SYNTHESIS AND SPECTRAL CHARACTERIZATION OF Co(II), Ni(II) AND Cu(II) COMPLEXES OF AMOXICILLIN

Abstract

Metal (II) complexes of amoxicillin were synthesized and their aqueous solubility properties, stabilities, antimicrobial properties were evaluated. The mixed ligand complexes of Co(II), Ni(II) and Cu(II) containing an amoxicillin (AMX) as the primary lagnd and water (L) as the secondary ligand have been prepared. Spectroscopic and physicochemical techniques, namely, UV–visible, Fourier-transform infrared spectroscopy, molar conductance, together with elemental analysis was used to characterize the synthesized complexes. Based on these studies, the general formulae [M(AMX)2(L)2]X2 where AMX=Amoxicillin; L=H2O; M=Co(II), Ni(II) and Cu(II); X=Cl- and 1/2SO42-] were proposed for the complexes. The complexes are found to be insoluble in common organic solvents. The molar conductance values suggest the non-electrolytic nature of the complexes. The IR spectral data revealed the primary ligand (AMX) to be bidentate coordinating to metal through carboxylate and lactamic carbonyl. The absence of 𝜐(CO) (𝛽-lactame) band at 1771 cm−1 and the appearance of the band at 1650–1600 cm−1 in all complexes revealed that enolization takes place before coordination of the ligand to the metal ions. The ultraviolet (UV) absorption peaks at 220- 260 nm for AMX ligand are assigned to n-σ* and π-π* intraligand transitions. From chemical and spectral data (molar absorptivity and electronic transition), octahedral geometries were assigned to [Co(AMX)2(H2O)2]Cl2, [Ni(AMX)2(H2O)2]SO42- and [Cu(AMX)2(H2O)2]SO42- respectively with configurations existing in a 2:1:2 molar ratio of primary ligand: metal: secondary ligand.