(611c) Single-Site Supported Catalysts Using Grafted Multidentate Metal-Ligand Complexes
We seek to use multidentate organic ligands to create selective adsorption sites and to control the degree of site isolation, coordination number, and synergistic arrangement of functional groups around supported metal oxide sites. Typically, high surface area supported oxide catalysts can both exhibit complex relationships between function (e.g. turnover rates or adsorption strength), structure (e.g. number of adsorption sites or supported metal oxide domain size and M-O bonding), and synthesis conditions (e.g. loading, precursor identity, or support surface). This complexity is due to the interplay of structure-sensitive catalyst mechanisms with catalytic surfaces that are not easily controlled at the atomic level by traditional synthesis. Here will be demonstrated routes to creating isolated reaction sites of predefined surface densities by surface grafting of multidentate metal-ligand complexes such that synthesis-structure-function interrelationships may be teased out. Subsequent modification of the catalytic surface with organofunctional groups will also be discussed. Select results from new work will be presented that demonstrates our approach to isolated sites via ligand-protected grafting of Mn, Ti, Ta, and Fe. Initial results will be presented on their use in epoxidation and hydroxylation catalysis.