COMPLEXATION OF COPPER(II) IONS WITH AMPICILLIN .1. SPECTROSCOPIC ANDELECTROCHEMICAL INVESTIGATION OF INTERACTIONS UNDER EQUILIBRIUM CONDITIONS

The interactions in the copper(II) ion-ampicillin system were studied by the use of electrochemical and spectroscopic methods under equilibr ium conditions. In the system, two aqueous soluble coordination compou nds with molar compositions of 1:1 and 1:3 and a precipitate with mola r ratio 1:2 were formed. Copper(II) ions promoted the hydrolysis of th e beta-lactam group of ampicillin, therefore the ampicillin ligand in the compounds was transformed into ampicilloic acid as a result of hyd rolysis. The soluble compounds are relatively stable, log K(st) being 5.0 and 14.5, respectively. The solubility of the precipitate was cons tant over a broad pH range (4-10) and the solubility product constant K(sp) of the compound was evaluated as 2.7 x 10(-11) under equilibrium conditions.