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Gelsemium sempervirens (L.) J.St.-Hil. is an evergreen shrub occurring naturally in North and Middle America. So far, more than 120 alkaloids have been identified in this plant in addition to steroids, coumarins and iridoids, and its use in traditional medicine has been traced back to these compound classes. However, a comprehensive phytochemical investigation of the plant with a special focus on further compound classes has not yet been performed. Therefore, the present study aimed at an extensive HPLC-MSn characterization of secondary metabolites and, for the first time, reports the occurrence of various depsides and phenolic glycerides in G. sempervirens roots and rhizomes, consisting of benzoic and cinnamic acid derivatives as well as dicarboxylic acids. Furthermore, mono- and disaccharides were assigned by GC-MS. Applying the Folin–Ciocalteu assay, the phenolic content of extracts obtained with different solvents was estimated to range from 30 to 50% calculated as chlorogenic acid equivalents per g dry weight and was related to the DPPH radical scavenging activity of the respective extracts. Upon lactic acid fermentation of aqueous G. sempervirens extracts, degradation of phenolic esters was observed going along with the formation of low-molecular volatile metabolites. [ABSTRACT FROM AUTHOR]

Plastic pollution is an emerging global threat due to lack of effective methods for transforming waste plastics into useful resources. Here, we demonstrate a direct oxidative upcycling of polyethylene into high‐value and high‐volume saturated dicarboxylic acids in high carbon yield of 85.9 % in which the carbon yield of long chain dicarboxylic (C10‐C20) acids can reach 58.9% over cobalt‐doped MCM‐41 molecular sieves, in the absence of any solvent or precious metal catalyst. The distribution of the dicarboxylic acids can be controllably adjusted from short‐chain (C4‐C10) to long‐chain ones (C10‐C20) through changing cobalt loading of MCM‐41 under nanoconfinement. Highly and sparsely dispersed cobalt along with confined space of mesoporous structure enables complete degradation of polyethylene and high selectivity of dicarboxylic acid in mild condition. So far, this is the first report on highly selective one‐step preparation of long chain dicarboxylic acids. The approach provides an attractive solution to tackle plastic pollution and a promising alternative route to long chain diacids. [ABSTRACT FROM AUTHOR]

Poly(ester amide)s (PEAs) attract much attention as a new kind of biodegradable polymers. However, the synthesis of PEAs with sequence-regulated chain structures is still complicated due to the multistep polymerization, high monomer purity, as well as the usage of organic solvents, which greatly inhibits its development and applications. Herein, a one-pot strategy without solvent was developed to synthesize the alternating PEA from α,ω-amino alcohol and dicarboxylic acid by sequential polycondensation, where water was used as the controlling agent for amidation and esterification. Specifically, the amidation and esterification were controlled to proceed in turn by adding or removing water, realizing the one-pot preparation of alternating PEAs. The resultant PEA is characterized by 1H- and 13C-NMR, and its chain structure is confirmed to be highly quasi-alternating similar to alternating PEAs prepared by classical methods The evaluations from DSC and DMA demonstrate that the properties of quasi-alternating PEA (Tm=102 °C, ΔHm=30 J·g−1) are far superior to those of random PEA (Tm=72 °C, ΔHm<1 J·g−1). [ABSTRACT FROM AUTHOR]

​​​​​​​Volatile organic compounds (VOCs) play a key role in tropospheric chemistry, giving rise to secondary products such as highly oxygenated organic molecules (HOMs) and secondary organic aerosols (SOAs). HOMs, a group of low-volatility gas-phase products, are formed through the autoxidation process of peroxy radicals (RO 2) originating from the oxidation of VOCs. The measurement of HOMs is made by a NO 3- ToFCIMS instrument, which also detects other species like small highly oxygenated VOCs (e.g., dicarboxylic acids) and sulfuric acid (H 2 SO 4). The instrument response to HOMs is typically estimated using H 2 SO 4 , as HOMs are neither commercially available nor easily synthesized in the laboratory. The resulting calibration factor is then applied to quantify all species detected using this technique. In this study, we explore the sensitivity of the instrument to commercially available small organic compounds, primarily dicarboxylic acids, given the limitations associated with producing known amounts of HOMs for calibration. We compare these single-compound calibration factors to the one obtained for H 2 SO 4 under identical operational conditions. The study found that the sensitivity of the NO 3- ToFCIMS varies depending on the specific type of organic compound, illustrating how a single calibration factor derived from sulfuric acid is clearly inadequate for quantifying all detected species using this technique. The results highlighted substantial variability in the calibration factors for the tested organic compounds, with 4-nitrocatechol exhibiting the highest sensitivity and pyruvic acid the lowest. The obtained sulfuric acid calibration factor agreed well with the previous values from the literature. In summary, this research emphasized the need to develop reliable and precise calibration methods for progressively oxygenated reaction products measured with a NO 3- chemical-ionization mass spectrometer (CIMS), for example, HOMs. [ABSTRACT FROM AUTHOR]

This study investigated the synthesis of α-hemihydrate gypsum (α-HH) through semiliquid autoclaving of phosphogypsum (PG) using various carboxylic acids as modifying agents. The impact of carboxyl group spatial location, auxiliary functional group type, and the number of carboxyl groups within the carboxylic acid modifiers on the mechanical strength and crystal morphology of α-HH was analyzed using scanning electron microscopy (SEM), strength testing, and molecular dynamics simulations. The results revealed a significant influence of the carboxylic acid molecular structure on the α-HH crystal morphology. Monocarboxylic acids and dicarboxylic acids with a long carbon chain length between carboxyl groups exhibited preferential adsorption on the (200), (110), and (-110) crystal planes, promoting crystal growth along the c-axis. In contrast, hydroxyl groups and cis double bonds in the modifier structure induced selective adsorption on the (001) plane, hindering growth along the c-axis. Conversely, trans double bonds favored adsorption on the (200), (110), and (-110) planes, enhancing growth along the c-axis. Based on these observations, screening principles for carboxylic acid modifiers were established, suggesting that: 1) the number of carboxyl groups should exceed 2; 2) the optimal carbon atom spacing between carboxyl groups is 3; and 3) auxiliary functional groups such as hydroxyl groups and cis double bonds should be introduced. Modifiers like citric acid, ethylene diamine tetraacetic acid (EDTA), and pyromellitic acid, within concentration ranges of 0.05%-0.1%, 0.1%-0.15%, and 0.05%-0.1%, respectively, yielded α-HH with flexural strengths exceeding 4 MPa and compressive strengths greater than 35 MPa, demonstrating the validity of these principles. [ABSTRACT FROM AUTHOR]

A series of novel salts based on aromatic polyamines and 2,3-pyrazinedicarboxylic acid, such as C10H12N6O5 (1), C10H9ClN6O4 (2), C11H10N8O4 (3), and C14H17N16O5.5 (4) or 3,4-thiophenedicarboxylic acid, such as C10H10N4O4S (5), C10H9ClN4O4S (6), and C10H10N4O4S2 (7), were synthesized and characterized by single-crystal X-ray diffraction. All compounds crystallize in a monoclinic space group. The structure was subjected to complex Hirshfeld surface analysis, molecular electrostatic potential, enrichment ratio, and energy framework calculations. The influence of different cations on the packing of 3-carboxypyrazine-2-carboxylate and 4-carboxythiophene-3-carboxylate anions in the crystal lattice was studied. O...H/H...O interactions are the main contributor in all crystals. In addition, in a series of pyrazine-containing structures, N(C)...H/H...N(C) interactions have relevance, while in a series of thiophene-based compounds, C...H/H...C and S...H(O)/H(O)...S. In addition, Cl-based interactions are observed in compound 2. According to the enrichment ratio calculations, O...H/H...O and C...C are the most preferable interactions in all structures. The energy frameworks are dominated by the dispersive contribution, only in compound 3 is the electrostatic term dominant. The analyzed structures reveal intra- and intermolecular recurrent supramolecular synthons. In both series of crystals, the robust H-bonded centrosymmetric dimer R22(8) as homo- or as heterosynthon (in compounds 2, 3, 6, and 7) and the intramolecular synthon S(7) generated by O-H...O interactions (in compounds 2, 6, and 7) are present. The supramolecular patterns formed by π...π (C...C) and C-O(Cl,S)...C are also noticeable. Notably, a dual synthon linking the supramolecular chain via π...π interactions and the homosynthon R22(8) via N-H...N interactions is visible in both series of new salts. A library of H-bonding motifs at diverse levels of supramolecular architecture is provided. We extended the analysis of intramolecular H-bonding motifs to similar structures deposited in the Cambridge Structural Database. Another important feature is the existence of an intramolecular O...H...O bridge between two neighboring carboxylic groups as substituents in anions in compounds 3 and 5. In this context, we performed quantum theory of atoms-in-molecule calculations to reveal more details. [ABSTRACT FROM AUTHOR]

