ИСТИНА

In this work macrobicyclic polyazaether (Cryptand 222, C18H36O6N2 ) was choosed as a ligand. Adsorption of cryptates of alcaline earth cations ( Ca2+, Sr2+,Ba2+ ) was investigated by impedance measurements on stationary Hg drop in 0.1M water solutions of corresponding chlorides. The obtained data point to a high surface activity of cryptates of two charged metal cations under study. These data are similar to ones for cryptates of alcaline metals cations, which have been investigated by us in previous works [1-3]. The dependencies of differential capacitance of electrical double layer on potential (C,E-curves) were measured for series of solutions with different concentrations of ligand. Mathematical treatment of experimental data was based on the model of two parallel capacitors supplemented by the Frumkin isotherm and was carried out by using the original regression analysis technique. Adsorption parameters of cryptates under study were calculated with use the all set of experimental data for each of systems. It’s shown that there is a satisfactorily coincidence between experimental capacitance curves and ones calculated with the parameters found. Essential distinctions of cryptates adsorption behaviour caused by distinctions in their structure and in the interaction with environment were established in spite of screening of included cations by organic ligand. Correlation between the adsorption behaviour of cryptates and their physical properties is supported by good agreement between dependences of adsorption parameters of cryptates and their stability constants (literature data) on radius of included cations. Evidently there is a deep mutual relationship between the structure of a complex and the regularities of its adsorption.