Effects of doping in 25-atom bimetallic nanocluster catalysts for carbon–carbon coupling reaction of iodoanisole and phenylacetylene

• Main Authors: Zhimin Li, Xiujuan Yang, Chao Liu, Jin Wang, Gao Li
• Format: Article
• Language: English
• Published: Elsevier 2016-10-01
• Series: Progress in Natural Science: Materials International
• Subjects: Au25 nanocluster; Carbon–carbon coupling reactions; Doping effects; Silver; Copper; Platinum
• Online Access: http://www.sciencedirect.com/science/article/pii/S1002007116301058

We here report the catalytic effects of foreign atoms (Cu, Ag, and Pt) doped into well-defined 25-gold-atom nanoclusters. Using the carbon-carbon coupling reaction of p-iodoanisole and phenylacetylene as a model reaction, the gold-based bimetallic MxAu25−x(SR)18 (–SR=–SCH2CH2Ph) nanoclusters (supported on titania) were found to exhibit distinct effects on the conversion of p-iodoanisole as well as the selectivity for the Sonogashira cross-coupling product, 1-methoxy-4-(2-phenylethynyl)benzene). Compared to Au25(SR)18, the centrally doped Pt1Au24(SR)18 causes a drop in catalytic activity but with the selectivity retained, while the AgxAu25−x(SR)18 nanoclusters gave an overall performance comparable to Au25(SR)18. Interestingly, CuxAu25−x(SR)18 nanoclusters prefer the Ullmann homo-coupling pathway and give rise to product 4,4′-dimethoxy-1,1′-biphenyl, which is in opposite to the other three nanocluster catalysts. Our overall conclusion is that the conversion of p-iodoanisole is largely affected by the electronic effect in the bimetallic nanoclusters’ 13-atom core (i.e., Pt1Au12, CuxAu13−x, and Au13, with the exception of Ag doping), and that the selectivity is primarily determined by the type of atoms on the MxAu12−x shell (M=Ag, Cu, and Au) in the nanocluster catalysts.