STUDIES OF VALEROHYDROXAMIC AND ' ISOVALEROHYDROXAMIC ACIDS AND OF THEIR COMPLEXES WITH SOME BIOLOGICALY IMPORTANT METAL IONS

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Valerohydroxamic and Isovalerohydroxamic acids were synthesised and recrystallised from ethylacetate. They were characterised by melting point, pka and spectral (IR NMR) studies. Their melting points are 77.78°C and 76.77°C for valerohydroxamic acid and isovalerohydroxamic acid respectively and their pka values at 0.1mol dm-3 at 28°C are 9.50+0.01 and 9.51+0.01 for valerohydroxamic acid and isovalerohydroxamic acid respectively.

The IR and NMR (1H and 13C) for both valerohydroxamic and Isovalerohyrdoxamic acids are in accord with the theoretical prediction and observable patterns of the reported alkylhydroxamic acids. Their complexes with the following metal ions; Al3+, Co3+, Co2+, Cu2+, Fe3+, Mn2+, V02+, and Zn2+, were prepared in good yield. The complexes were characterised using solution, conductivity and spectra (IR, electrical) studies. Their relatively low melting points in the range of 142 - 215°C is suggestive of a weak interaction between the species. The complexes are soluble in almost all the

polar organic solvents in which they were tested with the exception of their Co3+ and Cu2+ complexes which are only sparingly soluble

and their low conductivity values in the range of 0.002 - 0.025 Scm2 mol-1 implies that they are non electrolyte in ethanol. The absence of isosbestic points and the shape of the graphical r-ank matrix analysis indicate that the complexes are made of single species in solution. The Job's plot for the systems indicate a 1:2 and 1:3 metal-ligand ratio for the divalent and trivalent metal ions respectively. The IR studies of the complexes show chelation by

coordination via the ketonic oxygen and the oxygen of the NHO-. The electronic spectra of the transition metal complexes indicate octahedral coordination for CoH, Co2+, Fe3+, Cu2+, Ni2+ and V02+ complexes, while the Cu2+ complexes may possibly be of a square planar coordination. The microbial activity of the ligands and their metal complexes were tested against the following microbes; Sa, Es, Ps, Bs and Ca.

Valerohydroxamic acid was positive against Es and Bs, while Isovalerohydroxamic acid was negative against all the micr-obes. The Co2+ - Valerohydroxamate was positive against Sa and Ps, while Co2+- Isovalerohydroxamate tested positive against Sa only. The Co3+- Isovalerohydroxamate was positive against Sa, Ps and Ca, while the Co3+ - Valerohydroxamate tested positive against Sa and Bs and Fe3+ - Valerohydroxamate was positive against Sa and Ca. All activity were low at a dose concentration of 1000�L9/ml.

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STUDIES OF VALEROHYDROXAMIC AND ' ISOVALEROHYDROXAMIC ACIDS AND OF THEIR COMPLEXES WITH SOME BIOLOGICALY IMPORTANT METAL IONS

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