Complex formation between water-soluble calixarenes and dodecylpyridinium chloride

摘要

The complex format ion between water-soluble calixarenes (p-sulfonatocalix[n]arenes, n = 4, 6, 8, CALXSn) and dodecylpyridinium chloride (DPC) has been studied by the potentiometric titration method using a surfactant-selective electrode, at [CALXSn] = 1 X 10~(-4) mol dm~(-3), I=0.01, pH=2.0, 4.0, and 6.9, and 25℃. The observed binding isotherms showed that the binding of DPC to CALXSn occurs in two stages. The first stage is the strong binding to one site, and the second stage is the cooperative binding to the residual sites. White precipitates have been observed at the begining of the second stage. The values of the binding constant and the cooperativity parameter have been found to change with an increase in pH, depending on CALXSn species. These results were discussed from the view point of small cooperative binding system compared to large systems.