(547e) Using Bound Organic Ligands to Direct Particle Size and Understand Catalytic Activity of Gold Nanoparticles

The environment around an enzymatic active site is precisely controlled through a combination of geometric confinement as well as precise placement of organic functional groups around the active site. In a nature-inspired approach [1], organic ligands are utilized to surround a metallic active site in order to learn more about how these ligands control access to the active site as well as how they control the activity of the active site.

To investigate the effects that different organic ligand environments have around a catalytic active site, 4-nitrophenol reduction and resazurin reduction were studied using a variety of different phosphine and thiol-containing ligands bound to the gold cluster surface. 4-nitrophenol reduction is widely used to assess the catalytic properties of metallic nanoparticles, and there is debate in the literature as to where the active site is located. [2,3] This comparative study uses these organic ligands with different geometric and electronic properties to gain further insight into the factors that control catalysis in the 4-nitrophenol reduction system.

In the synthesis of metallic clusters, the steric properties of the ligands that are bound to the metal in the precursors affect the final cluster size and accessibility of the final metal clusters. This work uses different phosphine ligands to direct the synthesis of gold clusters/nanoparticles through novel synthetic procedures. [4] These different particles exhibit different amounts of accessibility to the gold cluster surface, depending on the packing of the ligand on the cluster surface. A relationship between the particle size, ligand size, and its accessibility to small probe molecules is demonstrated for these clusters.

References:

1. Trogadas, P.; Nigra, M.M.; Coppens, M.-O.; New J. Chem. 2016, DOI: 10.1039/C5NJ03406J
2. Nigra, M.M.; Ha, J.-M.; Katz, A.; Catal. Sci. Technol. 2013, 3, 2976.
3. Mahmoud, M.A.; Garlyyev, B.; El-Sayed, M.A.; J. Phys. Chem. C 2013, 117, 21886.
4. Nigra, M.M.; Yeh, A.J.; Okrut, A.; DiPasquale, A.G.; Yeh, S.W.; Solovyov, A.; Katz, A.; Dalton Trans. 2013, 42, 12762.