Although carbon dioxide (CO2) is highly abundant, its low reactivity has limited its use in chemical synthesis. In particular, methods for carbon–carbon bond formation generally rely on two-electron mechanisms for CO2 activation and require highly activated reaction partners. Alternatively, radical pathways accessed via photoredox catalysis could provide new reactivity under milder conditions. Here we demonstrate the direct coupling of CO2 and amines via the single-electron reduction of CO2 for the photoredox-catalyzed, continuous flow synthesis of α-amino acids. By leveraging advantages for utilizing gases and photochemistry in flow, a commercially available organic photoredox catalyst effects the selective α-carboxylation of amines bearing various functional groups and heterocycles. Preliminary mechanistic studies support CO2 activation and carbon–carbon bond formation via single-electron pathways, and we expect that this strategy will inspire new perspectives on using this feedstock chemical in organic synthesis.

The direct β-selective hydrocarboxylation of styrenes under atmospheric pressure of CO has been developed using photoredox catalysis in continuous flow. The scope of this methodology was demonstrated with a range of functionalized terminal styrenes, as well as α-substituted and β-substituted styrenes.

An electrochemically driven, nickel-catalyzed reductive coupling of N-hydroxyphthalimide esters with aryl halides is reported. The reaction proceeds under mild conditions in a divided electrochemical cell and employs a tertiary amine as the reductant. This decarboxylative C(sp3)–C(sp2) bond-forming transformation exhibits excellent substrate generality and functional group compatibility. An operationally simple continuous-flow version of this transformation using a commercial electrochemical flow reactor represents a robust and scalable synthesis of value added coupling process.

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Anthropogenic carbon dioxide (CO2) emission from the combustion of fossil fuels is a major contributor to global climate change and ocean acidification. The implementation of carbon capture and storage technologies has been proposed to mitigate the buildup of this greenhouse gas in the atmosphere. Among these technologies, direct air capture is regarded as a plausible CO2 removal tool whereby net negative emissions can be achieved. However, the separation of CO2 from air is particularly challenging due to the ultradilute concentration of CO2 in the presence of high concentrations of dioxygen and water. Here, we report a robust electrochemical redox-active amine system demonstrating a high electron utilization (i.e., mole of CO2 per mole of electrons) of up to 1.25 with the capture of two CO2 molecules per amine in an aqueous solution with a work of 101 kJe per moles of CO2. The capture of CO2 directly from ambient air as the feed gas presented an electron utilization of 0.78.

Transfer and inversion of supramolecular chirality from chiral calix[4]arene analogs (3D and 3L) with an alanine moiety to an achiral bipyridine derivative (1) with glycine moieties in a coassembled hydrogel are demonstrated. Molecular chirality of 3D and 3L could transfer supramolecular chirality to an achiral bipyridine derivative 1. Moreover, addition of 0.6 equiv of 3D or 3L to 1 induced supramolecular chirality inversion of 1. More interestingly, the 2D-sheet structure of the coassembled hydrogels formed with 0.2 equiv of 3D or 3L changed to a rolled-up tubular structure in the presence of 0.6 equiv of 3D or 3L. The chirality inversion and morphology change are mainly mediated by intermolecular hydrogen-bonding interactions between the achiral and chiral molecules, which might be induced by reorientations of the assembled molecules, confirmed by density functional theory calculations.

Direct air capture of carbon dioxide is a viable option for the mitigation of CO2 emissions and their impact on global climate change. Conventional processes for carbon capture from ambient air require 230 to 800 kJ thermal per mole of CO2, which accounts for most of the total cost of capture. Here, we demonstrate electrochemical direct air capture using neutral red as a redox-active material in an aqueous solution enabled by the inclusion of nicotinamide as a hydrotropic solubilizing agent. The electrochemical system demonstrates a high electron utilization of 0.71 in a continuous flow cell with an estimated minimum work of 35 kJe per mole of CO2 from 15% CO2. Further exploration using ambient air (410 ppm CO2 in the presence of 20% oxygen) as a feed gas shows electron utilization of 0.38 in a continuous flow cell to provide an estimated minimum work of 65 kJe per mole of CO2.

Carbond ioxide (CO 2 )i san attractive building block for organic synthesis that is environmentally friendly.C ontinuous flow technologies have enabled C À Oa nd C À Cb ondf orming reactions with CO 2 that previously were either low-yielding or impossible in batch to affordv alue-added chemicals. This review describes recent advancesi nc ontinuous flow as an enabling strategyi nu tilizing CO 2 as aC 1 building block in chemical synthesis.