In this study, crosslinked films of polyvinyl alcohol (PVA) were prepared using two dicarboxylic acids: saturated succinic acid (SA) and unsaturated maleic acid (MAL) as crosslinkers. The crosslinking capabilities of these acids were compared through physical, chemical, mechanical, morphological, thermal analysis, and swelling measurements to investigate their impact on the physicochemical properties of the resulting films. Attenuated total reflectance fourier transform infrared spectroscopy (FTIR) confirmed the occurrence of an esterification reaction between PVA and the dicarboxylic acids. Based on the degree of crosslinking and thermal properties, it was noted that the crosslinking achieved with maleic acid is more effective for PVA compared with succinic acid. The crosslinking degree of PVA‐MAL was determined to be 6.47 times higher than that of the PVA‐SA film. In terms of thermal stability, the decomposition temperature for crosslinked PVA‐MAL was measured at 365.57°C, whereas PVA‐SA exhibited a slightly lower decomposition temperature of 362.58°C. The findings indicate that the PVA‐MAL film displays lower crystallinity and a higher contact angle (80.60°) in contrast to PVA‐SA (76.0°) and PVA (30.4°). Atomic force microscopy analysis indicated that the PVA‐SA film exhibited more surface roughness compared with the smoother PVA‐MAL film. Also, crosslinked films displayed enhanced elasticity and resilience in comparison with neat PVA, which may be due to the difference in crosslinking density, disruption in intermolecular hydrogen bonding due to crosslinking, and incorporation of flexible crosslinkers. Highlights: PVA was crosslinked using SA and MAL.Unsaturated MAL exhibited superior crosslinking density over saturated SA.PVA‐SA film exhibited a porous surface compared to PVA‐MAL film.PVA crosslinked with unsaturated MAL showed higher thermal stability than SA.Both the films showed enhanced elasticity and resilience compared with neat PVA. [ABSTRACT FROM AUTHOR]

Biochemical systems make use of out‐of‐equilibrium polymers generated under kinetic control. Inspired by these systems, many abiotic supramolecular polymers driven by chemical fuel reactions have been reported. Conversely, polymers based on transient covalent bonds have received little attention, even though they have the potential to complement supramolecular systems by generating transient structures based on stronger bonds and by offering a straightforward tuning of reaction kinetics. In this study, we show that simple aqueous dicarboxylic acids give poly(anhydrides) when treated with the carbodiimide EDC. Transient covalent polymers with molecular weights exceeding 15,000 are generated which then decompose over the course of hours to weeks. Disassembly kinetics can be controlled using simple substituent effects in the monomer design. The impact of solvent polarity, carbodiimide concentration, temperature, pyridine concentration, and monomer concentration on polymer properties and lifetimes has been investigated. The results reveal substantial control over polymer assembly and disassembly kinetics, highlighting the potential for fine‐tuned kinetic control in nonequilibrium polymerization systems. [ABSTRACT FROM AUTHOR]

Thorium harms humans and the environment. Mining can release thorium‐containing waste. This study aims to simplify the production of a novel poly‐adsorbent by mixing pyridine dicarboxylic acid, polyvinyl alcohol, and polyamide and first removing thorium from the solution. Various analytical methods were used to characterize the produced dicarboxylic acid/polyvinyl alcohol/polyamide poly‐adsorbent. The practical conditions on adsorption effectiveness evaluated to pH 3.5, 60 mg poly‐adsorbent, 60 min. Th(IV) uptake for poly‐adsorbent is 107.3 mg/g. The linear and nonlinear uptake for the pseudo‐second‐order is closer to the practical uptake (107.71 mg/g). Hence, the kinetic analysis verified the sorption mechanism. Also, the uptake of linear (107.64 mg/g) and nonlinear (108.63 mg/g) types for the Langmuir isotherm is closer to the practical uptake (107.71 mg/g); thus, the sorption isotherm was suitably utilizing Langmuir modeling. Thermodynamic studies proved that the sorption is spontaneous, exothermic, and random due to the negative ΔG°, negative ΔH°, and positive ΔS° during the thorium adsorption process on poly‐adsorbent. In addition, the regeneration ability of poly‐adsorbent was tested utilizing 1.5 M H2SO4. After six cycles, the poly‐adsorbent showed about 83 % regeneration efficacy. The results confirmed that the dicarboxylic acid/polyvinyl alcohol/polyamide poly‐adsorbent might be effective in removing Th(IV) from the watery solution. [ABSTRACT FROM AUTHOR]

This review underscores the potential of metal‐organic frameworks (MOFs), exemplified by MIL‐100(Fe), as catalysts in the conversion of 5‐Hydroxymethyl Furfural to 2,5‐Furan Dicarboxylic Acid, which is crucial in bioplastics and value‐added chemical production. MOFs exhibit advantages, including recyclability, stability, and catalytic potential under mild conditions. Despite promising results, MOFs in this application are underexplored compared to traditional metal catalysts. Noble metal catalysts (Au, Pt, and Pd) face challenges such as cost and limited recyclability. Mechanistic studies favor the DFF route, highlighting the oxidation of HMF's hydroxyl group as predominant. Molecular oxygen proves effective for HMF to FDCA transformation, with gold‐based catalysts noted for selectivity. Ongoing industrial efforts by companies like Avantium indicate a shift towards sustainable alternatives. This review highlights research gaps concerning the necessity for custom Metal‐Organic Framework (MOF) catalysts in the transformation of hydroxymethylfurfural (HMF) into 2,5‐furandicarboxylic acid (FDCA). The study recommends, among other things, 1) the adoption of base‐free conversion systems, 2) a focus on large‐scale FDCA manufacturing, prioritizing environmental sustainability despite prevailing cost challenges, and 3) fostering multidisciplinary collaboration. Utilizing advanced engineering software, such as ASPEN HYSYS, is proposed for optimizing these processes and paving the way for the successful industrialization of FDCA in the future. [ABSTRACT FROM AUTHOR]

Herein, we synthesized three new LMOFs, [Cd(TPPE)0.5(oba)(H2O)]n (LMOF-1), [Cd2(TPPE)(bpdc)2]n (LMOF-2), and [Cd2(TPPE)(sdc)2]n (LMOF-3) (TPPE = 1,1,2,2-tetra[4-(pyridin-4-yl)phenyl]ethylene, oba = 4,4′-diphenyl ether dicarboxylic acid, bpdc = 4,4′-biphenyl dicarboxylic acid, sdc = 4,4′-styrene dicarboxylic acid), with high quantum yields of 43.74%, 36.68% and 45.89%, respectively, exceeding those reported for most Cd-based LMOFs. All three LMOFs have good detection sensitivity for Fe3+, CrO42− and Cr2O72−. Surprisingly, Na+ can rarely but significantly enhance the fluorescence intensity of LMOF-3, and the detection limit is 1.90 × 10−5 M. This is the first reported LMOF material that can quantitatively analyze Na+ among references. All results indicate that the three MOFs can be developed into phosphor materials and fluorescent chemical sensors for detecting ions in water. [ABSTRACT FROM AUTHOR]

The current work aims to generate multifunctional MOFs by incorporating a well-known inorganic motif, a trinuclear Cu-pyrazolate [Cu3(μ3-OH)(μ-Pyz)3] (T-CuP) unit, as a node of the network. Accordingly, we report herein the synthesis and properties of five new compounds using five V-shaped dicarboxylic acids as auxiliary ligands. The structural features are consistent with the theme of grafting T-CuP units as nodal points of architectures whose chassis are primarily made of bent acids. V-shaped acids also induce a helical nature inside resulting frameworks. Beside their structural and physical features, T-CuP unit-based MOFs also vindicate our thematic approach of the trinuclear Cu-pyrazolate unit imparting specific physicochemical properties, such as magnetic, electrical, and catalytic properties, to resultant MOFs. The MOFs show excellent catalytic properties in reducing 4-nitrophenol, which could be attributed to the porous nature of the network along with the presence of metal centres with unsaturated coordination within the T-CuP unit. Furthermore, efficient photocatalytic degradation of harmful organic dyes confirms their importance for environmental remediation. The presence of a T-CuP unit and various functional groups also make some of the MOFs suitable candidates for electrical applications, which is indeed manifested in encouraging proton conductivity. Finally, the potential of current MOFs, fitted with a magnetically important trinuclear Cu-pyrazolate motif, as magnetic materials has also been thoroughly investigated. [ABSTRACT FROM AUTHOR]

