(11d) Nanoengineering the Environment Around Catalytic Active Sites

Finely engineered environments around catalytic active sites are a hallmark of enzymatic systems where functional groups are precisely placed, electronic charge is modulated, and hydrophobicity/hydrophilicity is controlled in the active site environment. Translating this precise control around an active site to a heterogeneous catalytic system is a lofty goal in heterogeneous catalysis.

The work presented here will highlight progress made in achieving this goal. One example uses immobilized Rh complexes inside of SBA-15 mesopores where for 1-octene hydroformylation, a rate enhancement was observed for the Rh confined inside of the mesoporous versus the activity of the homogeneous Rh catalyst. [1] . This is an example of using the pores of a support material to influence the environment around an active site. In another example, the environment around catalytically active gold nanoparticles in solution is modulated through different organic ligands bound to the surface of the gold nanoparticles. Using 4-nitrophenol reduction as a test reaction, our work demonstrates that the activity of the catalyst can be altered with different ligands bound to the surface of the gold nanoparticles. The results give additional insight into the active site requirements for 4-nitrophenol reduction when using gold nanoparticles as catalysts. [2, 3]

Further work in the synthesis of small gold clusters with tunable environments will be detailed with 11 atom gold clusters stabilized with organic ligands. The stability, characterization, and catalytic activity of these clusters will be assessed and presented.

1. Marras, F.; Wang, J.; Coppens, M.-O.; Reek, J.N.H.; Chem. Commun. 2010, 46, 6587.

2. Nigra, M.M.; Ha, J.-M.; Katz, A.; Catal. Sci. Technol. 2013, 3, 2976.

3. Nigra, M.M.; Coppens, M.-O. 2017, in preparation.