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Polyurethane (PU) stands out as a crucial category of polymers which have become indispensable in improving our quality of life, revolutionizing various aspects of human existence. However, this convenience comes with a dark side – the environmental impact associated with its disposal. Nevertheless, recycling presents a promising solution, aligning with the principles of a circular economy by transforming polymer waste into new materials. A notable focus within this realm is the utilization of dicarboxylic acids (DA) as depolymerization agents, achieved through a process known as acidolysis. This method has proven to be an exceptional solution, primarily explored for recycling PU foams and subsequently employed in the production of new foams. The resulting recycled polyol finds successful applications in various PU products, including rigid and flexible foams, adhesives, and coatings. Analyzing the impact of recycled polyol on the properties of new PU products reveals interesting insights. While it slightly affects the morphology and color of foams, there is no significant impact on density or thermal conductivity. Notably, flexible foams exhibit increased stiffness when produced using recycled polyol. Additionally, the strength of PU adhesives and the surface hardness of PU coatings are enhanced with the incorporation of recycled polyol, albeit with a reduction in gloss. The recycled PU coatings also display a more hydrophobic surface. Considering both environmental and economic benefits, the advantages of this approach are evident. With the aim of catering to the needs of both the academic and industrial sectors, this review delves into the subject of PU recycling via acidolysis, subsequently exploring the utilization of recycled materials in the creation of new PU products. The review offers an in-depth explanation of the acidolysis process and thoroughly examines the degradation mechanisms involved. Additionally, it scrutinizes the impact of reaction conditions on the properties of the recycled materials and investigates their applicability in the production of novel materials. Moreover, the review presents an analysis of the environmental and economic implications associated with these processes. In summary, this review overviews the current status of acidolysis of PU and prospects for its future. [ABSTRACT FROM AUTHOR]

The composition of aerosols influenced by regional pollution sources during a post-monsoon haze event was studied including the isotopic, bulk, and molecular signatures. The air mass back trajectory and fire spot analysis revealed that the Delhi aerosols were influenced by the regional post-harvest crop (rice plant) residue-burning activities during the sampling period. To better understand the atmospheric processes during such an event, three samples of 4 h duration each (Period I: from 06:00–10:00, Period II: 10:00–14:00, and Period III: 14:00–18:00 h local time) were collected during the sampling period (8th -17th November, 2019) in the daytime. The average mass concentration of PM2.5, molecular compounds including the inorganic and carbonaceous components (dicarboxylic acid class compounds), along with the stable isotopes of C and N were observed to be elevated during Period I of the study. NH4+ and SO42− were found to be the most abundant inorganic ions during Period II and III with Cl− being the dominant ion during Period I. The OC/EC, WSOC/EC ratios indicated the influence of biomass burning on Delhi aerosols with little influence of local ageing processes evident from the minimal variation observed between the three periods of study during the day. High concentrations of dicarboxylic acids than previous studies are reported with oxalic and succinic acid being the most abundant diacids, a typical behaviour observed in biomass-burning influenced aerosols with an interesting observation of terephthalic acid to be found in an appreciable amount. The δ15 N of TN and δ13 C of TC signatures clearly indicated the influence of emissions from the burning of a C3 plant on the aerosols. The results strongly suggested that the aerosols were influenced by biomass-burning activities in the neighbouring regions and were aged during the atmospheric transport over to the city of Delhi with minimal effect of local ageing processes during the study period. [ABSTRACT FROM AUTHOR]

Zinc metal–organic frameworks have emerged as promising candidates, demonstrating excellent biological properties stemming from the unique characteristics of MOFs and zinc. In this study, we employed a facile method to synthesize a zinc metal–organic framework [Zn(IP)(H2O)] using ultrasound irradiation, with the linker being isophthalic acid (IPA) (1,3-benzene dicarboxylic acid). The parent Zn-MOF and two Ag/Zn-MOF samples prepared via loading and encapsulation methods were comprehensively characterized using various techniques, including FT-IR, XRD, SEM, TEM, N2 adsorption–desorption isotherm, UV–vis spectroscopy and TGA. The parent Zn-MOF and two Ag/Zn-MOF samples exhibited a broad spectrum of antibacterial effects. Remarkably, genomic DNA of P. aeruginosa was effectively degraded by Zn-MOF, further supporting its potent antibacterial results. The free radical inhibition assay demonstrated a 71.0% inhibition under the influence of Zn-MOF. In vitro cytotoxicity activity of Zn-MOF against HepG-2 and Caco-2 cell lines revealed differential cytotoxic effects, with higher cytotoxicity against Caco-2 as explored from the IC50 values. This cytotoxicity was supported by the high binding affinity of Zn-MOF to CT-DNA. Importantly, the non-toxic property of Zn-MOF was confirmed through its lack of cytotoxic effects against normal lung cell (Wi-38). The anti-inflammatory treatment of Zn-MOF achieved 75.0% efficiency relative to the standard Ibuprofen drug. DFT and docking provided insights into the geometric stability of Zn-MOF and its interaction with active amino acids within selected proteins associated with the investigated diseases. Finally, the synthesized Zn-MOF shows promise for applications in cancer treatment, chemoprevention, and particularly antibacterial purposes. [ABSTRACT FROM AUTHOR]