Electrochemical catalysis emerges as a promising method for lignin depolymerization due to its environmental friendliness and mild reaction condition. Metal oxyhydroxides have displayed appealing electrochemical activity for the oxidation for various biomass substrates. In this study, we prepared different metal (Ni, Co, Mn, Fe, and Cu) oxyhydroxides on nickel foam electrodes through electrodeposition. Their electrochemical properties were characterized and the reactivity towards lignin oxidative cleavage was investigated using lignin model compounds. NiOOH exhibited significantly higher activity for oxidative cleavage of the β-O-4 linkage compared to other metal oxyhydroxides, resulting in a 93% yield of aromatic monomers with 99% selectivity towards benzoic acids. Furthermore, the reconstruction process of the active site NiOOH was revealed by in-situ testing, and the reaction mechanism was explored. The non-phenolic structure underwent Cβ–Cγ/Cβ–O or Cα–Cβ cleavage, predominantly producing benzoic acids, while the phenolic structure was rapidly oxidized into dicarboxylic acids over NiOOH. [ABSTRACT FROM AUTHOR]

Enhancing the production of biochemicals from lignocellulosic biomass is one potential way to decrease society's dependence on fossil fuels. Aromatic compounds obtained from plant biomass can be used as substrates for microbial production of dicarboxylic acids such as 2-pyrone-4,6-dicarboxylic acid (PDC) and cis,cis-muconic acid, which are building blocks for the manufacturing of polymer-based fibers and materials. In this study, we used an engineered strain of the bacterium Novosphingobium aromaticivorans to investigate how to increase PDC productivity in flow-through bioreactors receiving aqueous solutions of aromatics. At the best operational conditions tested, we achieved stable PDC production rates of 0.77 gPDC L−1 h−1 with p-hydroxybenzoic acid, 1.93 gPDC L−1 h−1 with syringic acid, and 1.53 gPDC L−1 h−1 with the products from alkaline pretreated poplar biomass. PDC titers in these reactors ranged from 7.7 to 15 g L−1 (42 to 80 mM) and were limited by aromatic solubility in the case of syringic acid, or by accumulation of protocatechuic acid from p-hydroxybenzoic acid when high aromatic loading rates were used. The use of high aromatic loading rates, hollow-fiber membranes to concentrate the microbial cells, and NH4OH for pH control were factors that contributed to this study achieving the highest PDC productivities reported to date. Overall, our findings demonstrate strategies that can be used to increase bioreactor productivity when aromatic substrates are delivered in aqueous form. These findings may also provide useful insight for production of other biochemicals from aromatic streams using N. aromaticivorans or other microbial chassis. [ABSTRACT FROM AUTHOR]

We report primordial aqueous alteration signatures in water-soluble organic molecules from the carbonaceous asteroid (162173) Ryugu by the Hayabusa2 spacecraft of JAXA. Newly identified low-molecular-weight hydroxy acids (HO-R-COOH) and dicarboxylic acids (HOOC-R-COOH), such as glycolic acid, lactic acid, glyceric acid, oxalic acid, and succinic acid, are predominant in samples from the two touchdown locations at Ryugu. The quantitative and qualitative profiles for the hydrophilic molecules between the two sampling locations shows similar trends within the order of ppb (parts per billion) to ppm (parts per million). A wide variety of structural isomers, including α- and β-hydroxy acids, are observed among the hydrophilic molecules. We also identify pyruvic acid and dihydroxy and tricarboxylic acids, which are biochemically important intermediates relevant to molecular evolution, such as the primordial TCA (tricarboxylic acid) cycle. Here, we find evidence that the asteroid Ryugu samples underwent substantial aqueous alteration, as revealed by the presence of malonic acid during keto–enol tautomerism in the dicarboxylic acid profile. The comprehensive data suggest the presence of a series for water-soluble organic molecules in the regolith of Ryugu and evidence of signatures in coevolutionary aqueous alteration between water and organics in this carbonaceous asteroid. In this study, the authors report primordial aqueous alteration signatures in water-soluble organic molecules from the carbonaceous asteroid Ryugu. This provides evidence o coevolutionary aqueous alteration between water and organics in this asteroid. [ABSTRACT FROM AUTHOR]

Constructing self‐repairing epoxy materials based on transesterification chemistry can be regarded as a potential path for practical industrial applications given on its simplicity and ease of processing. However, there is still a challenge to improve the slow bonding exchange process for desired healing performances. Herein, this work reports a simple and effective strategy to prepare high‐biomass‐content self‐repairing epoxy materials by introducing polyester oligomer (PEO) dicarboxylic acid as modifier into epoxidized soybean oil and itaconic acid compounds. The PEO is synthesized from glutaric anhydride and 1,4‐cyclohexanediol, as well possess a unique pentamer molecular structure. It not only endows the epoxy system with improved molecular mobility in virtue of its long‐chain structure, but also increases the number the essential ester groups of transesterification process, thus synergistically promoting bonding exchange rate for expected properties. As a result, the employment of PEO decreases the activation energy from 100 to 70 KJ/mol, as well as presents optimized self‐repairing efficiency in storage modulus and tensile strength tests compared to the control group. It may provide a new and practical way to fabricate high‐effective self‐repairing epoxy system for industrial applications. [ABSTRACT FROM AUTHOR]

Background: An important step in replacing petrochemical products with sustainable, cost-effective alternatives is the use of feedstocks other than, e.g., pure glucose in the fermentative production of platform chemicals. Ustilaginaceae offer the advantages of a wide substrate spectrum and naturally produce a versatile range of value-added compounds under nitrogen limitation. A promising candidate is the dicarboxylic acid malic acid, which may be applied as an acidulant in the food industry, a chelating agent in pharmaceuticals, or in biobased polymer production. However, fermentable residue streams from the food and agricultural industry with high nitrogen content, e.g., sugar beet molasses, are unsuited for processes with Ustilaginaceae, as they result in low product yields due to high biomass and low product formation. Results: This study uncovers challenges in evaluating complex feedstock applicability for microbial production processes, highlighting the role of secondary substrate limitations, internal storage molecules, and incomplete assimilation of these substrates. A microliter-scale screening method with online monitoring of microbial respiration was developed using malic acid production with Ustilago trichophora on molasses as an application example. Investigation into nitrogen, phosphate, sulphate, and magnesium limitations on a defined minimal medium demonstrated successful malic acid production under nitrogen and phosphate limitation. Furthermore, a reduction of nitrogen and phosphate in the elemental composition of U. trichophora was revealed under the respective secondary substrate limitation. These adaptive changes in combination with the intricate metabolic response hinder mathematical prediction of product formation and make the presented screening methodology for complex feedstocks imperative. In the next step, the screening was transferred to a molasses-based complex medium. It was determined that the organism assimilated only 25% and 50% of the elemental nitrogen and phosphorus present in molasses, respectively. Due to the overall low content of bioavailable phosphorus in molasses, the replacement of the state-of-the-art nitrogen limitation was shown to increase malic acid production by 65%. Conclusion: The identification of phosphate as a superior secondary substrate limitation for enhanced malic acid production opens up new opportunities for the effective utilization of molasses as a more sustainable and cost-effective substrate than, e.g., pure glucose for biobased platform chemical production. [ABSTRACT FROM AUTHOR]

The present paper is devoted to the oxidation reaction of a series of cyclic ketones such as cyclopentanone, cyclohexanone, cycloheptanone and cyclooctanone by 3,5-dimethyl pyrazolium chlorochromate in 50% of aqueous acetic acid medium at 308 K. The reaction is first-order in the concentration of oxidant, substrate, and H+. The reaction rate accelerates as the dielectric constant of the reaction medium decreases. An increase in ionic strength does not affect the rate constant. The oxidation process has not changed with the effect of acrylonitrile, and the reaction with manganese sulfate hinders the oxidation rate. Five distinct temperatures were explored to determine the thermodynamic and activation parameters. Dicarboxylic acid is generated as a resulting product of oxidation. From these chemical kinetic studies, a reasonable mechanism and rate expression could be proposed. The reactivity order has been rationalised. [ABSTRACT FROM AUTHOR]

