The development of synthetic host molecules that selectively bind a certain guest molecule from a pool of different guests is a new approach toward molecular recognition. Stereotopic group recognition involves the recognition of one functional group from a (prochiral) guest that contains two of these, chemically equivalent, functional groups. Although this phenomenon has been observed in biochemical processes, the structures of the host-guest complexes involved have never been elucidated due to experimental difficulties. The only example sofar, for which the host-guest complexes have been structurally resolved, involves the binding of a prochiral diammonium ion to a chiral macrocyclic ether host, as studied by the group of Prof. Reetz at the MPI/Kohlen.
The present proposal (enclosed) encompasses the development of new host-guest systems that show stereotopic group recognition and the elucidation of their structures. The latter will be accomplished by NMR and X-ray crystallography for the structure in solution and solid state, respectively. New hosts will be built using macrocyclic amines so that the selectivity for binding of the guests can be influenced by the attachment of different side-chains. The use of chiral metal complexes employing both chiral and achiral ligands, is envisaged, since their properties for binding guests and for structural elucidation may provide new insight and wider application of these systems. The non-coordinated group of the guest will be reacted with other reagents to provide chiral compounds. Training content
The applicant expects that this research may contribute significantly to the areas of molecular recognition and enantioselective catalysis. His presence at the group of Prof. Reetz at the MPI/Kohlen, with its unique knowledge of organic synthesis and molecular recognition, will provide him with a valuable source of experience.