New catalysts and receptors by self-assembly and combinatorial chemistry

New methods that allow the generation of transition metal-based catalysts and receptors are discussed. It is shown that heterobimetallic, halogeno-bridged complexes are well-suited for screening assays in combinatorial catalysis. Metal catalysts with a structurally defined second coordination sphere can be obtained by molecular imprinting with pseudo-substrate conjugates as exemplified by the substrate-, regio- and stereoselective reduction of ketones, catalyzed by immobilized ruthenium and rhodium complexes. Macrocyclic complexes, formed by self-assembly of organometallic complexes, are shown to act as highly specific receptors for small cations and anions.