In previous work, we have established that electrochemical switching of lariat ether-based ionophores can effect trans- membrane transport of various cations. In the proposed project, we will extend this work by the design and syntheses of highly lipophilic, redox-active crown ethers and podands. Using these compounds, we will develop techniques for cation pumping via chemical and electrochemical gradients. During the course of this work, we have discovered that these highly lipophilic crown ethers, especially those having steroid sidearms, form a novel class of non-ionic liposomes (niosomes). We propose to explore this nearly virgin area and, by use of these novel liposomes, probe the requirements for membrane and vesicle formation. We expect that such compounds will lead to new, unusual structures in which biological-type membranes will have the added dimension of a cation trap on both the inner and outer surfaces. Such assemblies may be of value as membrane models or may be used for specific encapsulation, drug-delivery, etc. In addition, these structures may permit a detailed understanding of the relationship between structural rigidity and cation selectivity. Using structurally related, lipophilic crown ether compounds as novel bolamphiphiles, we will construct novel monolayer vesicles. Use of these novel structures, coupled with our arsenal of NMR, ESR, cyclic voltammetry, ion-selective electrode, and other techniques, will permit us to study the mechanisms of membrane formation, membrane disruption, and cation transport.
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