The 1,3-dipolar cycloaddition reaction of substituted dinitroacetonitriles with isoquinoline in the presence of acetylene dicarboxylic acid dimethyl ester results in the formation of a mixture of diastereomeric dimethyl 2-dinitromethyl-1,1bH-pyrimido[2,1-a]isoquinoline-3,4-dicarboxylates. The obtained compounds can be considered as promising synthons with potential antituberculosis and fungicidal activity. [ABSTRACT FROM AUTHOR]

Since the seminal work presented by Olah in 1966 on fluorinated carbocations, several strategies have been presented to introduce fluorinated moieties in polymer backbones via carbocation chemistry. The hexafluoroisopropylidene (6F) group is well known for its ability to enhance thermal properties and processability of polymers. However, its direct electrophilic incorporation into polymers has been largely ignored due to the challenges posed by activating hexafluoroacetone monomer for electrophilic aromatic substitution (EAS). In this article, we review the role of fluorinated carbocations from 1966 up to our recent versatile fluoroalkylation strategy to directly enchain the 6F group in polymers. Via EAS interfacial polymerization we reacted hexafluoroacetone trihydrate (HFAH) with aromatic monomers in triflic anhydride (Tf2O) and 1,2-dichloroethane (DCE) with Aliquat® 336. In addition, the polymerization of dibenzo-1,4-dioxin with HFAH is presented. A semi-fluorinated diol, 4,4′-bis(2-hydroxyhexafluoroisopropyl)diphenyl ether, was synthesized by this method and used to prepare the first reported polycarbonate with hexafluoroisopropoxy groups –C(CF3)2O– incorporated in the main chain via polycondensation. Polysilyl ethers were also prepared from this diol. Additionally, we briefly mention Carraher's legacy in the synthesis of metal-containing polymers via reactions of group IVB metallocene dichloride with dinucleophiles (diamines, diol, dicarboxylic acids, and dithiols) in solution and interfacial conditions in terms of electrophilic vs nucleophilic polycondensation. The new acidic, sterically hindered semi-fluorinated diol and bisphenol AF were reacted with group IVB metallocene dichloride in attempts to form metallocene condensation polymers with improved solubility. [ABSTRACT FROM AUTHOR]

• RPLC-ESI-MS/MS of medium-chain dicarboxylic fatty acids (DFAs) in siccative oils. • XRF, µRaman, and FORS spectroscopies to identify the inorganic pigments. • Analysis of paint replicas of linseed oil mixed with chrome yellow and cadmium red. • Semi-quantitative data on C 8 , C 9 , C 10 , C 11 DFA. • Recognition of DFA from real old paintings. To tackle the ageing phenomena of precious artworks, the binding media have been increasingly explored in cultural heritage. When siccative oils are employed as paint media, medium-chain dicarboxylic fatty acids (DFAs), also known as dioic acids, are generated from unsaturated fatty acyl chains by hydroxyl and hydroperoxyl radicals during the drying process. Hitherto, gas-chromatography coupled with mass spectrometry (MS) has represented the foremost technique for the investigation of DFAs upon proper derivatization reactions, yet the current work aims to introduce an alternative approach based on reversed-phase liquid chromatography, negative-ion-mode electrospray ionization with high-resolution/accuracy MS and tandem MS. Painting reconstructions of linseed oil mixed with common inorganic pigments such as chrome yellow and cadmium red were investigated for their content of suberic (C 8), azelaic (C 9), sebacic (C 10), and undecanedioic (C 11) acids. For the identification of these DFAs as unbounded species, retention time data followed by confirmation of their accurate m/z measurements and a detailed analysis of their fragmentation patterns via tandem MS were used. To estimate the quantity of DFAs, samples were spiked with a suitable internal standard before lipid extraction. This analytical strategy was successfully applied to three 50-year-old oil paintings, using samples of only a few milligrams (i.e. , 25–50 mg). Notably, a difference in DFA profiles was observed within the artwork, with yellow pigments exhibiting relatively lower content compared to red ones. Spectroscopic techniques revealed alterations relevant to the chemical composition of these pigments during the ageing process. Likely the chromate ion, a component of chrome yellow pigment, undergoes oxidation which may hinder the generation of hydroxyl and hydroperoxyl radicals by the Fenton reaction, as the iron catalyst naturally occurring in the drying oil is potentially affected. [ABSTRACT FROM AUTHOR]

Introduction: Tonsillectomies are among the most common surgical procedures in children, with over 500 000 cases annually in the United States. Despite universal administration of intraoperative opioid analgesia, three out of five children undergoing tonsillectomy report moderate‐to‐severe pain upon recovering from anesthesia. The underlying molecular mechanisms of post‐tonsillectomy pain are not well understood, limiting the development of targeted treatment strategies. Our study aimed to identify candidate serum metabolites associated with varying severity of post‐tonsillectomy pain. Methods: Venous blood samples and pain scores were obtained from 34 children undergoing tonsillectomy ± adenoidectomy, and metabolomic analysis was performed. Supervised orthogonal projections to latent structures discriminant analysis were employed to identify differentially expressed metabolites between children with severe and mild pain, as well as between moderate and mild pain. Results: Pain scores differentiated children as mild (n = 6), moderate (n = 14), or severe (n = 14). Four metabolites (fatty acid 18:0(OH), thyroxine, phosphatidylcholine 38:5, and branched fatty acids C27H54O3) were identified as candidate biomarkers that differentiated severe vs. mild post‐tonsillectomy pain, the combination of which yielded an AUC of 0.91. Similarly, four metabolites (sebacic acid, dicarboxylic acids C18H34O4, hydroxy fatty acids C18H34O3, and myristoleic acid) were identified as candidate biomarkers that differentiated moderate vs. mild post‐tonsillectomy pain, with AUC values ranging from 0.85 to 0.95. Conclusion: This study identified novel candidate biomarker panels that effectively differentiated varying severity of post‐tonsillectomy pain. Further research is needed to validate these data and to explore their clinical implications for personalized pain management in children undergoing painful surgeries. [ABSTRACT FROM AUTHOR]

The presence of organics in Bayer liquors has a notable adverse effect on alumina production. Among these organics, dicarboxylic acids are a class of low molecular weight compounds that have yet to be studied for their decomposition in Bayer liquors using advanced oxidation techniques. This study aims to investigate the oxidation behavior of four dicarboxylic acids, including malonic acid (C3), succinic acid (C4), glutaric acid (C5), and adipic acid (C6), in Bayer liquors. The influences of different variables, such as sodium persulfate (SPS) dosage, initial organic concentration, caustic soda concentration, reaction temperature, and reaction time, on the advanced oxidation process of dicarboxylic acids were also studied. The results of the experiment indicate that an increase in SPS dosage, initial organic concentration, reaction temperature, and reaction time promoted the removal of total organic carbon (TOC). However, the concentration of caustic soda had an inhibitory effect on TOC removal, and it also affected the type of decomposition products of dicarboxylic acids. The EPR results revealed that the reactive groups responsible for organic decomposition were SO 4 - · and HO · . Dicarboxylic acids were found to produce several decomposition products, including carbon dioxide (in the form of carbonate), formic acid, and oxalic acid. Additionally, malonic and fumaric acids were observed as the main oxidation intermediates for dicarboxylic acids with C-atom numbers > 3. A reaction mechanism for succinic acid was also proposed. Advanced oxidation techniques have shown promise as a means of removing organics from Bayer liquors. [ABSTRACT FROM AUTHOR]

Background: Ideally, the barrier properties of a fruit's cuticle persist throughout its development. This presents a challenge for strawberry fruit, with their rapid development and thin cuticles. The objective was to establish the developmental time course of cuticle deposition in strawberry fruit. Results: Fruit mass and surface area increase rapidly, with peak growth rate coinciding with the onset of ripening. On a whole-fruit basis, the masses of cutin and wax increase but on a unit surface-area basis, they decrease. The decrease is associated with marked increases in elastic strain. The expressions of cuticle-associated genes involved in transcriptional regulation (FaSHN1, FaSHN2, FaSHN3), synthesis of cutin (FaLACS2, FaGPAT3) and wax (FaCER1, FaKCS10, FaKCR1), and those involved in transport of cutin monomers and wax constituents (FaABCG11, FaABCG32) decreased until maturity. The only exceptions were FaLACS6 and FaGPAT6 that are presumably involved in cutin synthesis, and FaCER1 involved in wax synthesis. This result was consistent across five strawberry cultivars. Strawberry cutin consists mainly of C16 and C18 monomers, plus minor amounts of C19, C20, C22 and C24 monomers, ω-hydroxy acids, dihydroxy acids, epoxy acids, primary alcohols, carboxylic acids and dicarboxylic acids. The most abundant monomer is 10,16-dihydroxyhexadecanoic acid. Waxes comprise mainly long-chain fatty acids C29 to C46, with smaller amounts of C16 to C28. Wax constituents are carboxylic acids, primary alcohols, alkanes, aldehydes, sterols and esters. Conclusion: The downregulation of cuticle deposition during development accounts for the marked cuticular strain, for the associated microcracking, and for their high susceptibility to the disorders of water soaking and cracking. [ABSTRACT FROM AUTHOR]

