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Enzymatic cleavage of C─F bonds in per- and polyfluoroalkyl substances (PFAS) is largely unknown but avidly sought to promote systems biology for PFAS bioremediation. Here, we report the reductive defluorination of α, β-unsaturated per- and polyfluorocarboxylic acids by Acetobacterium spp. The microbial defluorination products were structurally confirmed and showed regiospecificity and stereospecificity, consistent with their formation by enzymatic reactions. A comparison of defluorination activities among several Acetobacterium species indicated that a functional fluoride exporter was required for the detoxification of the released fluoride. Results from both in vivo inhibition tests and in silico enzyme modeling suggested the involvement of enzymes of the flavin-based electron-bifurcating caffeate reduction pathway [caffeoyl-CoA reductase (CarABCDE)] in the reductive defluorination. This is a report on specific microorganisms carrying out enzymatic reductive defluorination of PFAS, which could be linked to electron-bifurcating reductases that are environmentally widespread.

The photochemical dynamics of the acetic acid and trifluoro-acetic acid dimers in hexane are studied using time-resolved infrared absorption spectroscopy and ab initio electronic structure calculations. The different hydrogen bond strengths of the two systems lead to changes in the character of the accessed excited states and in the timescales of the initial structural rearrangement that define the early time dynamics following UV excitation. The much stronger hydrogen bonding in the acetic acid dimer stabilizes the system against dissociation. Ground state recovery is mediated by a structural buckling around the hydrogen bond itself with no evidence for excited state proton transfer processes that are usually considered to drive ultrafast relaxation processes in hydrogen bonded systems. The buckling of the ring leads to relaxation through two conical intersections and the eventual reformation of the electronic and vibrational ground states on a few picosecond timescale. In trifluoro-acetic acid, the weaker hydrogen bonding interaction means that the dimer dissociates under similar irradiation conditions. The surrounding solvent cage restricts the full separation of the monomer components, meaning that the dimer is reformed and returns to the ground state structure via a similar buckled structure but over a much longer, ∼100 ps, timescale. [ABSTRACT FROM AUTHOR]

Ammonium and carboxylic moieties play a central role in proton-mediated processes of molecular recognition, charge transfer or chemical change in (bio)materials. Whereas both chemical groups constitute acid–base pairs in organic salt-bridge structures, they may as well host excess protons in acidic environments. The binding of excess protons often precedes proton transfer reactions and it is therefore of fundamental interest, though challenging from a quantum chemical perspective. As a benchmark for this process, we investigate proton storage in the amphoteric compound 5-aminovaleric acid (AV), within an intramolecular proton bond shared by its primary amine and carboxylic acid terminal groups. Infrared ion spectroscopy is combined with ab initio Molecular Dynamics (AIMD) calculations to expose and rationalize the spectral signatures of protonated AV and its deuterated isotopologues. The dynamic character of the proton bond confers a fluxional structure to the molecular framework, leading to wide-ranging bands in the vibrational spectrum. These features are reproduced with remarkable accuracy by AIMD computations, which serves to lay out microscopic insights into the excess proton binding scenario. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO) is a two-dimensional, mechanically strong, and chemically tunable material for separations. Elucidating GO–ion–water interactions at the molecular scale is highly important for predictive understanding of separation systems. However, direct observations of the nanometer region by GO surfaces under operando conditions are not trivial. Therefore, thin films of GO at the air/water interface can be used as model systems. With this approach, we study the effects of alkali metal ions on water organization near graphene oxide films at the air/water interface using vibrational sum frequency generation (SFG) spectroscopy. We also use an arachidic acid Langmuir monolayer as a benchmark for a pure carboxylic acid surface. Theoretical modeling of the concentration-dependent sum frequency signal from graphene oxide and arachidic acid surfaces reveals that the adsorption of monovalent ions is mainly controlled by the carboxylic acid groups on graphene oxide. An in-depth analysis of sum frequency spectra reveals at least three distinct water populations with different hydrogen bonding strengths. The origin of each population can be identified from concentration dependent variations of their SFG signal. Interestingly, an interfacial water structure seemed mostly insensitive to the character of the alkali cation, in contrast to similar studies conducted at the silica/water interface. However, we observed an ion-specific effect with lithium, whose strong hydration prevented direct interactions with the graphene oxide film. [ABSTRACT FROM AUTHOR]

DNA-encoded library technology grants access to nearly infinite opportunities to explore the chemical structure space for drug discovery. Successful navigation depends on the design and synthesis of libraries with appropriate physicochemical properties (PCPs) and structural diversity while aligning with practical considerations. To this end, we analyze combinatorial library design constraints including the number of chemistry cycles, bond construction strategies, and building block (BB) class selection in pursuit of ideal library designs. We compare two-cycle library designs (amino acid + carboxylic acid, primary amine + carboxylic acid) in the context of PCPs and chemical space coverage, given different BB selection strategies and constraints. We find that broad availability of amines and acids is essential for enabling the widest exploration of chemical space. Surprisingly, cost is not a driving factor, and virtually, the same chemical space can be explored with budget BBs.

The total oxidizable precursor (TOP) assay has been extensively used for detecting PFAS pollutants that do not have analytical standards. It uses hydroxyl radicals (HO•) from the heat activation of persulfate under alkaline pH to convert H-containing precursors to perfluoroalkyl carboxylates (PFCAs) for target analysis. However, the current TOP assay oxidation method does not apply to emerging PFAS because (i) many structures do not contain C-H bonds for HO• attack and (ii) the transformation products are not necessarily PFCAs. In this study, we explored the use of classic acidic persulfate digestion, which generates sulfate radicals (SO4-•), to extend the capability of the TOP assay. We examined the oxidation of Nafion-related ether sulfonates that contain C-H or -COO-, characterized the oxidation products, and quantified the F atom balance. The SO4-• oxidation greatly expanded the scope of oxidizable precursors. The transformation was initiated by decarboxylation, followed by various spontaneous steps, such as HF elimination and ester hydrolysis. We further compared the oxidation of legacy fluorotelomers using SO4-• versus HO•. The results suggest novel product distribution patterns, depending on the functional group and oxidant dose. The general trends and strategies were also validated by analyzing a mixture of 100000- or 10000-fold diluted aqueous film-forming foam (containing various fluorotelomer surfactants and organics) and a spiked Nafion precursor. Therefore, (1) the combined use of SO4-• and HO• oxidation, (2) the expanded list of standard chemicals, and (3) further elucidation of SO4-• oxidation mechanisms will provide more critical information to probe emerging PFAS pollutants.

