Plasmonic Switching of the Reaction Pathway: Visible‐Light Irradiation Varies the Reactant Concentration at the Solid–Solution Interface of a Gold–Cobalt Catalyst

Abstract

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.

Dual-Function, Light Switchable Cobalt Catalysis via Active Site Metamorphosis

“…13 C NMR (151 MHz, Chloroform-d) δ 82.8, 40.4, 37.4, 33.4, 26.7, 26.4, 24.8, 21.3. IR (neat): ν = 2978, 2921, 2850, 2324, 2107, 1807, 1449, 1371, 1316, 1145, 968, 844 cm -1 HRMS (ESI): m/z [M+H] + for C15H29BO2 calcd: 253.2339; found: 253.2336.Spectroscopic data match with those reported previously in the literature 11. Prepared following general procedure D, 4c was obtained after purification by column chromatography (pentane/Et2O 9:1), as a colorless liquid (37 mg, 70%).…”

“…8 Considerably rarer is switching selectivity between two entirely different reactions. 9 Indeed, within the area of transition metal catalysis, only a few examples with light have been reported [10][11][12][13] and the majority only demonstrate different outcomes in the light and the dark rather than truly falling into the category of switchable, reversible reactions. 14 One simple method for modifying the active site of a transition metal complex is to use light to dissociate a ligand ( Figure 1).…”

Kinetically Stable Nonequilibrium Gold‐Cobalt Alloy Nanoparticles with Magnetic and Plasmonic Properties Obtained by Laser Ablation in Liquid

“…Interestingly, the blue shift and the quenching of the SPR were not observed in a recent report about Au−Co alloys supported on oxide substrates by coprecipitation method, where a peak at 520 nm is noted. This was presumably due to the lower efficacy of the wet chemistry approach for the synthesis of nonequilibrium nanoalloys [20] . Therefore, the UV‐vis spectroscopy further corroborated the alloy character of the Au−Co NPs obtained by LASiS.…”

“…Some of these methods are of difficult management or scale‐up, such as gamma‐rays irradiation, or give agglomerated products, such as ball‐milling or laser spray pyrolysis [7,19] . Other methods may give agglomerated products with a purity that is affected by chemical residuals or contaminants, such as the co‐precipitation of metal precursors with strong reducing agents in the liquid phase [7,8,20] . Other approaches, such as physical or chemical vapour deposition and solid‐state dewetting, are not compatible with large scale production of colloidal particles, [21] that represent the optimal dispersion state for NPs bioconjugation or inclusion in the desired matrixes and devices, such as polymeric films and multilayers [22] …”

Visible‐Light Controlled Divergent Catalysis Using a Bench‐Stable Cobalt(I) Hydride Complex

“…Indeed, within the area of transition‐metal catalysis, only a handful of examples have been reported. Just recently, Zhu, Sarina and co‐workers reported a specific example in which gold–cobalt nanoparticles enabled the formation of imines from anilines and arylalkynes under visible‐light irradiation . In contrast, without light, they observed only homocoupling of the alkyne.…”