Dicarboxylic fatty acids are generated in the liver and kidney in a minor pathway called fatty acid ω-oxidation. The effects of consuming dicarboxylic fatty acids as an alternative source of dietary fat have not been explored. Here, we fed dodecanedioic acid, a 12-carbon dicarboxylic (DC12), to mice at 20% of daily caloric intake for 9 weeks. DC12 increased metabolic rate, reduced body fat, reduced liver fat, and improved glucose tolerance. We observed DC12-specific breakdown products in liver, kidney, muscle, heart, and brain, indicating that oral DC12 escaped first-pass liver metabolism and was utilized by many tissues. In tissues expressing the “a” isoform of acyl-CoA oxidase-1 (ACOX1), a key peroxisomal fatty acid oxidation enzyme, DC12 was chain shortened to the TCA cycle intermediate succinyl-CoA. In tissues with low peroxisomal fatty acid oxidation capacity, DC12 was oxidized by mitochondria. In vitro, DC12 was catabolized even by adipose tissue and was not stored intracellularly. We conclude that DC12 and other dicarboxylic acids may be useful for combatting obesity and for treating metabolic disorders. [ABSTRACT FROM AUTHOR]

2,6-pyridine dicarboxylic acid (DPA) is an exceptional biomarker of notorious anthrax spores. Therefore, the rapid, sensitive, and selective quantitative detection of DPA is extremely significant and urgent. This paper reports a Zn(II) metal–organic framework with the formula of {[Zn6(NDA)6(DPBT)3] 2H2O·3DMF}n (MOF-1), which consists of 2,6-naphthalenedicarboxylic acid (2,6-NDA), 4,7-di(4-pyridyl)-2,1,3-benzothiadiazole (DPBT), and Zn(II) ions. Structural analysis indicated that MOF-1 is a three-dimensional (3D) network which crystallized in the monoclinic system with the C2/c space group, revealing high pH, solvent, and thermal stability. Luminescence sensing studies demonstrated that MOF-1 had the potential to be a highly selective, sensitive, and recyclable fluorescence sensor for the identification of DPA. Furthermore, fluorescent test paper was made to detect DPA promptly with color changes. The enhancement mechanism was established by the hydrogen-bonding interaction and photoinduced electron transfer transition between MOF-1 and DPA molecules. [ABSTRACT FROM AUTHOR]

Two new triarylamine-based diamine monomers, namely, N,N′-bis(4-methoxyphenyl)-N,N′-bis(4-(4-aminophenyl-4′-methoxyphenylamino)phenyl)-p-phenylenediamine (3) and N,N′-bis(4-methoxyphenyl)-N,N′-bis(4-((4-aminophenyl-1-naphthyl)amino)phenyl)-p-phenylenediamine (7), were successfully synthesized and led to two series of electroactive polyamides by polycondensation reactions with common aromatic dicarboxylic acids. The polymers demonstrated multicolored electrochromism, high optical contrast, and remarkable enhancements in redox and electrochromic stability. Compared to other triarylamine-based polymers, the studied polyamides exhibited enhanced electrochromic stability (only 3~6% decay of its coloration efficiency at 445 nm after 14,000 switching cycles) at the first oxidation stage. The polyamides also showed strong absorption in the near-infrared region upon oxidation. Polymers with multicolored electrochromism and high redox stability can be developed by incorporation of four triarylamine cores in each repeat unit and electron-donating methoxy groups on the active sites of the triphenylamine units. [ABSTRACT FROM AUTHOR]

Electroreductive ring-opening carboxylation of styrene carbonates with CO2 to achieve dicarboxylic acids and/or β-hydroxy acids has been developed via the selective cleavage of the C(sp³)-O bond in cyclic carbonates. The product selectivity is probably determined by the stability and reactivity of the key benzylic radical and carbanion intermediate. [ABSTRACT FROM AUTHOR]

Chemical upcycling of plastics provides an important direction for solving the challenging issues of plastic pollution and mitigating the wastage of carbon resources. Among them, catalytic oxidative cracking of plastics to produce high–value chemicals, such as catalytic oxidation of polyethylene (PE) to produce fatty dicarboxylic acids, catalytic oxidation of polystyrene (PS) to produce benzoic acid, and catalytic oxidation of polyethylene terephthalate (PET) to produce terephthalic acid under mild conditions has attracted increasing attention, and some exciting progress has been made recently. In this article, we will review recent progresses on the catalytic oxidation upcycling of plastics and provide our understanding on the current challenges in catalytic oxidation upcycling of plastics. [ABSTRACT FROM AUTHOR]

Saline-sodic stress induces iron deficiency in rice, reduces leaf photosynthetic performance, and inhibits yield enhancement. In this study, we investigated the effects of exogenous Fe on the photosynthetic performance and transcriptomics of two different tolerant rice cultivars CB9 (Changbai9: saline tolerant cultivar) and TH899 (Tonghe899: saline sensitive cultivar) with 4-week-old Fe-deficient rice seedlings under saline stress, Fe deficiency stress, and both co-stresses. The results showed that under saline and alkaline stress, spraying exogenous iron favored the growth of the two cultivars of rice, with a 32.68% and 39.82 increase in fresh weight, a 2.20-fold and 2.16-fold increase in pigment, respectively, and an 80.28% and 100.00% increase in net photosynthetic rate, respectively, as compared with the iron-deficiency treatment. Transcriptome analysis showed that we found a higher number of differentially expressed genes (7785 differentially expressed genes) in response to exogenous Fe spraying in the soda-salt sensitive variety TH899. The differentially expressed genes that are common to the two cultivars are primarily enriched in metabolic pathways, including plant hormone signal transduction (map04075) and phenylpropanoid biosynthesis (map00940). Specifically, among these genes, 14 are differentially expressed in the carotenoid biosynthetic metabolic pathway. The differentially expressed genes specific to the salinity-tolerant variety CB9 were mainly enriched in the metabolic pathways of glyoxylate and dicarboxylic acid methyl metabolism (map00630), and carbon fixation in photosynthetic organisms (map00710), among which 20 genes were significantly expressed in the pathway for carbon fixation in photosynthetic organisms (map00710). The research results offer specific theoretical support for enhancing the salt tolerance of rice. [ABSTRACT FROM AUTHOR]

Legumes house nitrogen-fixing endosymbiotic rhizobia in specialised polyploid cells within root nodules. This results in a mutualistic relationship whereby the plant host receives fixed nitrogen from the bacteria in exchange for dicarboxylic acids. This plantmicrobe interaction requires the regulation of multiple metabolic and physiological processes in both the host and symbiont in order to achieve highly efficient symbiosis. Recent studies have showed that the success of symbiosis is influenced by the circadian clock of the plant host. Medicago and soybean plants with altered clock mechanisms showed compromised nodulation and reduced plant growth. Furthermore, transcriptomic analyses revealed that multiple genes with key roles in recruitment of rhizobia to plant roots, infection and nodule development were under circadian control, suggesting that appropriate timing of expression of these genes may be important for nodulation. There is also evidence for rhythmic gene expression of key nitrogen fixation genes in the rhizobium symbiont, and temporal coordination between nitrogen fixation in the bacterial symbiont and nitrogen assimilation in the plant host may be important for successful symbiosis. Understanding of how circadian regulation impacts on nodule establishment and function will identify key plant-rhizobial connections and regulators that could be targeted to increase the efficiency of this relationship. [ABSTRACT FROM AUTHOR]