Aldehyde dehydrogenases (ALDHs) represent a superfamily of enzymes, which oxidize aldehydes to the corresponding acids. Certain families, namely ALDH9 and ALDH10, are best active with ω-aminoaldehydes arising from the metabolism of polyamines such as 3-aminopropionaldehyde and 4-aminobutyraldehyde. Plant ALDH10s show broad specificity and accept many different aldehydes (aliphatic, aromatic and heterocyclic) as substrates. This work involved the above-mentioned aminoaldehydes acylated with dicarboxylic acids, phenylalanine, and tyrosine. The resulting products were then examined with native ALDH10 from pea and recombinant ALDH7s from pea and maize. This investigation aimed to find a common efficient substrate for the two plant ALDH families. One of the best natural substrates of ALDH7s is aminoadipic semialdehyde carrying a carboxylic group opposite the aldehyde group. The substrate properties of the new compounds were demonstrated by mass spectrometry of the reaction mixtures, spectrophotometric assays and molecular docking. The N-carboxyacyl derivatives were good substrates of pea ALDH10 but were only weakly oxidized by the two plant ALDH7s. The N-phenylalanyl and N-tyrosyl derivatives of 3-aminopropionaldehyde were good substrates of pea and maize ALDH7. Particularly the former compound was converted very efficiently (based on the kcat/Km ratio), but it was only weakly oxidized by pea ALDH10. Although no compound exhibited the same level of substrate properties for both ALDH families, we show that these enzymes may possess more common substrates than expected. [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]

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]

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]

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: 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]

Reversible networks of epoxidized natural rubber (ENR) mixed with dicarboxylic acid were studied. ENR is a bio-based polymer, commercially available, and capable of sulphur vulcanisation. In addition, ENR has been already reported to exhibit self-healing characteristics after ionisation by adding ionic groups to the epoxide group. The reversible network structure plays an essential role for self-healing behaviour, which cannot be obtained for elastomers with irreversible sulphur network. In this study, dicarboxylic acid was used to construct the reversible network. The reversible hydrogen bonds were established in such a way that firstly one carboxyl group of di-carboxylic acid (DA) is reacted to ENR and secondary the other carboxyl group of DA interacts with residual carboxyl group to form hydrogen bonds in carboxylic dimer. The self-healing behaviour was evaluated for ENR with DA by tensile tests. This self-healing system provides new insights for sustainable and natural-based materials. [ABSTRACT FROM AUTHOR]

Three different types of Zr-based MOFs derived from benzene dicarboxylic acid (BDC) and naphthalene dicarboxylic acid as organic linkers (ZrBDC, 2,6-ZrNDC, and 1,4-ZrNDC) were synthesized. They were characterized using X-ray diffraction analysis (XRD), X-ray photoelectron spectroscopy (XPS), Fourier-transform IR spectroscopy (FT-IR), and Transmission electron microscopy (TEM). Their hydrophilic/hydrophobic nature was investigated via contact angle measurements; ZrBDC MOF was hydrophilic and the other two (ZrNDC) MOFs were hydrophobic. The three MOFs were combined with MWCNTs as electrode modifiers for the determination of a hydrophobic analyte, flibanserin (FLB), as a proof-of-concept analyte. Under the optimized experimental conditions, a significant enhancement in the oxidation peak current of FLB was observed when utilizing 2,6-ZrNDC and 1,4-ZrNDC, being the highest when using 1,4-ZrNDC. Furthermore, a thorough investigation of the complex oxidation pathway of FLB was performed by carrying out simultaneous spectroelectrochemical measurements. Based on the obtained results, it was verified that the piperazine moiety of FLB is the primary site for electrochemical oxidation. The fabricated sensor based on 1,4-ZrNDC/MW/CPE showed an oxidation peak of FLB at 0.8 V vs Ag/AgCl. Moreover, it showed excellent linearity for the determination of FLB in the range 0.05 to 0.80 μmol L−1 with a correlation coefficient (r) = 0.9973 and limit of detection of 3.0 nmol L−1. The applicability of the developed approach was demonstrated by determination of FLB in pharmaceutical tablets and human urine samples with acceptable repeatability (% RSD values were below 1.9% and 2.1%, respectively) and reasonable recovery values (ranged between 97 and 103% for pharmaceutical tablets and between 96 and 102% for human urine samples). The outcomes of the suggested methodology can be utilized for the determination of other hydrophobic compounds of pharmaceutical or biological interest with the aim of achieving low detection limits of these compounds in various matrices. [ABSTRACT FROM AUTHOR]

