From Molecular Diversity to Template-Directed Self-Assembly – New Trends in Metallo-Supramolecular Chemistry

Abstract

Molecular diversity can easily be generated in metallo-supramolecular systems by simple mixing of oligodentate ligands and appropriate metal ions. In this reaction either a defined coordination compound is formed in a selective self-assembly process or a mixture is obtained. Depending on the system such a mixture can possess a statistical distribution of components or the formation of some species is thermodynamically favored leading to only a few out of several possible compounds (or in the extreme to only one). Simple well-defined mixtures containing only a few components or pure supramolecular aggregates can be generated from sequential or directional ligands, from mixtures of ligands and/or metals, and by introducing templates which support the formation of defined metallo-supramolecular aggregates. In the latter case it is possible first to generate a mixture of components which are in dynamic equilibrium (dynamic combinatorial library). In a second step, a template can be added, which in a dynamic process transforms such a library into one well-defined species. Thus, the initial generation of molecular diversity allows in a subsequent selection step in an evolutionary process the formation of the most favored receptor/substrate adduct (``dynamic combinatorial chemistry'').