Dendrimers are potent nanocarriers in drug delivery systems because their structure can be precisely controlled. We previously reported that polyamidoamine (PAMAM) dendrimers that were modified with 1,2-cyclohexanedicarboxylic acid (CHex) and phenylalanine (Phe), PAMAM-CHex-Phe, exhibited an effective association with various immune cells, including T-cells. In this study, we synthesized various carboxy-terminal Phe-modified dendrimers with different linkers using phthalic acid and linear dicarboxylic acids to determine the association of these dendrimers with Jurkat cells, a T-cell model. PAMAM-n-hexyl-Phe demonstrated the highest association with Jurkat T-cells. In addition, dendri-graft polylysine (DGL) with CHex and Phe, DGL-CHex-Phe, was synthesized, and its association with Jurkat cells was investigated. The association of DGL-CHex-Phe with T-cells was higher than that of PAMAM-CHex-Phe. However, it was insoluble in water and thus it is unsuitable as a drug carrier. Model drugs, such as protoporphyrin IX and paclitaxel, were loaded onto these dendrimers, and the most model drug molecules could be loaded into PAMAM-CHex-Phe. PTX-loaded PAMAM-CHex-Phe exhibited cytotoxicity against Jurkat cells at a similar level to free PTX. These results suggest that PAMAM-CHex-Phe exhibited both efficient T-cell association and drug loading properties. [ABSTRACT FROM AUTHOR]

Pyrrole‐2,5‐dicarboxylic acid (PDCA) is a heterocyclic aromatic dicarboxylic acid that may emerge as a new monomer for polyester production. Compared to its structurally related and bio‐based furan‐2,5‐dicarboxylic acid (FDCA) that is already used for the production of polyethylene furanoate (PEF), PDCA shows excellent potential as its nitrogen can be targeted for further derivatization, thus enabling tuning of the properties of a PDCA containing polymer. In light of this, we recognized the need to explore efficient synthetic approaches for producing PDCAs in high yields. Here, we report a five‐step synthesis route for N‐substituted PDCAs starting from pyrrole, with total yields up to 42 %. The synthetic approach allowed the introduction of several different functional moieties to the pyrrole nitrogen, such as aliphatic saturated and unsaturated side‐chains, as well as benzylic groups. [ABSTRACT FROM AUTHOR]

Solid electrolyte materials with high structural stability and excellent proton conductivity (σ) have long been a popular and challenging research topic in the fuel cell field. This problem can be addressed because of the crystalline metal–organic frameworks' (MOFs') high structural stability, adjustable framework composition, and dense H-bonded networks. Herein, one highly stable Sr(II) MOF, {[Sr(H2tmidc)2(H2O)3]·4H2O}n (1) (H3tmidc = 2-(1H-tetrazolium-1-methylene)-1H-imidazole-4,5-dicarboxylic acid) was successfully fabricated, which was structurally characterized by single-crystal X-ray diffraction and electrochemically examined by the AC impedance determination. The results demonstrated that the σ of the compound manifested a positive dependence on temperature and humidity, and the optimal proton conductivity is as high as 1.22 × 10−2 S/cm under 100 °C and 98% relative humidity, which is at the forefront of reported MOFs with ultrahigh σ. The analysis of the proton conduction mechanism reveals that numerous tetrazolium groups, carboxyl groups, coordination, and crystallization water molecules in the framework are responsible for the high efficiency of proton transport. This work offers a fresh perspective on how to create novel crystalline proton conductive materials. [ABSTRACT FROM AUTHOR]

Sorption of dicarboxylic acid molecules of pharmaceutical interest such as azelaic acid (AzA), in syndiotactic polystyrene (sPS) films presenting δ and ε nanoporous crystalline structure, is reported. Fourier Transform Infrared (FTIR), Polarized FTIR and Wide‐Angle X‐ray diffraction (WAXD) patterns on axially oriented sPS films has been performed to verify their sorption in crystalline lattices resulting in the formation of co‐crystalline (CC) phases. Experimental evidence provides that AzA molecules can be included in the crystalline nanochannels of ε phase both as isolated and hydrogen‐bonded molecules whereas they are only dissolved in the amorphous phase of δ samples. [ABSTRACT FROM AUTHOR]

A new ZnII coordination polymer (CP) based on 2,3‐pyrazine dicarboxylic acid (H2pzdc) and 4,4′‐bipyridine (bpy) (ZCP) was synthesized using a facile slow evaporation method. Single‐crystal X‐ray diffraction revealed that ZCP is a two‐dimensional porous CP, [Zn2(pzdc)2(bpy)(H2O)2]n, with van der Waals forces as the dominant interaction within its layers forming a 63 network. Employing energetic ultrasound irradiation, nanoscale ZCP (nZCP) was successfully synthesized and Eu3+ ions were incorporated within its host lattice (Eu@nZCP). The resulting platform exhibits superior fluorescence characteristics and demonstrates notable optical durability. Therefore, it was used as a dual detection fluorescent sensing platform for the detection of mercury and l‐cysteine (l‐Cys) in aqueous media through a turn‐off/on strategy. In the turn‐off process, the fluorescence emission of Eu@nZCP progressively quenches by the addition of HgIIvia a photo‐induced electron transfer (PET) mechanism. The fluorescence of Eu@nZCP is quenched to establish a low fluorescence background through the incorporation of HgII. This devised turn‐on fluorescent system is suitable for the recognition of l‐Cys (based on the strong affinity of l‐Cys to the HgII ion) through a quencher detachment mechanism. This method attained a relatively wide linear range, spanning from 0.001 to 25 µM, with the low detection limit of 5 nM for the sensing of HgII. Also, the corresponding limit of detection (LOD) for l‐Cys is 8 nM in a relatively wide linear range, spanning from 0.001 to 40 µM. [ABSTRACT FROM AUTHOR]

Octacalcium phosphate (OCP) is an attractive base material to combine into components developed for medical purposes, especially those used in bone replacement procedures, not only because of its excellent biocompatibility but also because of its ability to intercalate with multiple types of molecular layers such as silica, dicarboxylic acid, and various cations. On the other hand, there are no examples of simultaneous substituting for several different compounds on OCPs. Therefore, in this study, the physical and mechanical strength (DTS: diametral tensile strength) of OCPs substituted with both silica and dicarboxylic acids (thiomalate: SH-malate) were evaluated. By optimizing the amount of SH-malate, we were able to prepare a block consisting of OCPs with both silica and SH-malate supported in the interlayer. The composition of the OCP-based compound comprising this block was Ca8Na1.07H6.33(PO4)4.44(SiO4)1.32(SH-malate)2.40·nH2O. Interestingly, the low mechanical strength, a drawback of silica-substituted OCP blocks, could be improved by dicarboxylic acid substituting. The dicarboxylic acid addition increased the mechanical strength of silica-substituted OCP blocks, and the acid successfully incorporated into the interlayer, even with the presence of silica. These results are expected to advance the creation of better silica-substituted OCPs and improved bone replacement materials. [ABSTRACT FROM AUTHOR]

Novel electrode and electrolyte materials are crucial for enhancing supercapacitor efficiency. Metal–organic frameworks (MOFs) have gained attention owing to their high porosity and surface area. However, their low capacity limits their usage. To tackle this, a highly effective mechanochemical annealing strategy is implemented to improve their efficiency. Three different forms of metal oxides NiCo2O4 are derived from bimetallic MOFs by incorporating Ni2+ and Co2+ with linkers 1,3,5‐benzene tricarboxylic acid (MO‐1), 2,6‐naphthalene dicarboxylic acid (MO‐2), and 1,2,4,5‐benzene tetracarboxylic acid (MO‐3). The synthesized metal oxides have different morphologies due to different linkers and displayed remarkable electrochemical performance, attributed to favorable charge transport paths and enhanced electrochemical double‐layer capacitance with an enlarged specific surface area. These metal oxides exhibit specific capacitance values of 913.3, 43.4, and 210 F g−1 at operating voltages of 0.55, 0.55, and 0.6 V for MO‐1, MO‐2, and MO‐3, respectively. Notably, MO‐1 shows extended discharging time and demonstrates the characteristic behavior of battery‐type supercapacitors, making it versatile. The fabricated hybrid supercapacitor (bimetal hybrid supercapacitor) shows pseudocapacitive behavior, reaching up to 1.5 V with a specific capacitance of 65.6 F g−1, energy density of 73.83 W h kg−1, and power density of 1181.2 W kg−1. [ABSTRACT FROM AUTHOR]

An intramolecular electrochemical dehydration reaction of dicarboxylic acids to their cyclic anhydrides is presented. This electrolysis allows dicarboxylic acids as naturally abundant, inexpensive, safe, and readily available starting materials to be transformed into carboxylic anhydrides under mild reaction conditions. No conventional dehydration reagent is required. The obtained cyclic anhydrides are highly valuable reagents in organic synthesis, and in this report, we use them in‐situ for acylation reactions of amines to synthesize amides. This work is part of the recent progress in electrochemical dehydration, which – in contrast to electrochemical dehydrogenative reactions for example – is an underexplored field of research. The reaction mechanism was investigated by 18O isotope labeling, revealing the formation of sulfate by electrochemical oxidation and hydrolysis of the thiocyanate‐supporting electrolyte. This transformation is not a classical Kolbe electrolysis, because it is non‐decarboxylative, and all carbon atoms of the carboxylic acid starting material are contained in the carboxylic anhydride. In total, 20 examples are shown with NMR yields up to 71 %. [ABSTRACT FROM AUTHOR]

