Extraction and DFT study on the complexation of the cesium cation with dibenzo-21-crown-7

摘要

From extraction experiments and γ-activity measurements, the extraction constant corresponding to the equilibrium ? Cs~+ + A~- +cdotCs~+ n + A~- nb taking place in the two-phase water-nitrobenzene system (A~- = picrate, 1 = dibenzo-21-crown-7; aq = aqueous phase, nb = nitrobenzene phase) was evaluated as log K _(ex) (1?Cs~+, A~-) = 4.4 ± 0.1. Further, the stability constant of the 1?Cs~+ complex in nitrobenzene saturated with water was calculated for a temperature of 25 °C: log β_(nb) (1?Cs~+) = 6.3 ± 0.1. Finally, by using quantum mechanical DFT calculations, the most probable structure of the resulting cationic complex species 1?Cs~+ was solved.