Complexation of Thallium(I) with Adenosine 5′-Monophosphate in Aqueous Methanol Solutions

Abstract

The formation constants of the species formed in the systems H⁺ + thallium(I) + AMP and H⁺ + AMP have been determined in aqueous solutions of methanol at 25°C and constant ionic strength 0.1 mol dm^-3 sodium perchlorate, using spectrophotometric and potentiometric techniques. Thallium(I) forms two mononuclear 1:1 complexes with AMP of the type TlHL and TlL^- in the pH range of study (1 - 11), where L^2- represents the fully dissociated ligand. The formation constants in various media were analyzed in terms of Kamlet and Taft's parameters. Single-parameter correlation of the formation constants, β₁₁₁ and β₁₀₁, versus α (hydrogen-bond donor acidity), β (hydrogen-bond accepter basicity), and for π^* (dipolarity/polarizability) are relatively poor in all solutions, but multi-parameter correlation represents significant improvement with regard to the single-parameter models. Finally, the results are discussed in terms of the effect of the solvent on complexation.