Synthesis, spectral and biological studies of Mn(II), Ni(II), Cu(II), and Zn(II) complexes with a tetradentate Schiff base ligand. Complexation studies and the determination of stability constants (Ke)

The complexes Mn(II), Ni(II), Cu(II) and Zn(H) ions with a N2O2 Schiff base derived from 1,4-diaminobutane and salicylaldehyde, N,N'-bis(salicylidene) -1,4-diaminobutane (LH2), have been prepared and characterized by elemental analyses, molar conductivities, spectral (IR, NMR, visible, UV) and magnet ic moment measurements. Stability constants were measured by means of a con ductometric method. Furthermore, the stability constants for complexation b etween ZnCl2, Cu(NO3)(2) and AgNO3 salts and the ligand in 80% dioxane-wate r and pure methanol were determined by conductance measurements. The magnit udes of these ion association constants are related to the nature of the so lvation of the cation and the complexed cation. The mobilities of the compl exes are also dependent, in part, upon solvation effects. The complexes Mn( II), Ni(II), Cu(II) and Zn(II) ions with the Schiff base have been evaluate d for their antibacterial activity against rec(-)and rec(+) stains of Bacil lus subtilis.