Low-dimensional heterostructures for advanced electrocatalysis: an experimental and computational perspective

The development of LD heterostructure nanomaterials represents a powerful strategy totailor the electrocatalytic function of several interfacial active sites at the subnanometer level.

Carbene and Photocatalyst-Catalyzed Decarboxylative Radical Coupling of Carboxylic Acids and Acyl Imidazoles to Form Ketones

The carbene and photocatalyst co-catalyzed radical coupling of acyl electrophile and a radical precursor is emerging as attractive method for ketone synthesis. However, previous reports mainly limited to prefunctionalized radical precursors and two-component coupling. Herein, an N-heterocyclic carbene and photocatalyst catalyzed decarboxylative radical coupling of carboxylic acids and acyl imidazoles is disclosed, in which the carboxylic acids were directly used as radical precursors. The acyl imidazoles could also be generated in situ by reaction of a carboxylic acid with CDI thus furnishing a formally decarboxylative coupling of two carboxylic acids. In addition, the reaction was successfully extended to three-component coupling by using alkene as a third coupling partner via a radical relay process. The mild conditions, operational simplicity, and use of carboxylic acids as the reacting partners make our method a powerful strategy for construction of complex ketones from readily available starting materials, and late-stage modification of natural products and medicines.

Medium-Length Lipids Facilitate Cell-Permeability and Bioactivity

The majority of bioactive molecules act on membrane proteins or intracellular targets and therefore needs to partition into or cross biological membranes. Natural products often exhibit lipid modifications to facilitate critical molecule-membrane interactions and in many cases their bioactivity is markedly reduced upon removal of a lipid group. However, despite its importance in nature, lipid-conjugation of small molecules is not commonly used in chemical biology and medicinal chemistry, and the effect of such conjugation has not been systematically studied. To understand the composition of lipids found in natural products, we carried out a chemoinformatic characterization of the ‘natural product lipidome’. According to this analysis, lipidated natural products predominantly contain saturated linear medium-length lipids, which are significantly shorter than those found in membranes and lipidated proteins. To study the usefulness of such modifications in probe design, we systematically explored the effect of lipid conjugation on five different small molecule chemotypes and find that permeability, cellular retention, subcellular localization, and bioactivity can be significantly modulated depending on the type of lipid tail used. We demonstrate that medium-length lipid tails can render impermeable molecules cell-permeable and switch on their bioactivity. Saturated medium-length lipids (e.g. C10) are found to be ideal for the bioactivity of small molecules in mammalian cells, while saturated long-chain lipids (e.g. C18) often significantly reduce bioavailability and activity. Together, our findings suggest that conjugation of small molecules with medium-length lipids could be a powerful strategy for the design of probes and drugs.

Catalytic, contra-Thermodynamic Alkene Isomerization

The positional isomerization of C–C double bonds is a powerful strategy for the interconversion of alkene regioisomers. However, existing methods provide access to thermodynamically more stable isomers from less stable starting materials. Here we report the discovery of a dual catalyst system that promotes contra-thermodynamic positional alkene isomerization under photochemical irradiation, providing access to terminal alkene isomers directly from conjugated, internal alkene starting materials. The utility of the method is demonstrated in the deconjugation of diverse electron rich/poor alkenes and through strategic application to natural product synthesis. Mechanistic studies are consistent with a regiospecific bimolecular homolytic substitution (SH2') mechanism proceeding through an allyl-cobaloxime intermediate.

Linking metal-organic cages pairwise as a design approach for assembling multivariate crystalline materials

Using metal-organic cages (MOCs) as preformed supermolecular building-blocks (SBBs) is a powerful strategy to design functional metal-organic frameworks (MOFs) with control over the pore architecture and connectivity. However, introducing chemical complexity into the network via this route is limited as most methodologies focus on only one type of MOC as the building-block. Herein we present the pairwise linking of MOCs as a design approach to introduce defined chemical complexity into porous materials. Our methodology exploits preferential Rh-aniline coordination and stoichiometric control to rationally link Cu4L4 and Rh4L4 MOCs into chemically complex, yet extremely well-defined crystalline solids. This strategy is expected to open up significant new possibilities to design bespoke multi-functional materials with atomistic control over the location and ordering of chemical functionalities.