Background: Dodecanedioic acid (DDA), a typical medium-chain dicarboxylic fatty acid with widespread applications, has a great synthetic value and a huge industrial market demand. Currently, a sustainable, eco-friendly and efficient process is desired for dodecanedioic acid production. Results: Herein, a multi-enzymatic cascade was designed and constructed for the production of DDA from linoleic acid based on the lipoxygenase pathway in plants. The cascade is composed of lipoxygenase, hydroperoxide lyase, aldehyde dehydrogenase, and unidentified double-bond reductase in E. coli for the main cascade reactions, as well as NADH oxidase for cofactor recycling. The four component enzymes involved in the cascade were co-expressed in E. coli, together with the endogenous double-bond reductase of E. coli. After optimizing the reaction conditions of the rate-limiting step, 43.8 g L− 1 d− 1 of DDA was obtained by a whole-cell one-pot process starting from renewable linoleic acid. Conclusions: Through engineering of the reaction system and co-expressing the component enzymes, a sustainable and eco-friendly DDA biosynthesis route was set up in E. coli, which afforded the highest space time yield for DDA production among the current artificial multi-enzymatic routes derived from the LOX-pathway, and the productivity achieved here ranks the second highest among the current research progress in DDA biosynthesis. [ABSTRACT FROM AUTHOR]

The global plasticizer market is projected to increase from $17 billion in 2022 to $22.5 billion in 2027. Various emerging/alternative plasticizers entered the market following the ban on several phthalate plasticizers because of their harmful effects. However, there are limited data (especially peer-reviewed) on emerging plasticizers' toxicity and environmental impact. This review compiles available data on toxicity, exposure, environmental effects, and safe production of emerging plasticizers. It identifies gaps in scientific research and provides evidence that emerging plasticizers are potential cases of regrettable substitution. Several alternative plasticizers, such as acetyl tributyl citrate (ATBC), diisononyl cyclohexane-1,2 dicarboxylate (DINCH), tris-2-ethylhexyl phosphate (TEHP), tricresyl phosphate (TCP), tris-2-ethylhexyl phosphate (TPHP), bis-2-ethylhexyl terephthalate (DEHT), and tris-2-ethylhexyl trimellitate (TOTM), show potential endocrine-disrupting properties and other toxic characteristics. Some chemicals like bis-2-ethylhexyl adipate (DEHA), diisobutyl adipate (DIBA), ATBC, DINCH, bis-2-ethylhexyl sebacate (DOS), diethylene glycol dibenzoate (DEGDB), DEHT, and phosphate esters showed the potential to cause toxicity in aquatic species. Plus, there is great lack of information on compounds like diisononyl adipate (DINA), dibutyl adipate (DBA), diisodecyl adipate (DIDA), dipropylene glycol dibenzoate (DPGDB), dibutyl sebacate (DBS), alkylsulfonic phenyl ester (ASE), trimethyl pentanyl diisobutyrate (TXIB), DEGDB and bis-2-ethylhexyl sebacate (DOS). Some compounds like epoxidized soybean oil (ESBO), castor-oil-mono-hydrogenated acetate (COMGHA), and glycerin triacetate (GTA) are potentially safer or less toxic. Alternative plasticizers such as adipates (log Kow 4.3–10.1), cyclohexane dicarboxylic acids (log Kow 10), phosphate esters (log Kow 2.7–9.5), sebacates (log Kow 6.3–10.1), terephthalates (log Kow 8.4), and vegetable oil derivatives (log Kow 6.4–14.8) have log Kow values that are comparable to phthalate plasticizers (log Kow 7.5–10.4), indicating potential bioaccumulation and health consequences. Field studies have demonstrated that phosphate esters can undergo bioaccumulation and biomagnification, but there is a lack of bioaccumulation studies for other compounds. We also discuss the metabolism of emerging plasticizers, though data are limited. Our article highlights that numerous alternative compounds display potential health and ecological risks, indicating they might not be suitable substitutes for legacy plasticizers. There is also a lack of scientific data on most emerging plasticizers. This way, we call for increased research and timely regulatory action to prevent global contamination and health risks. Finally, this study presents a scientifically robust protocol to avoid harmful substitutions and ensure the production of safer chemicals. [ABSTRACT FROM AUTHOR]

Background: Recent studies have identified plasma metabolites associated with cognitive decline and Alzheimer's disease; however, little research on this topic has been conducted in Latinos, especially Puerto Ricans. Objective: This study aims to add to the growing body of metabolomics research in Latinos to better understand and improve the health of this population. Methods: We assessed the association between plasma metabolites and global cognition over 12 years of follow-up in 736 participants of the Boston Puerto Rican Health Study (BPRHS). Metabolites were measured with untargeted metabolomic profiling (Metabolon, Inc) at baseline. We used covariable adjusted linear mixed models (LMM) with a metabolite * time interaction term to identify metabolites (of 621 measured) associated with ∼12 years cognitive trajectory. Results: We observed strong inverse associations between medium-chain fatty acids, caproic acid, and the dicarboxylic acids, azelaic and sebacic acid, and global cognition. N-formylphenylalanine, a tyrosine pathway metabolite, was associated with improvement in cognitive trajectory. Conclusions: The metabolites identified in this study are generally consistent with prior literature and highlight a role medium chain fatty acid and tyrosine metabolism in cognitive decline. [ABSTRACT FROM AUTHOR]

Biomass burning serves as important sources of volatile organic compounds (VOCs), yet our understanding of the molecular characteristics of oxygenated volatile organic compounds (OVOCs) from fresh emissions remains limited. In this study, gaseous organic compounds in fresh smokes from burning typical Chinese crop straws and woods are measured using an iodide time‐of‐flight chemical ionization mass spectrometer. Approximately 750 molecular formulas are identified, with CHO compounds containing carbon, hydrogen and oxygen atoms accounting for 77%–95% of the total. C1–C3 organic acids and dicarboxylic acids dominate the total CHO signal intensities by 27%–48%, while well‐known molecular markers of biomass burning, such as monosaccharide, guaiacol and syringol derivatives, contribute 7%–17%. Notably, crop straw and wood burning emit a higher abundance of guaiacol than syringol derivatives by a factor of 5. Additionally, a variety of nitrogen‐containing compounds (mainly in the CHON group) is identified, including isocyanate, amide, amino acids, and pyridine. The mass spectral profiles of organic compounds are largely similar between crop straw and wood burning fuels, although wood burning produces higher contributions of compounds with carbon atoms numbers >10. The saturation concentrations of organic compounds are estimated using molecular formula‐based volatility parameterization, revealing that semi‐volatile and intermediate VOCs (S/intermediate volatility organic compounds (IVOCs)) predominate smoke releases by 35%–60% and 20%–43%, respectively, with only a small fraction of low‐volatility compounds. Given the widespread nature of biomass burning in winter China, our results may have significant implications for interpreting secondary organic aerosol formation through gas‐particle partitioning or aqueous‐phase reactions. Plain Language Summary: Biomass burning is a significant source of volatile organic compounds (VOCs), with oxygenated volatile organic compounds (OVOCs) being particularly important due to their high reactivity and their contribution to the radical budget and secondary products formation. However, previous research has primarily focused on a limited number of OVOCs species from pine, spruce, and other biofuels, leading to insufficient studies on the full mass spectra of OVOCs from biomass smokes. Our study has addressed this gap by identifying approximately 750 OVOCs from burning typical Chinese crop straws and woods. We found that C1–C3 organic acids and dicarboxylic acids are the predominant contributors to total signal intensities. This expands on previous studies that have focused on a limited well‐known molecular markers of biomass burning, such as monosaccharide, guaiacol and syringol derivatives, and reveals the presence of nitrogen‐containing compounds, including isocyanate, amide, amino acids, and pyridine. The saturation concentrations of organic compounds are estimated, highlighting the importance of semi‐volatile and intermediate VOCs (S/IVOCs) in fresh smoke releases. Our study contributes to a better understanding of complex chemistry of biomass burning and its impact on air quality. It will serve as a crucial basis for accurately assessing biomass burning related‐secondary organic aerosol formation. Key Points: C1–C3 organic acids and dicarboxylic acids dominate the total signal intensities of fresh crop straw and wood burning emissionsThe mass spectral profiles are largely similar across different fuels, with wood burning produces higher contributions of large compoundsSemi‐volatile and intermediate volatile organic compounds predominate fresh smoke emissions, with only a small fraction of low‐volatility compounds [ABSTRACT FROM AUTHOR]

