Cu2O polyhedra for aryl alkyne homocoupling reactions†
Cu2O cubes, octahedra and rhombic dodecahedra were employed to catalyze homocoupling reactions of aryl alkynes. The X-ray diffraction (XRD) patterns of the Cu2O crystals show slight peak shifts for the different particle shapes, which may be a manifestation of bond-level deviations within the thin surface layer as predicted by density functional theory (DFT) calculations. Infrared spectral characterization indicates acetylenic carbons binding to copper atoms of the Cu2O crystals, and this may be the intermediate state in the coupling reaction. Cu2O rhombic dodecahedra exhibit the best catalytic performance toward homocoupling of phenylacetylene, and they also catalyze homocoupling of a variety of substituted aryl alkynes, showing the advantage of Cu2O facet control to driving important organic coupling reactions.