Supramolecular metallocatalysts for the cleavage of amino acid esters

Transition metal ions am effective catalysts of the hydrolytic cleavage of amino add esters and their effects can be enhanced and properly directed when they are chelated to functionalized ligands. The resulting metallocatalysts are attracting increasing attention and the systems so far investigated are briefly reviewed. Particular emphasis is given to supramolecular systems which may add to the metallocatalysts the benefits of the cooperativity, set upon convergent non-covalent interactions of their components, needed for substrate recognition. The results obtained with metallomicellar aggregates and molecular metalloreceptors, with particular reference to those studied in the authors' laboratory, are reported in more detail. In the case of loosely structured metallomicelles, remarkable accelerations and, generally, modest selectivities have been observed; less spectacular kinetic effects, but promising substrate selectivity, have been obtained with structurally well defined metalloreceptors.