Synthesis, Characterization, Thermal degradation, X-Ray and DNA Binding Studies on Metal(II) and Mixed Metal Hydrazone Glyoxylate Dihydrates: A Typical One Step Aqueous Condensation Reaction

Abstract

Glyoxylic acid condenses with hydrazine hydrate in the presence of transition metal(II) ions viz., Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺ or Zn²⁺ resulting in the formation of metal(II) hydrazoneglyoxylate dihydrates. The compositions of these complexes, [M(OOCCH=NNH₂)₂(H₂O)₂] were assigned on the basis of hydrazine and metal analyses and further characterized by magnetic susceptibility measurements, UV-visible, infrared, ¹H and ¹³C NMR and D₂O exchange spectra, simultaneous TG-DTA analyses and X-ray powder diffraction techniques. The magnetic moments and UV-visible spectra indicate that these complexes are of high-spin octahedral geometry. The infrared spectra reveal the monodentate coordination of carboxylate ions and coordination of water molecules. The TG-DTA traces are in accordance with the formation of respective metal oxide as the end product after initial dehydration and further pyrolyses of the anhydrous complexes. The X-ray powder diffraction patterns indicate the isomorphism among the series of complexes. In these complexes the metal ions are octahedrally surrounded by two bidentate hydrazoneglyoxylate ions and two water molecules. The isomorphism among the series of complexes has been exploited in the preparation of mixed metal complexes. The mixed metal complex when heated to 300 °C in a pre-heated silica crucible undergoes autocatalytic decomposition to yield respective metal cobaltite, MCo₂O₄ as the final residue. The formation of the mixed metal complexes and metal cobaltites are confirmed by their infrared spectra and X-ray powder diffraction patterns. TG-DTA of the complexes also supports the formation of metal cobaltites. The particle size and SEM analyses of simple oxides and mixed metal oxides were carried out for further application of these metal cobaltites as catalysts. The interaction of Zn(II) complex with calf thymus DNA was investigated by absorption spectra. The DNA binding affinity of Zn(II) complex is 2.60 × 10⁴ M^-1 which reveals the strong binding affinity.