Abstract Capped chelating organic molecules are presented as a design principle for tuning heterogeneous nanoparticles for electrochemical catalysis. Gold nanoparticles (AuNPs) functionalized with a chelating tetradentate porphyrin ligand show a 110‐fold enhancement compared to the oleylamine‐coated AuNP in current density for electrochemical reduction of CO 2 to CO in water at an overpotential of 340 mV with Faradaic efficiencies (FEs) of 93 %. These catalysts also show excellent stability without deactivation (<5 % productivity loss) within 72 hours of electrolysis. DFT calculation results further confirm the chelation effect in stabilizing molecule/NP interface and tailoring catalytic activity. This general approach is thus anticipated to be complementary to current NP catalyst design approaches.
Sulfinates are important lynchpin intermediates in pharmaceutical production; however, their synthesis via photoredox catalysis is challenging because of their facile oxidation. We herein disclose a photocatalytic strategy for the direct conversion of alcohols and alkyl bromides into alkyl sulfinates. These transformations are enabled by the utilization of easily oxidized radical precursors─namely, alcohol N-heterocyclic carbene adducts and N-adamantyl aminosupersilane─that facilitate efficient synthesis of the oxidatively labile sulfinate products. A broad range of functional groups are amenable to the reported transformations, providing rapid access to sulfonamides, sulfonyl halides, sulfones, and sulfonic acids. The utility of these methods is further demonstrated via the late-stage diversification of natural products and drugs into pharmaceutically relevant sulfonamides and "clickable" sulfonyl fluorides. In summary, this work illustrates the potential of novel radical precursors to expand the breadth of photoredox transformations.
Control over the folding of oligomers, be it broad induction of a preferred helical handedness or subtle changes in the orientations of individual functional groups, is important for applications ranging from molecular recognition to long-range conformational communication. Here, we report a series of ortho-phenylene hexamers functionalized with achiral and chiral amides at their termini. NMR spectroscopy, taking advantage of 19F labeling, allows multiple conformers to be detected for each compound. In combination with CD spectroscopy and DFT calculations, specific geometries corresponding to each conformer have been identified and quantified. General conclusions about the effect of sterics and the amide linker on conformational behavior have been drawn, revealing some similarities to and key differences from previously reported imines. A model for twist sense control has been developed that is supported by computational models.
Although alcohols are among the most abundant chemical feedstock, they remain vastly underutilized as coupling partners in transition metal catalysis. Herein, we describe a copper metallaphotoredox manifold for an open shell deoxygenative coupling of alcohols with N-nucleophiles forging C(sp3)–N bonds, a linkage highly sought in pharmaceutical agents but challenging to access via conventional cross-coupling techniques. N-heterocyclic carbene (NHC)-mediated conversion of alcohols into the corresponding alkyl radicals followed by copper-catalyzed C–N coupling renders this platform successful for a broad range of structurally unbiassed alcohols and 18 classes of N-nucleophiles.
Control over the folding of oligomers, be it broad induction of a preferred helical handedness or subtle changes in the orientations of individual functional groups, is important for applications ranging from molecular recognition to long-range conformational communication. Here, we report a series of ortho-phenylene hexamers functionalized with achiral and chiral amides at their termini. NMR spectroscopy, taking advantage of F-19 labeling, allows multiple conformers to be detected for each compound. In combination with CD spectroscopy and DFT calculations, specific geometries corresponding to each conformer have been identified and quantified. General conclusions about the effect of sterics and the amide linker on conformational behavior have been drawn, revealing some similarities and key differences with previously reported imines. A model for twist sense control has been developed that is supported by computational models.
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