Product selectivity of alkyne hydroamination over catalytic Au 2 Co alloy nanoparticles (NPs) can be made switchable by al ight-on/light-off process,y ielding imine (cross-coupling product of aniline and alkyne) under visiblelight irradiation, but 1,4-diphenylbutadiyne in the dark. The low-flux light irradiation concentrates aniline on the catalyst, accelerating the catalytic cross-coupling by several orders of magnitude even at av ery low overall aniline concentrations (1.0 10 À3 mol L À1 ). Atentative mechanism is that Au 2 Co NPs absorb light, generating an intense fringing electromagnetic field and hot electrons.T he sharp field-gradient (plasmonic optical force) can selectively enhance adsorption of lightpolarizable aniline molecules on the catalyst. The light irradiation therebya lters the aniline/alkyne ratio at the NPs surface,s witching product selectivity.T his represents an ew paradigm to modify ac atalysis process by light.

Plasmonic catalysis enables the use of light to accelerate molecular transformations. Its application to the control reaction selectivity is highly attractive but remains challenging. Here, we have found that the plasmonic properties in AgPd nanoparticles allowed different reaction pathways for tunable product formation under visible-light irradiation. By employing the hydrogenation of phenylacetylene as a model transformation, we demonstrate that visible-light irradiation can be employed to steer the reaction pathway from hydrogenation to homocoupling. Our data showed that the decrease in the concentration of H species at the surface due to plasmon-enhanced H 2 desorption led to the control in selectivity. These results provide important insights into the understanding of reaction selectivity with light, paving the way for the application of plasmonic catalysis to the synthesis of 1,3-diynes, and bringing the vision of light-driven transformations with target selectivity one step closer to reality.

Production of 2,5-furandicarboxylic acid (FDCA, a platform chemical for the chemical industry in the future) by the selective aerobic oxidation of 5-hydroxymethyl-furfural is a crucial component to enable the FDCA production from sugars. The challenge is to achieve a high FDCA yield at low temperatures. Here, we report a catalyst composed of alloyed nanoparticles (containing 1.5 wt % Ag and 1.5 wt % Pd) supported on CeO2 nanofibers, which achieved an excellent FDCA yield (93%) at 20 °C. Interesting observations include yield deterioration at higher reaction temperatures; water is the source of the oxygen atom(s) added to the oxidized intermediates and product, while O2 molecules adsorbed onto the catalyst scavenge electrons, yielding OH• radicals from OH– ions in the reaction system to drive the oxidation. At 20 °C, we avoid side reactions, but there is no external energy provided for overcoming the activation barriers. The barriers for activating the alcohol groups are significant. We find that the appropriate chemisorption on the catalyst is critical for a high FDCA yield. By tuning the Ag/Pd ratio, we attained the most catalytically active sites, bimetallic surface sites, at the boundaries between Ag and Pd clusters. The chemisorption at these sites is strong enough to cause the selective oxidation of both the aldehyde and alcohol groups in HMF at 20 °C, avoiding side reactions at high temperatures. The knowledge acquired from this study is expected to have implications for other catalytic systems where competitive reactions proceed.

Surface‐plasmon‐mediated phenylacetylide intermediate transfer from the Cu to the Pd surface affords a novel mechanism for transmetalation, enabling wavelength‐tunable cross‐coupling and homo‐coupling reaction pathway control. C−C bond forming Sonogashira coupling and Glaser coupling reactions in O2 atmosphere are efficiently driven by visible light over heterogeneous Cu and Pd nanoparticles as a mixed catalyst without base or other additives. The reaction pathway can be controlled by switching the excitation wavelength. Shorter wavelengths (400–500 nm) give the Glaser homo‐coupling diyne, whereas longer wavelength irradiation (500–940 nm) significantly increases the degree of cross‐coupling Sonogashira coupling products. The ratio of the activated intermediates of alkyne to the iodobenzene is wavelength dependent and this regulates transmetalation. This wavelength‐tunable reaction pathway is a novel way to optimize the product selectivity in important organic syntheses.

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