Orange peel and sugar beet pulp contain large quantities of pectin, which can be turned via galactaric acid into furan dicarboxylic acid (FDCA) and its esters. In this work, we show the polymerisation of these FDCA esters into high‐molecular‐weight, 70–100 kg/mol, poly(ethylene 2,5‐furanoate) (PEF). PEF is an emerging bio‐based alternative for poly(ethylene terephthalate) (PET), widely used in for example packaging applications. Closing the loop, we also demonstrated and confirmed that PEF can be hydrolysed by enzymes, which are known to hydrolyse PET, back into FDCA for convenient recycling and recovery of monomers. [ABSTRACT FROM AUTHOR]

Guar gum is a specialty galactomannan that serves as an abundant, renewable and sustainable feedstock. Nevertheless, its films cannot be used for sustained drug delivery due to certain drawbacks such as susceptibility towards microbial contamination, high swelling rate, non-porous structure, and brittleness. Therefore, functionalization of galactomannan has been achieved by crosslinking with malonic acid, a green, water-soluble, simple organic dicarboxylic acid with minimum chain length possessing natural plasticizer properties using a green chemistry approach. Interestingly, malonic acid also acts as an auto catalyst during acylation and subsequent crosslinking. The reaction conditions were optimized by varying the concentrations of malonic acid (0.5%, 1.5%, and 2% w/v), temperature (55 °C, 100 °C, 120 °C, and 140 °C) and time (5, 10, and 15 min) to introduce 1,3-propane dioates in the galactomannan chains resulting in flexible crosslinked films of galactomannans. Furthermore, the effect of low and high curing temperatures on crosslinking has been investigated by the analysis of the degree of crosslinking for the first time. The mechanism of crosslinking with a dicarboxylic acid has also been proposed. Detailed analysis of films has been achieved by NMR (1D & 2D), FTIR, XRD, TGA and DSC. Furthermore, curcumin has been loaded in these crosslinked films and kinetic studies via the Korsmeyer--Peppas model demonstrate that curcumin has a non-Fickian diffusion controlled release (DCR) mechanism. The antibacterial, antifungal and antioxidant studies show that the prepared formulation has potential utility in sustained drug delivery and other biomedical applications. Altogether, these studies provide a foundation to develop a sustained drug release system using crosslinked films for wound healing, anticancer therapy and many more. [ABSTRACT FROM AUTHOR]

BODIPY based molecules functionalized with water soluble moieties have been developed and recognized as liable triplet photosensitizers for phototherapeutic applications. In this work, we have prepared BODIPY analogues with dicarboxylic acid groups and bearing iodine or fullerene moieties for efficient intersystem crossing which display far‐red absorption band and high singlet oxygen production both in organic and aqueous media. In this perspective by using similar design the effect of the halogenation of the dyes versus spin converter on the skeleton were compared. The structures of the synthesized BODIPYs and BODIPY‐C60 (6–10) were elucidated by mass, 1H and 13C NMR spectroscopic techniques. Photophysical and photochemical properties of the compounds were examined using UV‐Vis. absorption and fluorescence emission spectrophotometers. The absorption intensities of the trap molecules (DPBF and ADBA) reduced because of singlet oxygen generation in the media. This study may provide useful infrastructure to elucidate the relationship between the use of fullerene (9) or iodine (10) where singlet oxygen quantum yield of 9 and 10 are determined as 0.87 and 0.97 respectively. [ABSTRACT FROM AUTHOR]

A family of silver(I) and copper(I) complexes containing carboxylate ligands were prepared from the corresponding carboxylic acids and Ag2O. The compounds were characterized by various spectroscopic methods and X-ray diffraction. In the solid state, the silver(I) salts are coordination polymers based on dinuclear silver species with bridging carboxylate ligands. The reaction of these silver salts with Ph3P gives four-coordinate, tetrahedral bis(phosphine) complexes. Analogous copper(I) bis(phosphine) compounds were prepared by the reduction of copper(II) carboxylates with Ph3P. Decomposition temperatures and thermal decomposition products were studied by TGA/DSC measurements. The metal compounds decomposed cleanly to their respective metals (silver or copper) at temperatures ranging from 206 to 338 °C. [ABSTRACT FROM AUTHOR]

Metal‐organic frameworks (MOFs) have been widely studied as electrocatalysts, and the research strategy to improve their electrocatalytic oxygen evolution reaction (OER) performance is to modify their structure. In this paper, two‐dimensional bimetallic MOFs were constructed to improve electrocatalytic OER performance. Using a mild electrochemical method with Ni and Co as metal sources and 4, 4 ′‐biphenyl dicarboxylic acid (H2BPDC) as ligand, two‐dimensional NiCo‐BPDC was synthesized and then deposited on a carbon cloth electrode. The results show that NiCo‐BPDC/CC possessed a low overpotential of 356 mV at a current density of 20 mA cm−2 with a small Tafel slope of 86 mV dec−1 in 1.0 M KOH solution. The two‐dimensional NiCo‐BPDC exhibits excellent electrocatalytic OER performance because the coordination of Ni and Co in the material and the interaction of the two‐dimensional materials provide a large electrochemically active surface area and expose more metal active sites for OER, thus improving the reaction efficiency and indicating NiCo‐BPDC as potential OER electrocatalyst. [ABSTRACT FROM AUTHOR]

2-Pyrone-4,6-dicarboxylic acid (PDC), a chemically stable pseudo-aromatic dicarboxylic acid, is a promising building block compound for manufacturing biodegradable polyesters. This study aimed to construct high-performance cell factories enabling the efficient production of PDC from glucose. Firstly, the effective enzymes of the PDC biosynthetic pathway were overexpressed on the chromosome of the 3-dehydroshikimate overproducing strain. Consequently, the one-step biosynthesis of PDC from glucose was achieved. Further, the PDC production was enhanced by multi-copy integration of the key gene PsligC encoding 4-carboxy-2-hydroxymuconate-6-semialdehyde dehydrogenase and co-expression of Vitreoscilla hemoglobin. Subsequently, the PDC production was substantially improved by redistributing the metabolic flux for cell growth and PDC biosynthesis based on dynamically downregulating the expression of pyruvate kinase. The resultant strain PDC50 produced 129.37 g/L PDC from glucose within 78 h under fed-batch fermentation conditions, with a yield of 0.528 mol/mol and an average productivity of 1.65 g/L/h. The findings of this study lay the foundation for the potential industrial production of PDC. • Biosynthesis of PDC from glucose was achieved in E. coli by combinatorial pathway engineering. • Heterologous expression of hemoglobin was used to increase PDC production. • Dynamic downregulation of pykA was employed to balance cell growth and PDC biosynthesis. • An efficient cell factory enabling potential industrial production of PDC was constructed. [ABSTRACT FROM AUTHOR]

Two new zinc(II) complexes, [Zn2(PBM)2(terephthalate)(formate)2] (1) and {[Zn(PBM)(fumarate)]∙H2O}n (2), were synthesized using 1,3-bis(1H-benzo[d]imidazol-2-yl)propane (PBM) and two different dicarboxylic acids under solvothermal conditions. Complexes 1 and 2 have been characterized by infrared spectroscopy, elemental analysis, and single-crystal X-ray diffraction analysis. The structural analysis showed that 1 was a binuclear structure and then formed a 3D supramolecular network structure through hydrogen bond and π-π conjugation, while 2 was a one-dimensional coordination polymer. In 1 and 2, the zinc ions were four-coordinate with an N2O2 donor set and a slightly distorted tetrahedral geometry. The solid-state fluorescence properties indicate that the fluorescence peaks belong to the π*-π transition of the ligand PBM, which has a significant red shift and enhancement with the order being 1 > 2 > PBM. The stronger fluorescence of the complexes than the ligand is due to the immobilization of the ligand through coordination, which reduces the energy loss of thermal vibration. The π∙∙∙π conjugation in 1 results in a stronger fluorescence of 1 than 2. Therefore, coordination and π∙∙∙π conjugation will affect the fluorescence of complexes. [ABSTRACT FROM AUTHOR]