Mechanisms of sodium and potassium ions transfer facilitated by dibenzo-15-crown-5 across the water/1,2-dichloro-ethane interface using micropipettes  

作　　者：Su, B Shao, YH 

机构地区：[1]Chinese Acad Sci, Changchun Inst Appl Chem, State Key Lab Electroanalyt Chem, Changchun 130022, Peoples R China

出　　处：《Chinese Science Bulletin》2002年第16期1325-1329,共5页

基　　金：This work was supported by the Chinese Academy of Sciences;the National Natural Science Foundation of China (Grant No. 29825111);the State Key Laboratory of Electroanalytical Chemistry.

摘　　要：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 wasThe 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 confirmed as the formation of K+(DB15C5)2 at the interface by a TIC mechanism, while the second one may be another TIC process with 1 : 1 stoichiometry in the more positive potential. The relevant association constants calculated for the complexed ion, K+(DB15C5)2, in the organic phase in two cases, logβ2, are 13.64 ± 0.03 and 11.34± 0.24, respectively.

关 键 词：water/DCE INTERFACE micropipettes FACILITATED ion trans-fer DB15C5. 

分 类 号：O621[理学—有机化学]