Synthesis and structure of mono-bridged resorcinarene host: a ditopic receptor for ammonium guests.

The synthesis and structural properties of tetramethoxy resorcinarene mono-crown-5 (1) are described. The binding characteristics of 1 toward acetylcholine and tetramethylammonium salts were investigated by 1H NMR titration. It was observed that the cavity of 1 provides a better fit to acetylcholine compared to the smaller tetramethylammonium cation, as acetylcholine is able to interact with both the crown ether moiety and the free hydroxyl groups of receptor 1 simultaneously.