Visible light mediated decarboxylative functionalization of carboxylic acids and their derivatives has recently emerged as a novel and powerful toolkit for small molecule activation in diverse carbon–carbon and carbon–hetero bond forming reactions. Naturally abundant highly functionalized bench-stable carboxylic acid analogs have been employed as promising alternatives to non-trivial organometallic reagents for mild and eco-benign synthetic transformation with traceless CO2 by-products. In this highlight article, we focus on the development of various photodecarboxylative functionalization strategies along with intra/inter-molecular cyclization via concerted single electron transfer (SET) or energy transfer (ET) pathways. Moreover, widely explored carboxylic acids are systematically classified here into four categories; i.e., α-keto, aliphatic, α,β-unsaturated, and aromatic analogs for a concise overview to the readership. The association of decarboxylative radical species with coupling partners to construct C–C and C–N/O/S/P/X bonds for each analogous acid has been presented in brief. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: CO2 is an abundant, nontoxic, and renewable C1 feedstock in synthetic chemistry. Direct carboxylation of readily available olefins incorporating CO2 is regarded as a promising strategy to access high value‐added carboxylic acids as well as CO2 fixation. However, due to the thermodynamic stability and kinetic inertness of CO2 and the difficulty in controlling the regioselectivity, the carboxylation of olefins with CO2 still remains challenging. Radical‐type functionalization with olefins represented a powerful protocol and enabled the development of novel transformations in this realm. More recently, the advance of new technology, such as photoredox catalysis and the renaissance of electrochemistry in organic synthesis, offered access to unique chemical reactivities of radical precursors and provided new solutions to the functionalization of olefins. This review presents the recent advances in the radical‐type carboxylation of olefins, which has mainly been achieved through photocatalysis and electrocatalysis in the last decade. In this article, we provide a comprehensive introduction of the progress, summarize the advantages and limitations of current research, and discuss the potential outlook for further development. Key Scientists: [ABSTRACT FROM AUTHOR]

Schematic illustration of the mechanism by which universal NR promotes Fenton/Fenton-like reactions. [Display omitted] Fenton/Fenton-like reaction induced chemical dynamic therapy (CDT) has been widely recognized in tumor therapy. Due to the low efficiency of conversion from high-valent metal ions (M(n+1)+) to low-valent ions (M n+) in the Fenton/Fenton-like catalytic process, enhancing the conversion efficiency safely and effectively would create a great opportunity for the clinical application of CDT. In the study, a universal nanoreactor (NR) consisting of liposome (Lip), tumor cell membrane (CM), and bis(2,4,5-trichloro-6-carboxyphenyl) oxalate (CPPO) is developed to tackle this challenge. The CPPO was first discovered to decompose under weak acidity and H 2 O 2 conditions to generate carboxylic acids (R′COOH) and alcohols (R′OH) with reducibility, which will reduce M(n+1)+ to M n+ and magnify the effect of CDT. Furthermore, glucose oxidase (GOx) was introduced to decompose glucose in tumor and generate H 2 O 2 and glucose acid, which promote the degradation of CPPO, further strengthening the efficiency of CDT, leading to a butterfly effect. This demonstrated that the butterfly effect triggered by NR and GOx encourages Fenton/Fenton-like reactions of Fe 3 O 4 and MoS 2 , thereby enhancing the tumor inhibition effect. The strategy of combining GOx and CPPO to strengthen the Fenton/Fenton-like reaction is a universal strategy, which provides a new and interesting perspective for CPPO in the application of CDT, reflecting the exquisite integration of Fenton chemistry and catalytic medicine. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: CO2 is an abundant, nontoxic, and renewable C1 feedstock in synthetic chemistry. Direct carboxylation of readily available olefins incorporating CO2 is regarded as a promising strategy to access high value‐added carboxylic acids as well as CO2 fixation. However, due to the thermodynamic stability and kinetic inertness of CO2 and the difficulty in controlling the regioselectivity, the carboxylation of olefins with CO2 still remains challenging. Radical‐type functionalization with olefins represented a powerful protocol and enabled the development of novel transformations in this realm. More recently, the advance of new technology, such as photoredox catalysis and the renaissance of electrochemistry in organic synthesis, offered access to unique chemical reactivities of radical precursors and provided new solutions to the functionalization of olefins. This review presents the recent advances in the radical‐type carboxylation of olefins, which has mainly been achieved through photocatalysis and electrocatalysis in the last decade. In this article, we provide a comprehensive introduction of the progress, summarize the advantages and limitations of current research, and discuss the potential outlook for further development. Key Scientists: [ABSTRACT FROM AUTHOR]

We have selected a semi-rigid hexacarboxylic acid ligand H6L enriched with oxygen-active sites with Cd2+ salt, successfully synthesising a 3-D anionic material MOF-1 ([(CH3)2NH2]2[Cd2L]·3DMA·2H2O, H6L = 5,5',5"-(benzene-1,3,5-triyltris(oxy))triisophthalic acid). The structure of this carboxylic acid ligand is triangular in shape, which contributes to the formation of the 3-D framework structure, and its semi-rigidity facilitates entry of dye molecules by slightly adjusting the pore size. The larger pore size of MOF-1 is 1.45 nm x 0.86 nm. The oxygen spacer groups are uniformly distributed throughout the framework, promoting the adsorption of MOF-1 for dyes. Based on these factors, there is a significant advantage in that the anionic material MOF-1 containing [(CH3)2NH2]+ selectively adsorbs cationic organic dyes from aqueous contaminants for recycling. It was discovered that the adsorption process' equilibrium and kinetics followed the Langmuir isothermal model and pseudo-secondary kinetics, respectively. And we measured the adsorption rate of MOF-1' on MB+ to be 1.77 x 10-3 g mg-1 min-1. Its relatively high capacity is ca. 1220 mg g-1. After five cycles of adsorption and desorption, the dye adsorption performance was reduced to ca. 80% and the framework stability remained well. [ABSTRACT FROM AUTHOR]

