摘要：

The catalytic activity of well-defined gold nanorods enclosed by Au(111) and Au(100) surfaces is investigated for the Sonogashira cross-coupling reaction between phenylacetylene and 4-iodoanisole, which gives rise to two homo-coupling products (diphenyldiacetylene, PhC C C CPh and 4,4′-dimethoxy-1,1′-biphenyl, MeOC 6 H 4 C 6 H 4 OMe) and a cross-coupling product (1-methoxy-4-(2-phenylethynyl)benzene, PhC CC 6 H 4 OMe). This study shows that shorter nanorods (33nm) with a higher percentage of Au(111) surface are considerably more selective toward the cross-coupling product (57% conversion with 90% selectivity). The selectivity of longer nanorods (e.g., 42 and 50nm) with a higher percentage of Au(100) surface, as well as of corresponding shapeless gold nanoparticles (e.g., 2–4 and 20nm), is found to be less than 59%. The catalytic mechanism of the homo- and cross-coupling reactions, in particular, roles played by Au(100) and Au(111) surfaces, is examined via DFT simulation. It is found that iodobenzene adsorption, C I bond dissociation, reactant surface diffusion, and coupling reactions are more favorable on Au(111) than on Au(100). This work demonstrates the gold facet effect on catalytic coupling reactions, and the combined approach of experiment and theory permits mechanistic understanding at the molecular level.

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