3-Substituted-2,4-pentanedionates: Ligands for photoactive supramolecular assemblies

Synthetic routes for the construction of 3-substituted 2,4-pentadionate ligands are broadly surveyed. They involve sequential alkylation and arylation by numerous methods, including those based on reactions of coordinated ligands, and can provide access to various rationally designed ligands. Applications of such ligands in the synthesis of multichromophoric complexes are illustrated in some detail. Incorporation of 3-substituted 2,4-pentanedione units into mesomorphic and macromolecular structures is considered in relation to structural control of energy and electron transfer processes in photoactive systems. Aspects of the general supramolecular chemistry of complexes of 3-substituted-2,4-pentadionate ligands are briefly discussed to illustrate the utility of such species within the full range of 1,3-dionate chemistry.