Spectroscopic, thermal and biocidal studies on Mn(II), Co(II), Ni(II) and Cu(II) complexes of tridentate ligand having semicarbazone moieties

Abstract

Mn(II), Co(II), Ni(II) and Cu(II) complexes having the general composition M(L)2X2 [where L = 2-pyridinecarboxaldehyde semicarbazone, M = Mn(II), Co(II), Ni(II) and Cu(II), X = Cl− and NO3 −] have been synthesized. All the synthesized compounds were identified and confirmed by elemental analysis, molar conductance, magnetic susceptibility measurements, mass, IR, EPR, electronic spectral studies and thermogravimetric analysis (TG). The Molar conductance measurements of the complexes lie in the range 209–228 Ω1 cm−1 mol−1 indicating that the complexes are 1:2 electrolytic in nature. Thus the complexes may be formulated as [M(L)2]X2. The magnetic moment measurements of the complexes indicate that all the complexes are in high-spin state. On the basis of spectral studies an octahedral geometry has been assigned for Mn(II), Co(II) and Ni(II) complexes whereas tetragonal geometry for Cu(II) complexes. The thermal studies suggested that the complexes are more stable compared with free ligand. This fact was supported by calculating the thermodynamic parameters by using Horowitz–Metzger (HM) and Coats–Redfern (CR) equations. The free ligand and its metal complexes were also evaluated against the growth of phytopathogenic fungi and bacteria in vitro.