Studying single catalyst nanoparticles, during reaction, eliminates averaging effects that are an inherent limitation of ensemble experiments. It enables establishing structure–function correlations beyond averaged properties by including particle-specific descriptors such as defects, chemical heterogeneity and microstructure. Driven by these prospects, several single particle catalysis concepts have been implemented. However, they all have limitations such as low throughput, or that they require very low reactant concentrations and/or reaction rates. In response, we present a nanofluidic device for highly parallelized single nanoparticle catalysis in solution, based on fluorescence microscopy. Our device enables parallel scrutiny of tens of single nanoparticles, each isolated inside its own nanofluidic channel, and at tunable reaction conditions, ranging from the fully mass transport limited regime to the surface reaction limited regime. In a wider perspective, our concept provides a versatile platform for highly parallelized single particle catalysis in solution and constitutes a promising application area for nanofluidics.
A catalyst-free, stereoselective
visible-light-driven annulation
reaction between alkenes and
N
,
N
-substituted dialkyl anilines for the synthesis of substituted tetrahydroquinolines
is presented. The reaction is driven by the photoexcitation of an
electron donor–acceptor (EDA) complex, and the resulting products
are obtained in good to high yields with complete diastereoselectivity.
Mechanistic rationale and photochemical characterization of the EDA-complex
are provided.
A catalytic electron
donor–acceptor (EDA) complex for the
visible-light-driven annulation reaction between activated alkenes
and N,N-substituted dialkyl anilines is reported. The key photoactive
complex is formed
in situ
between dialkylated anilines
as donors and 1,2-dibenzoylethylene as a catalytic acceptor. The catalytic
acceptor is regenerated by aerobic oxidation. Investigations into
the mechanism are provided, revealing a rare example of a catalytic
acceptor in photoactive EDA complexes that can give access to selective
functionalization of aromatic amines under mild photochemical conditions.
An additive-free,
visible light-driven annulation between N-aryl amino
acids and maleimide to form tetrahydroquinolines
(THQs) is disclosed. Photochemical activation of an electron donor–acceptor
(EDA) complex between amino acids and maleimides drives the reaction,
and aerobic oxygen acts as the terminal oxidant in the net oxidative
process. A range of N-aryl amino acids and maleimides
have been investigated as substrates to furnish the target THQ in
good to excellent yield. Mechanistic investigations, including titration
and UV–vis studies, demonstrate the key role of the EDA complex
as the photoactive species.
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