Solvent isotope effects on the complexation and exchange kinetics of Tl(I), K+ and Na+ with 18-crown-6 by competitive NMR spectroscopy: Competition between homo- and heterobimolecular cations exchange

► Thermodynamic and exchange kinetics of complexation has been studied by thallium NMR spectroscopy. ► Complexation/decomplexation process of Tl+, K+ and Na+ by 18-crown-6 has been studied in H2O and D2O. ► In the presence of competitor cations, exchange mechanism is homobimolecular at low concentrations of the ligand. ► At higher concentrations, a heterobimolecular cation exchange is the predominant mechanism.