Protonation Equilibria of Quinolone Antibacterials

摘要: The acid–base properties of seven antibacterial 7-piperazinyl fluoroquinolone derivatives were studied by potentiometry and UV NMR spectroscopy. These molecules contain two proton-binding sites similar basicity, namely, the piperazine amino carboxylate groups, as proven 1H basicities are quantitated at molecular level in terms macroconstants, also submolecular microconstants. microconstants then used to calculate concentration positive, zwitterionic, neutral, negatively charged species (microspeciation). zwitterionic forms always predominate over their neutral protonation isomers, but zwitterionic:neutral ratio is considerably different for examined derivatives.