chelate interact with DNA by groove binding while partial intercalative binding mode have been predicted for Mn (II) and Co (II) chelates. The estimated binding constants for the DNA-complexes are 3.85 +/- 0.03 x 10(4), 1.03 +/- 0.2 x 10(5) and 2.81 +/- 0.02 x 10(5) M-1, for Mn (II), Co (II) and Ni (II) azo chelates, successively. Also, the synthesized complexes were tested for their in-vitro antimicrobial and anticancer efficacy.