Study of binary complexes of nickel(II), copper(II), and vanadium(V) with acetazolamide in aqueous medium by voltammetry

The voltammetric behaviour of acetazolamide, the systemic carbonic anhydrase inhibitor, in the presence of some metal ions (Cu(II), Ni(II), and V(V)) were investigated using square-wave and cyclic voltammetry in physiological pH (pH 7.4). Square-wave voltammogram of acetazolamide in the absence of metal ions gave only 1 reduction peak at -1.65 V attributed to a catalytic hydrogen peak. Three reversible peaks at -0.068, -0.262, and -0.434 V were observed for the solutions containing both copper(II) ions and acetazolamide in the SWV. The peak at -0.434 V was attributed to Cu(II)-acetazolamide complex. In the presence of acetazolamide, copper-acetazolamide complex formation was proved by a reversible peak with 2 electron transfers at -0.450 V. Complex formation of an adduct of trioxovanadate(V) with acetazolamide onto dropping mercury electrode was followed by a reduction peak at -0.480 V. Ni(II)-acetazolamide complex was observed to reduce at the more positive potential (-0.830 V) than that of the hydrated Ni(II) ions (-1.200 V) implying that acetazolamide is a catalyst for Ni(II) reduction at a mercury electrode. The UV-vis spectra of all the acetazolamide complexes were also discussed.