Synthesis, Characterization and Anti – Plasmodial Activities of Bis – 4 – Hydoxybenzylidene – N, N – Ethylenediamine Complexes of Cu(II), Co(II) and Ni(II) Ions

Abstract

Three metal complexes have been synthesized from Ni(II), Cu(II) and Co(II) chlorides with ligand bis-4- hydroxylbenzylidine-N, N-ethylenediamine. using the microwave assisted method and were characterized using electronic spectra (ultra-violet -visible spectroscopy), Fourier Transformed infrared spectra (vibrational spectroscopy), molar conductivity measurement, magnetic susceptibility and solubility test. The uv-visible data showed absorption peak for the ligand at 296nm, 298nm for the Cu complex,293nm for the cobalt complex which can be attributed to an n-π* transition and octahedral geometry while the Nickel complex showed absorption band at 308nm which corresponds to π -π* transition and octahedral geometry. The magnetic susceptibility data showed values of 1.5-1.7BM in the complexes which confirms octahedral geometry, the FTIR data showed that the Schiff base ligand acted in bidentate fashion to the central metal with coordination involving the azomethine nitrogen atoms with vibrations at 808.8 -887.1cm^-1 that is v(M-N). A blue shift was observed from the free ligand at 1590.3cm^-1 which is due to v(C=N) to 1543.3cm^-1 and 1500.2 cm^-1 in the BHBED-Cu and BHBED-Co complexes and a red shift to 1654.9 cm^-1 in the BHBED-Ni complex. Vibrations at 700.7-756.6 cm-1 in the metal complexes can be ascribe to M-O. The metal complexes and ligand were insoluble in distilled water; the complexes were completely soluble in DMSO but were insoluble in n-hexane. The conductance data showed that the ligand is non-electrolytic but the metal complexes are electrolytic. The
Schiff base and their metal complexes were also screened for their antimalarial activity against plasmodium falciparum, the complexes showed better antiplasmodium activity than Schiff base, with the BHBED-Cu and BHBED-Ni showing 100 and 99 % activity.