The synthesis of two molecules, B1 and B2, based on elements of norbadione A, the natural Cs+ chelator in mushrooms, associated, in the case of B2, with an 18-crown-6 ether is reported. Thermodynamic and kinetic analyses performed in water, ethanol and ethanol/water 9/1 v/v (M1) show in M1 and ethanol that B1 and B2 form stable complexes with Na+, K+ and Cs+. Affinity constants, measured spectrophotometrically in ethanol and ...