New guanidinium-based carboxylate receptors derived from 5-amino-pyrrole-2-carboxylate: synthesis and first binding studies

The synthesis and binding properties of a new class of amino pyrrole based receptors 2 for carboxylates are described. The reversal of the direction of the amide group changes both substrate selectivity and binding affinity relative to known guanidiniocarbonyl pyrrole receptors of type 1 derived from pyrrole-2,5-dicarboxylates.