Rainfall and land-use interactions drive temporal shifts in suspended sediment sources, yet the magnitude of such changes remains poorly understood due to the lack of land-use specific source tracers. We investigated α,ω-dicarboxylic fatty acid root-specific biomarkers, as diagnostic tracers for apportioning sources of time-integrated suspended sediment samples collected from a grassland dominated agricultural catchment in the southwest of England during the wet winter period. Applying fatty acids-specific stable carbon isotope analysis and a Bayesian isotope mixing model, we show that stream banks contributed most of the sediment in the early winter, i.e. October–December, while winter cereal-dominated arable land contributed more than half of the sediment during the late winter, i.e. January–March. The dominant sediment source shifted in conjunction with a period of prolonged consecutive rainfall days in the later period suggesting that intervention required to mitigate soil erosion and sediment delivery should adapt to changing rainfall patterns. Our novel findings demonstrate that isotopic signatures of α,ω-dicarboxylic fatty acids are promising tracers for understanding the resistance of agricultural soils to water erosion and quantifying the interactive effects of extreme rainfall and land use on catchment sediment source dynamics. [ABSTRACT FROM AUTHOR]

Background: Researchers, prompted by the toxicity and side effects associated with cisplatin, are exploring alternative approaches for developing transition metal-based anticancer agents. Employing a green biochemical approach, we transformed Nickel pyridine dicarboxylic acid compounds into the nanoscale using the aqueous extract of Macrotyloma uniflorum (horse gram). Results: Characterization of the biosynthesized nanoparticles involved electronic and IR spectroscopy. A scanning electron microscope revealed a predominant spherical shape for most Nickel nanoparticles (Ni-NPs), with XRD patterns indicating particle sizes ranging from approximately 30–150 nm. The nanoparticles were evaluated for their free radical scavenging efficiency and in vitro anti-malignant properties against HeLa and A549 cancer cell lines. Numerical optimization of the DPPH and MTT assays was conducted using response surface methodology (RSM), focusing on the effects of 3,4-pyridine dicarboxylic acid (ML1), 2,4-pyridine dicarboxylic acid (ML2), nickel nanoparticles concentration, and temperature. In this investigation, the incorporation of Horse Gram seed extract (Macrotyloma uniflorum) has unveiled its abundance in phenolic and flavonoid compounds, widely acknowledged for their robust antioxidant activity in the existing literature. Conclusion: The present study highlights the potential for refining the bio-toxicity and biochemical attributes of Ni-NPs to pave the way for a new generation of versatile anticancer agents with clinically established efficacy. Notably, the anticipated data closely corresponds with experimental outcomes, reinforcing the trustworthiness and validity of the RSM model for examining anticancer and antioxidant properties in this context. ML2 exhibited heightened antioxidant and anticancer activities in comparison to ML1 nanoparticles. [ABSTRACT FROM AUTHOR]

Microsphere 3D structure of Cu/Mn3O4@SC composite was fabricated by pyrolyzing the bimetallic CuMn-MOF, which was composed of Cu2+, Mn2+ and sulfur-containing ligand 2,5-thiophene dicarboxylic acid (H2TDC). The composite of Cu/Mn3O4@SC is used as a high-performance anode material for the lithium-ion batteries cycle exhibiting stable capacities of 715 mAh g−1 after 100 cycles at 200 mA g−1 and outstanding long cycle performance with a reversible capacity of 508 mAh g−1 at 0.5 A g−1 after 500 cycles. The superior performance for the Cu/Mn3O4@SC anode is mainly attributed to the mutual supporting characteristics of heterojunction synergistic effect, thus avoiding damage in the process of energy storage process. In addition, the kinetic analysis based on CV reveals that the transport kinetics mechanism of the Cu/Mn3O4@SC is synergistically controlled by the surface capacitive and pseudocapacitive behaviors. The EIS proves that the introduction of Cu enhances the conductivity of the material and the rate of lithium-ion diffusion. Cu- and S-doped multielement microspheres was fabricated by pyrolyzing CuMn-MOF supported by 2, 5-thiophene dicarboxylic acid. [ABSTRACT FROM AUTHOR]