Octacalcium phosphate (OCP), an inorganic compound with a layered structure that can incorporate various carboxylic acids, exhibits fluorescence when aromatic carboxylate ions are present in the inter- layers. However, the incorporation of carboxylate ions into OCP involves molecular selectivity, and the synthesis of novel OCP materials with incorporated terephthalate ion derivatives is particularly challen- ging. In this study, we incorporated 4-(carboxymethyl)benzoate and 1,4-phenylenediacetate ions into OCP for the first time and investigated the resulting fluorescence properties. The relationship between the (100) interplanar spacing and size of the incorporated dicarboxylate ions revealed that 4-(carboxy- methyl)benzoate ions have a relaxed structure in the OCP interlayers, whereas the structure of the 1,4- phenylenediacetate ions is elongated by approximately 10% relative to that of the stable conformation. OCP with incorporated 1,4-phenylenediacetate ions showed blue fluorescence at 286 nm under 254 nm excitation. In contrast, distinct from previously reported fluorescent OCPs, OCP with incorporated 4-(carboxymethyl)benzoate ions exhibited two-colour fluorescence, with pink emission under 254 nm excitation and blue emission under 312 and 365 nm excitation. This OCP material exhibiting fluorescence at two wavelengths in the visible-light range offers new possibilities for practical applications. In particular, these unique fluorescence characteristics combined with the excellent biological properties of OCP can be exploited to develop novel biofriendly fluorescent probes. These findings contribute to an improved understanding of fundamental calcium phosphate chemistry and should encourage further research on functional OCP materials. [ABSTRACT FROM AUTHOR]

Alternating‐rich copolymer of vinylboronic acid pinacol ester (VBpin) and maleic anhydride (MAH) was found to catalyze direct dehydrative esterification of carboxylic acid and alcohol. The key to the catalytic function is the activation of the MAH unit by the neighboring Lewis acidic boron directly connected to the backbone through the formation of five‐membered ring. The effects of the side‐chain cooperation were clarified through comparisons with the polymers having similar structures and a conventional titanium catalyst as well as the analyses of reactions with carboxylic acid or alcohol. The catalytic activity was enhanced as the molecular weight was higher, which is owing to the structural feature that boron is directly attached to the backbone. The cooperative catalysis is of interest because of its conceptual similarity with enzyme. [ABSTRACT FROM AUTHOR]

Molecules bearing carboxylic acid, amide, and hydroxyl groups are ubiquitous in crystal engineering, where robust hydrogen‐bonded synthons centred on these functionalities enable reliable crystal structure design. We now show that halogen bonding to the carbon π‐system of such molecules, traditionally ignored in crystal engineering, permits the recognition and directional assembly of the resulting hydrogen‐bonded structural subunits, leaving the archetypal hydrogen‐bonded ring, ladder, and chain homosynthons intact, but repositioned in space. When applied to heteromolecular synthons, this enables rearranging more complex hydrogen‐bonded motifs and the evolution of binary cocrystals into ternary ones through "latent" carbon‐based recognition sites, demonstrating a rational approach to build higher‐order solid‐state supramolecular assemblies. [ABSTRACT FROM AUTHOR]

Thioesters are important in synthesis, materials science, and biology, and their preparation traditionally relies on the use of disagreeable thiols. Here, we report a thiol‐free protocol that stitches together widespread carboxylic acids and aryl halides, producing a diverse array of thioesters. Crucial to this strategy is the discovery that tetramethylthiourea can serve as both a sulfur source and, upon direct excitation by purple light, as a strong reductant, suitable for activating aryl halides via single‐electron transfer. Coupling of the resulting aryl radicals provides an isothiouronium ion intermediate, which can be attacked by carboxylic acids via a polar pathway, affording the thioester products under mild conditions. [ABSTRACT FROM AUTHOR]

The photoinduced decarboxylative radical cascade alkylation/cyclization strategy of diverse benzimidazoles containing unactivated alkene moieties towards the synthesis of polycyclic benzimidazoles via ligand-to-metal-charge-transfer (LMCT) has been developed. Specifically, the reaction initiates the decarboxylation of alkyl carboxylic acids through light-induced charge transfer from the ligand to iron, resulting in the formation of alkyl radical centers. Moreover, the protocol has prominent features, such as a broad substrate scope, high regioselectivity, mild reaction conditions, operational simplicity and readily available air acting as the sole oxidant. [ABSTRACT FROM AUTHOR]

The separation and purification of bio-based chemicals from conversion processes often contribute substantially to bioprocessing costs, and for many biochemicals produced through fermentation, solventbased liquid--liquid extraction (LLE) is a common separations strategy for in situ product recovery (ISPR). Many in situ LLE-based separations for biochemicals are often challenged by emulsion formation between the immiscible aqueous and organic phases. Typically, membrane contactors have been used to overcome emulsion formation, with the aqueous and organic phases coming into contact in the membrane contactor pores, but these unit operations require a large membrane area to compensate for their limited effective interfacial area. In this study, we show that a hydrophobic polytetrafluoroethylene (PTFE) membrane-based emulsion separator (MBES) enables continuous LLE for the recovery of an exemplary fermentation product, butyric acid, with substantially improved throughput relative to a membrane contactor. With a membrane permeate flux of 290 L m-2 h-1, the overall butyric acid flux of the single-stage MBES system was calculated to be 1450 g m-2 h-1, which is substantially higher than the 9 g m-2 h-1 achievable with a membrane contactor. At an equivalent butyric acid throughput, process modeling estimates that MBES-assisted LLE can enable a 55% and 91% reduction in process costs (the sum of CAPEX and OPEX) and greenhouse gas emissions, respectively, compared to a membrane contactor due to a ~160-fold decrease in the required membrane area. Although membrane fouling from cellular debris led to reduced membrane flux and phase separation efficiency, common fouling mitigation strategies including the incorporation of ultrafiltration and periodic membrane backwashing effectively recovered the membrane performance. Overall, MBES systems can potentially enable continuous LLE processes in bioprocessing separations, including where emulsion formation is a challenge. [ABSTRACT FROM AUTHOR]

1.Challenges, strategies and new technologies in the field of biotransformation were presented and discussed at the 5th European Biotransformation Workshop, which was held on March 14, 2024 on the Novartis Campus in Basel, Switzerland.2. In this meeting report we summarise the presentations and discussions from this workshop.3. The topics covered are listed below:Advances in understanding drug induced liver injury (DILI) risks of carboxylic acids and targeted covalent inhibitorsBiotransformation of oligonucleotide-based therapeutics including automated software tools for metabolite identificationRecent advances in metabolite synthesisQualification and validation of a new compact Low Energy Accelerator Mass Spectrometry (LEA) system for metabolite profiling Advances in understanding drug induced liver injury (DILI) risks of carboxylic acids and targeted covalent inhibitorsBiotransformation of oligonucleotide-based therapeutics including automated software tools for metabolite identificationRecent advances in metabolite synthesisQualification and validation of a new compact Low Energy Accelerator Mass Spectrometry (LEA) system for metabolite profiling [ABSTRACT FROM AUTHOR]

