Complex Formation in Systems Cobalt(II)-Glycine-Beta-Lactam Antibiotics

Complex formation in solutions containing cations Co²⁺, glycine anions (Gly), and β-lactam antibiotics—ampicillin (Amp), amoxicillin (Axn), and cefalexin (Cpx)—has been investigated using pH-metric titration at 20°C and ionic force strength of 0.1 (KNO₃). In a weakly alkaline medium, mixed-ligand complexes CoGlyAmp], CoGlyAxn], and CoGlyCpx], which are in equilibrium with CoGly]⁺ complexes, are formed in the systems. The formation constants of complexes have been determined. The distribution diagrams of complex cobalt(II) species depending on pH have been constructed.