Synthesis and characterization of a tetraaza macrocyclic ligand and its Cobalt(II), Nickel(II) and Copper(II) complexes

Co(II), Ni(II), and Cu(II) complexes with a tetradentate nitrogen donor [N4] macrocyclic ligand, viz 1,5,8,13-tetraaza-2,9-dimethyl-4,11- diphenylcyclotetradeca-2,4,4,11-tetraene were synthesized. Their structures were determined based on elemental analyses; molar conductance and magnetic susceptibility measurements; and IR, 1H-NMR (ligand), and electronic spectral studies. Based on analytical and molar conductance data, the complexes may be formulated as [M(L)Cl2] and [M?(L)]Cl2 [where M = Co(II) and Cu(II), and M? = Ni(II)] due to their non-electrolytic and 1:2 electrolytic nature. Based on spectral studies, an octahedral geometry was assigned for the Co(II) complex, whereas square-planar and tetragonal geometry were proposed for the Ni(II) and Cu(II) complexes, respectively. The synthesized ligand and its complexes were screened for fungicidal activity against two pathogenic fungi (i.e., Fusarium. moniliformae and Rhizoctonia solani) to assess their growth inhibiting potential.

Spectroscopic, thermal and antibacterial studies on Mn(II) and Co(II) complexes derived from thiosemicarbazone

Mn(II) and Co(II) complexes having the general composition [M(L)2X2] (where L = 2-pyridinecarboxaldehyde thiosemicarbazone, M = Mn(II) and Co(II), X = Cl- and - NO3 ) were synthesized. All the metal complexes were characterized by elemental analysis, molar conductance, magnetic susceptibility measurements, mass, IR, EPR, electronic spectral studies and thermogravimetric analysis (TG). Based on the spectral studies, an octahedral geometry was assigned for all the complexes. Thermal studies of the compounds suggest that the complexes are more stable than the free ligand. This fact was supported by the kinetic parameters calculated using the Horowitz-Metzger (H-M) and Coats-Redfern (C-R) equations. The antibacterial properties of the ligand and its metal complexes were also examined and it was observed that the complexes are more potent bactericides than the free ligand.