Background: Benzyl acetate is an aromatic ester with a jasmine scent. It was discovered in plants and has broad applications in food, cosmetic, and pharmaceutical industries. Its current production predominantly relies on chemical synthesis. In this study, Escherichia coli was engineered to produce benzyl acetate. Results: Two biosynthetic routes based on the CoA-dependent β-oxidation pathway were constructed in E. coli for benzyl acetate production. In route I, benzoic acid pathway was extended to produce benzyl alcohol by combining carboxylic acid reductase and endogenous dehydrogenases and/or aldo-keto reductases in E. coli. Benzyl alcohol was then condensed with acetyl-CoA by the alcohol acetyltransferase ATF1 from yeast to form benzyl acetate. In route II, a plant CoA-dependent β-oxidation pathway via benzoyl-CoA was assessed for benzyl alcohol and benzyl acetate production in E. coli. The overexpression of the phosphotransacetylase from Clostridium kluyveri (CkPta) further improved benzyl acetate production in E. coli. Two-phase extractive fermentation in situ was adopted and optimized for benzyl acetate production in a shake flask. The most optimal strain produced 3.0 ± 0.2 g/L benzyl acetate in 48 h by shake-flask fermentation. Conclusions: We were able to establish the whole pathway for benzyl acetate based on the CoA-dependent β-oxidation in single strain for the first time. The highest titer for benzyl acetate produced from glucose by E. coli is reported. Moreover, cinnamyl acetate production as an unwanted by-product was very low. Results provided novel information regarding the engineering benzyl acetate production in microorganisms. [ABSTRACT FROM AUTHOR]

Photothermal anticancer therapy based on plasmonic nanoparticles is proposed to enhance treatment efficacy while mitigating unintended side effects. However, most studies blindly rely on the accumulation of nanoparticles at the tumor site, which may result in inefficient treatment. In this study, the aim is to evaluate relevant parameters to improve plasmonic photothermal therapy. Gold nanorods (AuNRs) with an optimized aspect ratio and either amino or carboxylic acid surface functionalization are selected as photothermal agents. AuNR biocompatibility and photothermal activity in 2D and 3D human MDA‐MB‐231 triple‐negative breast cancer cell models, evaluating localized hyperthermal cell death upon irradiation with resonant near‐infrared (NIR) light, are analyzed first. To ensure reliable tracking of biodistribution in vivo, AuNRs are labeled with the positron emitter copper‐64 (64Cu), and their distribution in a murine MDA‐MB‐231 tumor model is studied via positron emission tomography (PET) imaging. PET images reveal enhanced tumor accumulation of carboxylic acid‐functionalized AuNRs compared to amino‐functionalized AuNRs post‐intravenous administration. Relatively low NIR laser power densities (0.5 W cm−2) are used for controlled heating – keeping local temperature below 50 °C – upon irradiation of intravenously and intratumorally administered AuNRs. As a result, tumor growth is significantly decelerated, even 9 days after application of photothermal therapy. [ABSTRACT FROM AUTHOR]

An improved practical and efficient procedure for the synthesis of non-racemic unnatural α-amino acids through a stereocontrolled rearrangement is reported. Carboxylic acids are converted into azanyl esters RCO2 NHBoc followed by an iron-catalyzed 1,3-nitrogen migration to provide non-racemic α-amino acids in an asymmetric (α-monosubstituted α-amino acids) or enantioconvergent fashion (α,α-disubstituted α-amino acids). Under optimized conditions using a fluorinated chiral iron catalyst and 2,2,6,6-tetramethylpiperidine as the base in a solvent mixture of 1,2-dichlorobenzene and CHCl3 , enantioselectivities of up to 98% ee were obtained. Such high ee values are important for practical purposes, allowing the direct use of many of the obtained N-Boc-protected α-amino acids for subsequent applications. [ABSTRACT FROM AUTHOR]

The electrochemical reduction of CO2 (ERCO2) to valuable chemicals such as acetic acid/acetate offers a promising route to revolutionize chemical production and enhance sustainability. Here, we report the hydrothermal preparation of an electrocatalyst consisting of copper/titanium dioxide/reduced graphene oxide (Cu‐TiO2/rGO) for ERCO2 in aqueous medium. The metal‐support (TiO2/rGO) was pre‐synthesized by combining an aqueous solution of TiO2 and GO in an autoclave at 150 °C for 20 h. Then TiO2/rGO was added to synthesized Cu colloid formed through the reduction of copper (II) nitrate trihydrate resulting in the formation of Cu‐TiO2/rGO. The Cu‐TiO2/rGO hybrid nanocomposite was fully characterized using spectroscopic and microscopic techniques. This study explored the versatility of the rotating ring‐disc electrode (RRDE) as an in situ electroanalytical tool for the selective detection of products formed during ERCO2. The well‐designed hybrid electrocatalyst, containing Cu0/Cu+ active sites, facilitated the eight‐electron transfer for acetic acid (AA) formation at low potentials. AA formation was detected on the RRDE and validated by conventional NMR and HPLC techniques. This work highlights and expands the scope of selective hydrogenation of CO2 towards value‐added products. [ABSTRACT FROM AUTHOR]

Poly- and perfluoroalkyl substances (PFASs) have attracted great scientific attention because of their environmental persistence, bioaccumulation potentials, and toxicity. This study validated a simple and efficient sample preparation method for determining extractable PFASs, including 12 perfluoroalkyl carboxylic acids and 4 perfluoroalkyl sulfonates. The samples underwent ultrasonic extraction, and the extracts were cleaned up by dispersive solid-phase extraction technique with graphitized carbon if necessary. PFAS quantification was performed by a liquid chromatography-tandem mass spectrometry system. The instrument provided analytical signals for all target compounds with good repeatability (RSD < 15%), reproducibility (RSD < 20%), linearity (R2 > 0.99), and low detection limits (0.10–1.0 ng/mL). The validated method exhibited adequate recovery (70–115%), precision (RSD < 15%), and method detection limits (0.020–0.70 ng/g). This validated method was applied to analyze PFASs in several food packaging samples collected in Vietnam, showing very low levels (range 0.090–2.9 ng/g; median 0.72 ng/g) derived from unintentional sources. [ABSTRACT FROM AUTHOR]

