Water-soluble, conformationally-immobilized calixarenes (1 and 2 n) with cone and 1,3-alternate conformations have been synthesized: at the para-position of each phenyl unit 1 has a Me3N +CH2 group and 2n has a Me3N +[CH2]nOCH2 group. Examinations with surface tension, fluorescence and dynamic light-scattering established that in water cone-1 aggregates into small micellar particles whereas such molecular aggregates are not detected for 1,3-alternate-1. In In both the cone and 1,3-alternate isomers formed aggregates in water but the cone isomers always gave CAC (critical aggregation concentration) values lower than the 1,3-alternate isomers. These results consistently indicate that the cone 2 n isomers with a cone-shaped hydrophobic surface are more cohesive intermolecularly than the 1,3-alternate 2n isomers with a cylindrical hydrophobic surface. From the molecular shape one can expect that the cone isomers favourably form a globular micelle whereas the 1,3-alternate isomers favourably form a two-dimensional lamella. This was evidenced by the fact that 1,3-alternate-2n can form stable vesicular aggregates detectable by an electron microscope whereas cone-2n cannot form such stable aggregates. These results demonstrate that the aggregation properties of calixarene-containing amphiphiles can be controlled by the conformational structure difference in the calixarene core.
|Number of pages||5|
|Journal||Journal of the Chemical Society, Perkin Transactions 2|
|Publication status||Published - 1995|
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