Elemental doping can improve the photocatalytic activity of bulk graphitic carbon nitride (g-C3N4) under visible-light. In this study, sulfur and oxygen co-doped g-C3N4 (x% S-g-C3N4) was fabricated through thermal polymerization of macromolecular precursor obtained from hydrothermal pretreatment. The prepared photocatalysts, including g-C3N4, hydrothermally treated g-C3N4 (g-C3N4-HT), and x% S-g-C3N4, were analyzed under various conditions. Their ability to reduce Cr(VI) through photocatalytic reduction was evaluated comprehensively, taking into account the influence of catalyst dose, presence of inorganic anions, initial concentration and initial pH of Cr(VI) solution. The results showed that x% S-g-C3N4 (3% S-g-C3N4) possesses superior photocatalytic reduction activity to g-C3N4 and g-C3N4-HT, largely due to the co-doping. This co-doping strategy enhances the light harvesting capacity by modifying the electronic band structure of g-C3N4, and accelerates the excitons transfer and separation by optimizing its photoelectric properties. Additionally, the three-dimensional structure formed during preparation process enhances the stability and reusability of g-C3N4. [ABSTRACT FROM AUTHOR]

Itaconate is an unsaturated dicarboxylic acid that is derived from the decarboxylation of the Krebs cycle intermediate cis-aconitate and has been shown to exhibit anti-inflammatory and anti-bacterial/viral properties. But the mechanisms underlying itaconate's anti-inflammatory activities are not fully understood. Necroptosis, a lytic form of regulated cell death (RCD), is mediated by receptor-interacting protein kinase 1 (RIPK1), RIPK3, and mixed lineage kinase domain-like protein (MLKL) signaling. It has been involved in the pathogenesis of organ injury in many inflammatory diseases. In this study, we aimed to explore whether itaconate and its derivatives can inhibit necroptosis in murine macrophages, a mouse MPC-5 cell line and a human HT-29 cell line in response to different necroptotic activators. Our results showed that itaconate and its derivatives dose-dependently inhibited necroptosis, among which dimethyl itaconate (DMI) was the most effective one. Mechanistically, itaconate and its derivatives inhibited necroptosis by suppressing the RIPK1/RIPK3/MLKL signaling and the oligomerization of MLKL. Furthermore, DMI promoted the nuclear translocation of Nrf2 that is a critical regulator of intracellular redox homeostasis, and reduced the levels of intracellular reactive oxygen species (ROS) and mitochondrial superoxide (mtROS) that were induced by necroptotic activators. Consistently, DMI prevented the loss of mitochondrial membrane potential induced by the necroptotic activators. In addition, DMI mitigated caerulein-induced acute pancreatitis in mice accompanied by reduced activation of the necroptotic signaling in vivo. Collectively, our study demonstrates that itaconate and its derivatives can inhibit necroptosis by suppressing the RIPK1/RIPK3/MLKL signaling, highlighting their potential applications for treating necroptosis-associated diseases. [ABSTRACT FROM AUTHOR]

A process for synthesizing UV-curable ester/acrylate precursors from dicarboxylic acid mixtures, oxidized chemical recycling products of HDPE milk bottles, has been developed. The behavior and properties of the non-purified oxidized products were compared to its commercial diacid single components in producing the precursors. Two as-received oxidized products obtained at different conditions, i.e., Oxi-1 and Oxi-2, containing molar compositions of succinic acid (C4): glutaric acid (C5): adipic and longer dicarboxylic acids (C6+) of 55: 23: 22 and 67: 9: 24, were employed. The precursors were produced at high yields by end-capping the carboxylic groups with hydroxyethyl acrylate, utilizing p-TSA catalyst and MEHQ radical scavenger. With 5 mol% p-TSA and 3 wt% MEHQ, a reaction at 120 °C for 2 h was effective for synthesizing the precursors from Oxi-1, Oxi-2, and succinic acid. However, the optimal condition for adipic acid was at 140 °C for 4 h, implying lower esterification reactivity due to its longer methylene sequence. All ester/acrylate precursors were fully cured under UV lights within 10 min. DMA results of cured films from neat precursors (100CL-series) indicate that those derived from longer diacids yielded crosslinked networks with relatively lower Tg and rubbery plateau. However, when only 10% of the precursors were used as crosslinkers for acrylic acid/ethyl-hexyl acrylate (10CL-series), the influence of the starting material's diacid composition on the film's properties was lowered. The oxidized products from the nitric oxidation of HDPE have a high potential as value-added starting materials for UV-crosslinkers comparable to those from pure commercial diacids. [ABSTRACT FROM AUTHOR]