Perfluorononanoic acid (PFNA) is a commercially relevant, long-chain (8 fully fluorinated carbon) perfluorinated carboxylic acid. PFNA has limited terrestrial ecotoxicity data and is detected in humans, animals, and the environment. This study is the fourth in a series with the objective of investigating the toxicity of a suite of per- and polyfluoroalkyl substances (PFAS) detected on military installations in a mammal indigenous to North America. Peromyscus leucopus (white-footed mice, ∼25/sex/dose) were exposed via oral gavage to either 0, 0.03, 0.14, 1, or 3 mg PFNA/kg-d for 112 consecutive days (4 wk premating exposure followed by an additional 12 wk of exposure after onset of mating). Parental generation animals were assessed for potential reproductive and developmental effects, organ weight changes, thyroid modulation, and immunotoxicity. Pup weight and survival were assessed at postnatal days 0, 1, 4, 7, and 10. Change in liver weight was determined to yield the most sensitive dose response according to benchmark dose analysis, and serves as the most protective point of departure (BMDL = 0.37 mg/kg-d PFNA). Other effects of PFNA exposure included reduced formation of plaque-forming cells, which are indicative of functional immune deficits (BMDL = 2.31 mg/kg-d); decreased serum thyroxine (BMDL = 0.93 mg/kg-d) without changes in some other hormones; and increased stillbirths (BMDL = 0.61 mg/kg-d PFNA). Pup weight and survival were not affected by PFNA exposure. Combined with data from previous studies, data from Peromyscus provide a One Health perspective on health effects of PFAS. [ABSTRACT FROM AUTHOR]

In this study, we report the fabrication and characteristics of a self-healing polymer forming an ionically bonded network based on carboxylic acids and alkyl amines. The self-healing polymer forming an ionically bonded network is prepared from acrylic acid-containing carboxylic groups in the main chain and ammonium carboxylate salts derived from alkyl amines of varying lengths. The nature of the ion bonding between alkyl amines and carboxylic acids within the polymer matrix was analyzed using Nuclear Magnetic Resonance (NMR) and Fourier Transform Infrared Spectroscopy (FT-IR). The self-healing polymer, incorporating ionically bound entities like ammonium carboxylate salts, demonstrated 100% self-healing efficiency at room temperature overnight, in contrast to the reference polymer without ion bonding. Various lengths of alkyl amines used to form ammonium carboxylate salts exhibited remarkable properties such as over 500% elongation at break, adhesive strength exceeding 300 gf, and light transmittance of over 90%, all dependent on the length of the alkyl chain. [ABSTRACT FROM AUTHOR]

In this study, Pd nanoparticles encapsulated in the copper‐based mesoporous metal–organic framework (Cu2(BDC)2DABCO) and used as a reusable heterogeneous catalyst to establish a method for the direct benzylation of carboxylic acids through C‐H (sp3) bond activation. The catalyst structure was characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), X‐ray diffraction (XRD), Brunauer–Emmett–Teller (BET), and inductively coupled plasma (ICP). This catalyst showed high catalytic activity, selectivity, and good functional group tolerance for the direct benzylation of carboxylic acids. [ABSTRACT FROM AUTHOR]

In this reported work, bioscoured and bleached cotton fabrics were treated with three different polycarboxylic acids, i.e., malic acid, citric acid, and 1,2,3,4-butane tetracarboxylic acids. The presence of carboxylic acids on the fabric surface as well as the changes in the crystalinity index was determined by Fourier transform Infrared spectroscopy and X-ray diffraction analysis. The carboxylic acids treated fabrics were analyzed for their physico-mechanical as well as comfort properties such as tensile strength, elongation, stiffness, air permeability, abrasion resistance, drape, water absorption, and wicking. The results inferred that the polycarboxylic acid-treated cotton showed improved drapability, wrinkle recovery, and strength up to 7% concentration; afterward, it started deteriorating. Weight loss due to abrasion was found to decrease with the addition of crosslinkers. A minor improvement in wicking and wetting properties was also noticed. [ABSTRACT FROM AUTHOR]

A simple and green method for the recovery of methyl methacrylate (MMA) has been developed by recycling waste sheets of poly-(methyl methacrylate) without using any catalyst. The liquefaction yield was 97.33% while the purity of recovered MMA was up to 92%. The recovered monomer utilized for the synthesis of methylmethacrylate-copolymer-divinylbenzene at 20% cross-linking in the presence of different porogens (methyl isobutyl ketone, cyclohexane, toluene, and cyclohexanone) by suspension polymerization. The same copolymer was also synthesized but with different cross-linking percentages such as 4, 10, 15, 20, 25, 30, and 40% in the presence of a single porogen (methyl isobutyl ketone). Different copolymers having pore volumes in the range of 0.120–0.682 mL/g were obtained. The pendant –COOCH3 groups within the polymeric chain were converted to –COOH groups via acid hydrolysis, accompanied by the attachment of –SO3H groups to phenyl rings. ATR-FTIR, UV–Vis spectrometry, and HPLC techniques were used for qualitative and quantitative analyses of –COOH and –SO3H groups. The obtained results were compared with copolymers and resin synthesized using commercial MMA, displaying similar behavior. The resin derived from the recovered monomer was utilized for Co2+ ion removal at various pH, demonstrating excellent removal performance. [ABSTRACT FROM AUTHOR]

Three crystalline organic salts (melamine)2: (itaconic acid): 3H2O [(Hmem)22+·(itca2−)·(H2O)3, itca2− = itaconate] (1), (melamine)2:(2-bromo-but-2-enedioic acid):DMF:2H2O [(Hmem+)2·(bbda2−)·DMF·(H2O)2, bbda2− = 2-bromo-but-2-enedioate] (2) and (melamine):(α-ketoglutaric acid) [(Hmem+)·(Hketglua−), Hketglua− = hydrogen α-ketoglutarate] (3) were featured by X-ray diffraction analysis, IR, mp, and elemental analysis. Significant non-covalent interactions were calculated by means of the Hirshfeld surface analysis. All salts involve extensive N–H···OH-bonds as well as other non-covalent associations. The melamine polymers/dimers were set up at 1–2/3 by the pair of complmentary N–H···NH-bonds. The role of these non-covalent interactions in the crystal packing is ascertained. These weak interactions combined, all salts exhibited 3D framework motifs. The crystal structures of the salts from melamine, itaconic acid, 2-bromo-but-2-enedioic acid and α-ketoglutaric acid are predominantly stabilized by the classical hydrogen bonds as well as CH2···O, CH3···O, Br···Br, C···C, O···C, and π···π interactions. [ABSTRACT FROM AUTHOR]

