Glaser coupling- and Sonogashira coupling-control over CuxO nanoparticles/carbon nanotube by switching visible-light off and on

Utilizing CuxO nanoparticles supported on carbon nanotube as catalyst, visible-light could efficiently transform Glaser homo-coupling into Sonogashira cross-coupling. The isolated Sonogashira product yield is up to 0.58 mmol (sel. 97%) under visible-light irradiation while the Glaser product achieves 0.45 mmol (sel. 92%) in the dark for phenylacetylene and iodobenzene. We also discover that the active species under light irradiation is different from that in the dark. The visible light-driven adsorption of aromatic iodides on CuxO nanoparticles and light-excited copper(I) phenylacetylide intermediates together enables the high selectivity of Sonogashira product. The synergistic effect between Cu(II) and Cu(I) acetylide dimer complex enhances the Glaser product yield in the dark.