Synthesis and Complexation Properties of "Unsymmetrical" Sucrose-Based Receptors

New unsymmetrical, sucrose-based diaza-crown ethers have been designed and prepared from monosilylated hexa-O-benzylsucrose derivatives. The enantioselective complexation of phenylethylammonium cations by these receptors was evaluated. It was demonstrated that the introduction of the amino group at the 6-position (glucose moiety) in sucrose increases the association constant for the S cation, but reduces the enantioselectivity. On the other hand, introduction of the amino group at the 6-position (fructose moiety) in sucrose increases significantly the value of K-a and at the same time the high enantioselectivity is preserved.