Sonogashira Couplings on the Surface of Montmorillonite-Supported Pd/Cu Nanoalloys

• Published in: ACS applied materials & interfaces 2014-11, Vol.6 (22), p.20261-20268
• Main Authors: Xu, Wei, Sun, Huaming, Yu, Bo, Zhang, Guofang, Zhang, Weiqiang, Gao, Ziwei
• Format: Article
• Language: English
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/am505798y

To explore the true identity of palladium-catalyzed Sonogashira coupling reaction, montmorillonite (MMT)-supported transition metal nanoparticles (MMT@M, M = Pd, Cu, Fe, and Ni) were prepared, characterized, and evaluated systematically. Among all MMT@M catalysts, MMT@Pd/Cu showed the highest activity, and it was successfully extended to 20 examples with 57%–97% yields. The morphology characterization of MMT@Pd/Cu revealed that the crystalline bimetallic particles were dispersed on a MMT layer as nanoalloy with diameters ranged from 10 to 11 nm. In situ IR analysis using CO as molecular probe and XPS characterization found that the surface of Pd/Cu particles consisted of both catalytic active sites of Pd(0) and Cu­(I). The experiments on the catalytic activities of MMT@M found that Pd/Cu catalyst system exhibited high activity only in nanoalloy form. Therefore, the Pd/Cu nanoalloy was identified as catalyst, on which the interatom Pd/Cu transmetalation between surfaces was proposed to be responsible for its synergistic activity.