A Highly Enantioselective Receptor for N-Protected Glutamate and Anomalous Solvent-Dependent Binding Properties

Solvation of the macrocycle by polar solvents leads to strong binding of an N-protected excitatory amino acid neurotransmitter. A 1:1 complex forms highly enantioselectively between the macrocycle and N-Boc-L-glutamate (as the dicarboxylate anion, see picture) in CH3CN and DMSO (with a larger entropic driving force for binding), but no binding occurs in the less competitive solvent CDCl3.