Combinatorial libraries and molecular recognition - Match or mismatch?

During the past decade combinatorial libraries have emerged as a major tool for drug discovery and drug development. Especially "one-bead-one-structur e" libraries can be a powerful means for the discovery of ligands to natura l and synthetic hosts and vice versa. Encoded combinatorial libraries have been used to disclose ligands for well-designed macrocyclic host molecules and to elucidate their specificities for peptide sequences. These studies l ed via receptors with more flexibility to simple host molecules without ela borate design that are accessible to combinatorial synthesis. These finding s opened a realm of possibilities and applications. An intriguing one is th e development of chemical sensors for analytes that are otherwise hard or o nly unspecifically detected. Furthermore, such libraries and the techniques that were developed to handle them have been used to find new catalysts an d enzyme mimics.