Organic conjugated carboxylic acids are promising anodes for lithium‐ion batteries (LIBs) owing to their high specific capacity, design flexibility, and environmental friendliness. Unfortunately, similar to polysulfides, organic conjugated carboxylic acid materials and their redox intermediates suffer from poor intrinsic electronic conductivity, severe dissolution issues, and the resulting shuttle effect, thereby giving rise to rapid capacity decay and poor cycling stability. Herein, a SiO2 template‐assisted pyrolysis strategy is developed to prepare nitrogen‐doped hollow porous carbon bowls (N‐HPCB) as highly efficient hosts for organic conjugated carboxylic acids (maleic acid, MA). Benefiting from the large specific surface area, rational pore structure, and numerous nitrogen defect sites, N‐HPCB can remarkably suppress the dissolution of MA and its redox intermediates (LixMA) through both physical confinement and chemical bonding and facilitate the LixMA conversion. With these merits, the MA@HPCB electrodes deliver a high reversible specific capacity of 1134.9 mAh g−1 at 0.1 A g−1, exceptional long‐term cyclability (retaining 328.8 mAh g−1 at 5 A g−1 after 985 cycles), and outstanding rate capability (189.1 mAh g−1 at 10 A g−1). Thus, the work provides a new approach to achieving a high‐rate and highly stable organic conjugated carboxylic acid materials. [ABSTRACT FROM AUTHOR]

β‐Chiral carboxylic acids and their derivatives are highly valuable structural motifs in the fields of asymmetric synthesis and medicinal chemistry. However, the introduction of a sterically demanding sidechain to the β‐carbon, such as an all‐carbon quaternary center, remains a significant challenge in classical polar processes. Recently, N‐heterocyclic carbene (NHC) mediated coupling reactions involving persistent ketyl radicals have emerged as a promising strategy to assemble highly crowded carbon‐carbon bonds. Nevertheless, achieving enantioselectivity in these reactions remains highly challenging. In this work, we report our recent progress in controlling enantioselectivity for relay coupling of perfluoroalkyl and persistent vinylogous ketyl radicals. We developed a chiral bifunctional NHC‐squaramide catalyst that achieves high facial selectivity in a critical bond‐forming event involving the coupling of a congested tertiary carbon radical and vinylogous ketyl radical. Chiral carboxylates bearing an all‐carbon quaternary center at the β‐position can be prepared in good yield and excellent enantiomeric excess. Results from density functional theory (DFT) calculations and nuclear Overhauser effect (NOE) experiments indicate that the N,N'‐diaryl squaramide motif adopts an unusual syn‐syn conformation, enabling hydrogen bonding interactions with the enolate oxygen, thereby rigidifying the overall conformation of the transition state. [ABSTRACT FROM AUTHOR]

We report herein a blue‐light‐promoted iron‐catalyzed reduction of carboxamides and carboxylic esters. Conducting the reaction under hydrosilylation conditions and blue light (2×24 W, 450–460 nm) in the presence of an iron(0) based pre‐catalyst, Fe(CO)4(IMes), amines and alcohols were obtained, respectively, notably at ambient conditions, whereas using white light, higher reaction temperatures up to 100 °C were required. Preliminary mechanism studies highlighted the crucial role of blue light not only to generate the catalytic active species, but also in some steps of the catalytic cycle. [ABSTRACT FROM AUTHOR]

We report an electrochemically promoted decarboxylation of readily available carboxylic acid and subsequent Mumm rearrangement to synthesize the corresponding imides. The reaction features external oxidant‐free, transition metal‐free mild conditions, and good functional group tolerance, affording various imides in moderate to good yields. Mechanistic studies reveal that the selective oxidation of aliphatic carboxylic acids appears to be the key step in this transformation. [ABSTRACT FROM AUTHOR]

ABSTRACT In this study, an efficient catalytic protocol using CuCoFe2O4@GO (CCF@GO) for the synthesis of amide bond (−CONH−) via direct coupling of carboxylic acids and N,N‐dialkylformamides is presented. The CCF@GO nanocatalyst has been synthesized via a single‐pot solvothermal method, by changing the proportions of copper and cobalt (1:1, 1:3, and 3:1). Catalyst screening, employing a model reaction with benzoic acid and dimethylformamide (DMF), revealed that the 1:1 proportion of CCF@GO catalyst exhibited excellent efficiency, achieving a high conversion (98%) towards amide formation. The enhanced catalytic efficiency observed in CCF@GO catalysts can be ascribed to the uniform distribution of active copper and cobalt species on the graphene oxide support, which possesses a high surface area. Optimization of the reaction was conducted by varying parameters such as temperature, solvent, catalyst loading, and oxidant. The prepared catalyst was characterized using various analytical techniques including XRD, FTIR, XPS, SEM, EDX mapping, and TEM. Furthermore, this heterogeneous nanocatalyst demonstrated recoverability using an external magnet and reused up to five times with just a modest loss of catalytic performance. [ABSTRACT FROM AUTHOR]

ABSTRACT Five new lanthanide complexes {[Sm(H2L)(H2O)4(Cl)]⋅H2O⋅Cl}n (1), {[Eu(H2L)(H2O)4Cl]⋅Cl}n (2), {[La(H2L)(H2O)4Cl]⋅Cl}n (3), {[Pr(H2L)(H2O)4Cl]⋅Cl}n (4), {[Ce(H2L)(H2O)4Cl]⋅Cl}n (5) (H3L = 2‐hydroxy‐5‐(5‐(hydroxy‐λ2‐methoxy)‐1H‐benzo[d]imidazole‐5‐carboxylic acid) were successfully synthesized under solvothermal method. 1 exhibits a two‐dimensional (2D) network structure, whereas 2–5 feature one‐dimensional (1D) chain structure. The fluorescence investigations demonstrated that 1–5 could be the fluorescent sensor for nitrobenzene (NB) and Fe(III) ions with high selectivity, sensitivity, and low detection limits. Furthermore, 1–5 displayed the good adsorption to anionic dye Congo red (CR), and the adsorption capacities were 140.5, 206.5, 212.5, 111.5, and 211.5 mg·g−1, respectively. [ABSTRACT FROM AUTHOR]

Background: Spinal muscular atrophy (SMA) is a neurodegenerative disorder. Although prior studies have investigated the metabolomes of SMA in various contexts, there is a gap in research on cerebrospinal fluid (CSF) metabolomics compared to healthy controls. CSF metabolomics can provide insights into central nervous system function and patient outcomes. This study aims to investigate CSF metabolite profiles in untreated SMA patients to enhance our understanding of SMA metabolic dysregulation. Methods: This case control study included 15 SMA patients and 14 control subjects. CSF samples were collected, and untargeted metabolomics was conducted to detect metabolites in SMA and control groups. Results: A total of 118 metabolites abundance were significantly changed between the SMA and control groups. Of those, 27 metabolites with variable importance for the projection (VIP) ≥ 1.5 were identified. The top 5 differential metabolites were N-acetylneuraminic acid (VIP = 2.38, Fold change = 0.43, P = 5.49 × 10–5), 2,3-dihydroxyindole (VIP = 2.33, Fold change = 0.39, P = 1.81 × 10–4), lumichrome (VIP = 2.30, Fold change = 0.48, P = 7.90 × 10–5), arachidic acid (VIP = 2.23, Fold change = 10.79, P = 6.50 × 10–6), and 10-hydroxydecanoic acid (VIP = 2.23, Fold change = 0.60, P = 1.44 × 10–4). Cluster analysis demonstrated that the differentially metabolites predominantly clustered within two main categories: protein and amino acid metabolism, and lipid metabolism. Conclusions: The findings highlight the complexity of SMA, with widespread effects on multiple metabolic pathways, particularly in amino acid and lipid metabolism. N-acetylneuraminic acid may be a potential treatment for functional improvement in SMA. The exact mechanisms and potential therapeutic targets associated with metabolic dysregulation in SMA require further investigation. [ABSTRACT FROM AUTHOR]

