Experimental and theoretical study on the complexation of the cesium cation with dibenzo-30-crown-10

From extraction experiments and γ-activity measurements, the extraction constant corresponding to the equilibrium Cs+ (aq) + A- (aq) + 1(nb) ↔ 1 Cs+(nb) + A-(nb) taking place in the two-phase water-nitrobenzene system (A- = picrate, 1 = dibenzo-30-crown-10; aq aqueous phase, nb = nitrobenzene phase) was evaluated as log Kex (1 Cs+, A-) 4.0 ± 0.1. Further, the stability constant of the 1 Cs+ complex in nitrobenzene saturated with water was calculated for a temperature of 25 deg C: log β nb (1 Cs+) = 5.9 ± 0.1. Finally, by using quantum-mechanical DFT calculations, the most probable structure of the resulting cationic complex species 1 Cs+ was derived. (author)