Efficient Complexation of <i>N</i>-Acetyl Amino Acid Carboxylates in Water by an Artificial Receptor:  Unexpected Cooperativity in the Binding of Glutamate but Not Aspartate

Abstract

A new tris-cation 1 binds N-acetyl amino acid carboxylates in water even at millimolar salt concentrations with Kass approximately 103 M-1 due to a clustering of electrostatic interactions. Binding is efficient enough to allow a naked-eyed detection using an indicator displacement assay. Furthermore, receptor 1 shows an unexpected 2:1 complex formation with strong positive cooperativity with glutamate but not aspartate.