The utilization of low‐energy sunlight to produce renewable fuels is a subject of great interest. Here we report the first example of metal chalcogenide quantum dots (QDs) capped with a pyridinethiolate carboxylic acid (pyS‐COOH) for red‐light‐driven H2 production in water. The precious‐metal‐free system is robust over 240 h, and achieves a turnover number (TON) of 43910±305 (vs Ni) with a rate of 31570±1690 μmol g−1 h−1 for hydrogen production. In contrast to the inactive QDs capped with other thiolate ligands, the CdSe‐pyS‐COOH QDs give a significantly higher singlet oxygen quantum yield [ΦΔ (1O2)] in solution. [ABSTRACT FROM AUTHOR]

A formal [4+3] cycloaddition of 2‐alkylidenetrimethylene carbonates with quinazoline‐derived azomethine imines is described. Under Pd catalysis, the reaction works efficiently under room temperature to afford angular quinazoline‐fused seven‐membered N,N,O‐heterocycles. A variety of cyclic carbonates and azomethine imines were well tolerated under mild reaction conditions. This work demonstrates the synthetic utility of decarboxylative cycloadditions of 2‐alkylidenetrimethylene carbonates for the synthesis of angular polycyclic aromatic molecules. [ABSTRACT FROM AUTHOR]

Catalytic transformation of renewable biomass into value-added chemicals is an appealing strategy to upgrade biomass resources. Due to the presence of abundant oxygen-containing groups such as hydroxyl and aldehyde, biomass and its derived platform molecules have been served as ideal starting feedstock to synthesize valuable N-containing chemicals through reductive amination. In this mini review, we overviewed the recent advances in the reductive amination of several key bio-platform molecules including hydroxyl carboxylic acids, furfural, 5-hydroxylmethyl furfural and levulinic acid, with a focus on the production of amino acids, furan amines and pyrrolidones using thermocatalysis, electrocatalysis or photocatalysis. Moreover, the functions of active sites and the reaction mechanisms in different catalytic systems are discussed to get insights into the key factors in the reductive amination of biomass resources. [ABSTRACT FROM AUTHOR]

S-Adenosyl-L-methionine (SAM)-mediated methylation of biomolecules controls their function and regulates numerous vital intracellular processes. Analogs of SAM with a reporter group in place of the S-methyl group are widely used to study these processes. However, many of these analogs are chemically unstable that largely limits their practical application. We have developed a new compound, SAM-Ph, which contains an H-phosphinic group (-P(O)(H)OH) instead of the SAM carboxylic group. SAM-PH is significantly more stable than SAM, retains functional activity in catechol-O-methyltransferase and methyltransferase WBSCR27 reactions. The last is associated with Williams-Beuren syndrome. Rac-SAM-PH was synthesized chemically, while (R,S)-SAM-PH and its analogs were prepared enzymatically either from H-phosphinic analogs of methionine (Met-PH) or H-phosphinic analog of S-adenosyl-L-homocysteine (SAH-Ph) using methionine adenosyltransferase 2A or halide methyltransferases, respectively. SAH-PH undergoes glycoside bond cleavage in the presence of methylthioadenosine nucleosidase like natural SAH. Thus, SAM-PH and its analogs are promising new tools for investigating methyltransferases and incorporating reporter groups into their substrates. [ABSTRACT FROM AUTHOR]

Polyethylene terephthalate has been widely used in the packaging industry. Degraded PET micro(nano)plastics could pose public health concerns following release into various environments. This study focuses on PET degradation under ultraviolet radiation using the NIST SPHERE facility at the National Institute of Standards and Technology in saturated humidity (i.e., ≥95% relative humidity) and dry conditions (i.e., ≤5% relative humidity) with varying temperatures (30 °C, 40 °C, and 50 °C) for up 20 days. ATR-FTIR was used to characterize the chemical composition change of degraded PET as a function of UV exposure time. The results showed that the cleavage of the ester bond at peak 1713 cm−1 and the formation of the carboxylic acid at peak 1685 cm−1 were significantly influenced by UV radiation. Furthermore, the formation of carboxylic acid was considerably higher at saturated humidity and 50 °C conditions compared with dry conditions. The ester bond cleavage was also more pronounced in saturated humidity conditions. The novelty of this study is to provide insights into the chemical degradation of PET under environmental conditions, including UV radiation, humidity, and temperature. The results can be used to develop strategies to reduce the environmental impact of plastic pollution. [ABSTRACT FROM AUTHOR]

The development of robust and reliable methods for the construction of C(sp2)−C(sp3) bonds is vital for accessing an increased array of structurally diverse scaffolds in drug discovery and development campaigns. While significant advances towards this goal have been achieved using metallaphotoredox chemistry, many of these methods utilise photocatalysts based on precious‐metals due to their efficient redox processes and tuneable properties. However, due to the cost, scarcity, and toxicity of these metals, the search for suitable replacements should be a priority. Here, we show the use of commercially available heterogeneous semiconductor graphitic carbon nitride (gCN) as a photocatalyst, combined with nickel catalysis, for the cross‐coupling between aryl halide and carboxylic acid coupling partners. gCN has been shown to engage in single‐electron‐transfer (SET) and energy‐transfer (EnT) processes for the formation of C−X bonds, and in this manuscript we overcome previous limitations to furnish C−C over C−O bonds using carboxylic acids. A broad scope of both aryl halides and carboxylic acids is presented, and recycling of the photocatalyst demonstrated. The mechanism of the reaction is also investigated. [ABSTRACT FROM AUTHOR]

