The transfer of sodium and potassium ions facilitated by dibenzo-15-crown-5 (DB15C5) has been studied at the micro-water/l,2-dichloroethane (water/DCE) interface supported at the tip of a micropipette. Cyclic volt-amm...The transfer of sodium and potassium ions facilitated by dibenzo-15-crown-5 (DB15C5) has been studied at the micro-water/l,2-dichloroethane (water/DCE) interface supported at the tip of a micropipette. Cyclic volt-ammetric measurements were performed in two limiting conditions: the bulk concentration of Na+ or K+ in the aqueous phase is much higher than that of DB15C5 in the organic phase (DB15C5 diffusion controlled process) and the reverse condition (metal ion diffusion controlled process). The mechanisms of the facilitated Na+ transfer by DB15C5 are both transfer by interfacial complexation (TIC) with 1:1 stoichiometry under these two conditions, and the corresponding association constants were determined at log β1 = 8.97±0.05 or log β1 = 8.63±0.03. However, the transfers of K+ facilitated by DB15C5 show different behavior. In the former case it is a TIC process and its stoichiometry is 1:2, whereas in the latter case two peaks during the forward scan were observed, the first of which was展开更多
基金This work was supported by the Chinese Academy of Sciencesthe National Natural Science Foundation of China (Grant No. 29825111)the State Key Laboratory of Electroanalytical Chemistry.
文摘The transfer of sodium and potassium ions facilitated by dibenzo-15-crown-5 (DB15C5) has been studied at the micro-water/l,2-dichloroethane (water/DCE) interface supported at the tip of a micropipette. Cyclic volt-ammetric measurements were performed in two limiting conditions: the bulk concentration of Na+ or K+ in the aqueous phase is much higher than that of DB15C5 in the organic phase (DB15C5 diffusion controlled process) and the reverse condition (metal ion diffusion controlled process). The mechanisms of the facilitated Na+ transfer by DB15C5 are both transfer by interfacial complexation (TIC) with 1:1 stoichiometry under these two conditions, and the corresponding association constants were determined at log β1 = 8.97±0.05 or log β1 = 8.63±0.03. However, the transfers of K+ facilitated by DB15C5 show different behavior. In the former case it is a TIC process and its stoichiometry is 1:2, whereas in the latter case two peaks during the forward scan were observed, the first of which was