Insecticide resistance by a host-symbiont reciprocal detoxification

Insecticide resistance is one of the most serious problems in contemporary agriculture and public health. Although recent studies revealed that insect gut symbionts contribute to resistance, the symbiont-mediated detoxification process remains unclear. Here we report the in vivo detoxification process of an organophosphorus insecticide, fenitrothion, in the bean bug Riptortus pedestris. Using transcriptomics and reverse genetics, we reveal that gut symbiotic bacteria degrade this insecticide through a horizontally acquired insecticide-degrading enzyme into the non-insecticidal but bactericidal compound 3-methyl-4-nitrophenol, which is subsequently excreted by the host insect. This integrated “host-symbiont reciprocal detoxification relay” enables the simultaneous maintenance of symbiosis and efficient insecticide degradation. We also find that the symbiont-mediated detoxification process is analogous to the insect genome-encoded fenitrothion detoxification system present in other insects. Our findings highlight the capacity of symbiosis, combined with horizontal gene transfer in the environment, as a powerful strategy for an insect to instantly eliminate a toxic chemical compound, which could play a critical role in the human-pest arms race.

Developing Teams in a Virtual Environment: A Generative Approach

At the beginning of 2020, the operations of the Finance Hub of the Americas (FHoA) at pharmaceutical company GlaxoSmithKline (GSK) were suddenly forced to shift entirely from face-to-face to remote work. To handle this challenge, an FHoA team started a team development process aimed at strengthening teamwork in virtual environments. The intervention was grounded in the principles of generative leadership and dialogic organization development. Through a scholar-practitioner collaboration that focused on identifying the drivers of the successful transition to remote work, we build a three-step process of team development using the metaphor of organic growth: (1) sowing, (2) nurturing, and (3) flourishing. Using GSK's example, we illustrate how this process became a simple but powerful strategy to help teams thrive in a virtual environment. The core of the process uses generative questions to configure a structured but adaptable process that can be easily implemented in different contexts and situations.

Recent Advances on Transition Metal-Catalyzed Direct Asymmetric C‒H Arylation Reactions

Transition metal-catalyzed direct asymmetric C−H functionalization has become a powerful strategy to synthesize complex chiral molecules. Recently, catalytic enantioselective C−H arylation has attracted great interest from organic chemists to construct aryl-substituted chiral compounds. In this short review, we intend to highlight the recent advancements in asymmetric C−H arylation from 2019 to now, including enantioselective C(sp2)−H arylation to construct axial or planar chiral compounds, and enantioselective C(sp3)−H arylation to introduce central chirality via desymmetrization of methyl group or direct methylene C–H activation. These processes proceed with palladium, rhodium, iridium, nickel or copper catalyst, and utilize aryl halides, boron or diazo derivatives as arylation reagents.

PermaPhosSer: autonomous synthesis of functional, permanently phosphorylated proteins

Installing stable, functional mimics of phosphorylated amino acids into proteins offers a powerful strategy to study protein regulation. Previously, a genetic code expansion (GCE) system was developed to translationally install non-hydrolyzable phosphoserine (nhpSer), with the γ-oxygen replaced with carbon, but it has seen limited usage. Here, we achieve a 40-fold improvement in this system by engineering into Escherichia coli a biosynthetic pathway that produces nhpSer from the central metabolite phosphoenolpyruvate. Using this "PermaPhosSer" system — an autonomous 21-amino acid E. coli expression system for incorporating nhpSer into target proteins — we show that nhpSer faithfully mimics the effects of phosphoserine in three stringent test cases: promoting 14-3-3/client complexation, disrupting 14-3-3 dimers, and activating GSK3-β phosphorylation of the SARS-CoV-2 nucleocapsid protein. This facile access to nhpSer containing proteins should allow nhpSer to replace Asp and Glu as the go-to pSer phosphomimetic for proteins produced in E. coli.