A dearomative oxidation of pyrroles to Δ3‐pyrrol‐2‐ones is described, which employs a sulfoxide as oxidant, in conjunction with a carboxylic acid anhydride and a Brønsted acid additive. 3‐substituted pyrroles undergo regioselective oxidation to give the product isomer in which oxygen has been introduced at the more hindered position. Regioselectivity is rationalized by a proposed mechanism that proceeds by initial thianthrenium introduction at the less‐hindered pyrrole α‐position, followed by distal attack of an oxygen nucleophile and subsequent elimination of thianthrene. The same reaction conditions are also able to effect a chemoselective oxidation of indoles to indolin‐3‐ones and additionally of indolin‐3‐ones to 2‐hydroxyindolin‐3‐ones. Here again, the regio‐ and chemoselectivities are rationalized through the intermediacy of a thianthrenium salt. [ABSTRACT FROM AUTHOR]

gem‐Diborylalkanes are highly valuable building blocks in organic synthesis and pharmaceutical chemistry due to their ability to participate in multi‐step cross‐coupling transformations, allowing for the rapid generation of molecular complexity. While progress has been made in their synthetic metholodology, the construction of β‐tertiary and C(sp3)‐rich gem‐diborylalkanes remains a synthetic challenge due to substrate limitations and steric hindrance issues. An approach is presented that utilizes synergistic photoredox and copper catalysis to achieve efficient C(sp3)−C(sp3) cross‐coupling of alkyl N‐hydroxyphthalimide esters, which can easily be obtained from alkyl carboxylic acids, with diborylmethyl species, providing a series of C(sp3)‐rich gem‐diborylalkanes with 1°, 2°, and even 3° β positions. Furthermore, this approach can also be applied to complex medicinal compounds and natural products, offering rapid access to molecular complexity and late‐stage functionalization of C(sp3)‐rich drug candidates. Mechanistic experiments revealed that diborylmethyl Cu(I) species participated in both the photoredox process and the key C(sp3)−C(sp3) bond‐forming step. [ABSTRACT FROM AUTHOR]

A new stereodivergent one‐pot tandem protocol, which granted diastereo‐ and enantioselective access to chiral aldols by starting from simple primary alcohols, is presented as a proof‐of‐concept. The synergistic combination of a chemoselective Cu(II)‐catalyzed oxidation of primary alcohols into the corresponding aldehydes (without the expected overoxidation into the corresponding carboxylic acids and using simple aerial O2 as co‐oxidant), followed by a concomitant organocatalyzed enantioselective aldol coupling promoted by the system (S)‐proline/HTBD‐BF4 [TBD=1,5,7‐triazabicyclo[4.4.0]dec‐5‐ene], was achieved after fine‐tuning and compatibilizing the conditions required for the successful performance of both catalytic systems. Here, we demonstrated that selection and pairing of both catalysts needs to be extremely judicious to avoid orthogonality, kinetic, concentration or reciprocal poisoning issues. Refinement of the overall tandem protocol allowed us to design a synergistic and stereodivergent protocol which affords comparable or even better diastereoselective results than the organocatalytic system by itself. Finally, the following key factors (from a sustainable point of view) should be highlighted: i) no external VOC solvents are needed during our one‐pot tandem synthetic protocol (by working under neat conditions); and ii) isolation/purification of any intermediate is not required, thus reducing the chemical waste and energy/time costs, simplifying the practical aspects of our synthetic methodology. [ABSTRACT FROM AUTHOR]

Catalytic hydrogenation of carbon dioxide (CO2) for the preparation of higher carboxylic acids is attractive and promising. Herein, we demonstrate a general strategy for producing higher carboxylic acids via reaction of CO2 and H2 with light (C2~C4) oxygenates such as ketones, alcohols, polyols, ethers and epoxides. In a green solvent consisting of ionic liquid (1‐ethyl‐3‐methylimidazolium iodide) and water, the reaction can be efficiently accelerated by RhI3 catalyst and I2 promoter at 170 °C. Very high or remarkable yields of higher carboxylic acids were synthesized via C−C bond formation between the intermediates generated from the oxygenates and CO2. Detailed study indicated that the catalyst and the solvent had excellent synergistic effect for promoting the reaction. The strategy can effectively convert the bulk and inexpensive feedstocks to value‐added carboxylic acids, and therefore is promising for commercial application. [ABSTRACT FROM AUTHOR]

Protein–peptide-based materials typically possess high nutritional value and various physiological regulatory activities. This study evaluated the digestion, metabolism, and activity of Stropharia rugosoannulata protein–peptide-based materials. After the S. rugosoannulata protein–peptide-based materials were digested (simulated) orally, in the stomach, and in the intestines, the proportions of >10,000 Da, 5000~10,000 Da, and <180 Da in the digestion products increased, and the peptide content was maintained at more than 120 mg/g dry weight. The digestion products of eight test groups with different oral–gastrointestinal digestion-level settings all had suitable ACE inhibitory activity (IC50 range 0.004~0.096 mg/mL). The main metabolite groups were lipid-like molecules, fatty acids, carboxylic acids, their derivatives, amino acids, peptides, and analogs. Bile and glycosylated amino acids were the main compounds that caused differences between groups. KEGG pathways enriched in differentially expressed metabolites included eight significantly upregulated pathways, including valine, leucine, and isoleucine biosynthesis, etc., and six significantly downregulated pathways, including the citric acid cycle (tricarboxylic acid cycle), etc. The arginine and proline metabolism pathways and the aminoacyl-tRNA biosynthesis pathways were upregulation and downregulation pathways that enriched multiple differentially expressed metabolites. Twenty-six metabolites, including bile acids, total bile acids, and the essential amino acids L-isoleucine and L-leucine, were differentially expressed metabolite markers of the protein–peptide-based material oral–gastrointestinal digestion products. [ABSTRACT FROM AUTHOR]

Catalytic hydrogenation of carbon dioxide (CO2) for the preparation of higher carboxylic acids is attractive and promising. Herein, we demonstrate a general strategy for producing higher carboxylic acids via reaction of CO2 and H2 with light (C2~C4) oxygenates such as ketones, alcohols, polyols, ethers and epoxides. In a green solvent consisting of ionic liquid (1‐ethyl‐3‐methylimidazolium iodide) and water, the reaction can be efficiently accelerated by RhI3 catalyst and I2 promoter at 170 °C. Very high or remarkable yields of higher carboxylic acids were synthesized via C−C bond formation between the intermediates generated from the oxygenates and CO2. Detailed study indicated that the catalyst and the solvent had excellent synergistic effect for promoting the reaction. The strategy can effectively convert the bulk and inexpensive feedstocks to value‐added carboxylic acids, and therefore is promising for commercial application. [ABSTRACT FROM AUTHOR]