Hydrocarbon transport, inorganic

Simple lipophilic cations, like ammonium ions bearing long hydrocarbon chains, allow anion extraction into an organic phase and render liquid membranes permeable to anions by an anion exchange (antiport) process. Such carriers effect, for instance, selective transport of amino acid carboxylates [6.3] against inorganic anions like chloride. 

Synthetic molecular receptors command widespread interest as mimics of membrane transport agents and enzyme active sites.[1,2] The development of new host systems for the selective complexation of organic and inorganic cations and anions has mushroomed in recent years however, examples of solution phase coordination of neutral organic molecules are few. Most of these examples involve inclusion of an aromatic hydrocarbon into the hydrophobic pocket of a water soluble cyclodextrin or cyclophane receptor.[3-6] A smaller subset of synthetic receptors possess lipophilic exteriors and hydrophilic cavities for the association of polar substrates in nonpolar media. [7-9] We report here the synthesis and characterization of a new system of the latter type designed to bind polar guests in chloroform solution. 

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