The influence of UV-Vis and monochromatic radiation (λ = 408 nm) on the reactions of copper sulfate (CuSO4) and copper(II) oxide (CuO) with β-diketones, chelators, and dicarboxylic acids was studied. The reactions of CuSO4 and CuO with Trilon B and succinic acid in aqueous media in the presence of urea occurred faster by using UV-Vis radiation. UV radiation accelerated the reaction of CuSO4 with H4edta in aqueous MeCN. Monochromatic radiation hastened the reaction of CuO with Trilon B and H4edta in aqueous and MeCN media. Eight reactions that were significantly accelerated by electromagnetic radiation were found. [ABSTRACT FROM AUTHOR]

This work highlights the importance of renewable materials, specifically polymers derived from epoxidized oils, in promoting sustainable development and reducing the environmental impact of various industries. The use of carboxylic acids as hardeners for biobased resins from epoxidized oils is also discussed as a promising development in this field. However, there is a lack of research in this area, and finding the right combination of carboxylic acids and epoxidized oils remains a challenge. The present work aimed to address this gap by synthesizing biobased resins using epoxidized soybean oil (ESO) and dicarboxylic acids with specific aliphatic chain lengths, such as oxalic, succinic, adipic and sebacic acids with 0, 2, 4 and 8 carbons in aliphatic chain. The curing and properties of the resulting biopolymers were investigated using DSC, FTIR, TGA, and swelling ratio assessments. FTIR spectra evidenced that the reaction between epoxy and carboxylic groups occurred by the presence of ester groups, as verified after the disappearance of the epoxy bands at ~ 829 cm−1 and the appearance of related bands to hydroxyl (-OH) at ~ 3500 and ester at 1685–1742 cm−1, respectively. DSC scans presented exothermic peaks related to the curing reactions associated to an increasing enthalpy (ΔH) as the aliphatic chain size increases. The activation energy, Eac, estimated using Friedman and Vyazovkin approaches, is highly influenced by the chain size and pKa of the acids. Furthermore, the thermal and hydrocatalytic degradation increase with the decrease of aliphatic chain. The study also introduces oxalic acid as a biobased cross linker for ESO, which has not been so far combined without any synthetic modifications in its structure. [ABSTRACT FROM AUTHOR]

The conditions for recording electrospray ionization mass spectra of dicarboxylic acids are selected to ensure the generation of doubly-charged negative ions of compounds containing more than 14 carbon atoms in the chain. The fragmentation of such ions under the conditions of collision-induced activation is described. It is shown that the main decomposition route is associated with the break of C–C bonds in the hydrocarbon skeleton of molecules. Thus, in contrast to the fragmentation of singly charged negative ions, the forced decomposition of bis-deprotonation products of decarboxylic acids makes it possible to obtain information about the structure of the molecular skeleton. [ABSTRACT FROM AUTHOR]

Using three different synthetic methods, 48 monoalkyl esters of 6 aliphatic dicarboxylic acids and 8 aliphatic alcohols were synthesized. Despite the method of synthesis, monoalkyl alkanedioates occurred in reaction mixtures along with corresponding dialkyl esters. This was caused both by a reaction mechanism and by possible secondary bimolecular disproportionation in solutions. However, for example, unlike monoalkyl phthalates, monoalkyl esters of aliphatic dicarboxylic acids appeared to be stable during their gas chromatographic separation. In no cases, characteristic chromatographic profiles indicating the decomposition of analytes in the chromatographic column were observed. The simultaneous presence of mono- and dialkyl esters in the samples allowed us to use the correlation of retention indices of mono- and dialkyl esters for their identification because the latter were characterized in more detail, namely, with RI(monoester) = aRI(diester) + b and some similar relations. The chromatographic peaks of monoalkyl alkanedioates (like for all carboxylic acids) on columns with nonpolar stationary phases were highly asymmetric. Their electron ionization mass spectra naturally indicated the presence of no signals of molecular ions. Mass spectra of monomethyl and monoethyl esters differed markedly from those of corresponding dialkyl esters, but they were similar for alcohols with R ≥ C3H7. [ABSTRACT FROM AUTHOR]

It is shown that the yield of micronization products in a supercritical antisolvent (SAS) precipitation can be used for a qualitative assessment of the solubility of substances in CO2–solvent mixtures. Assumptions for this approach are considered and recommendations are made to increase the accuracy of the assessment using this approach. The effect of the degree of supersaturation of the CO2–solvent–substance being micronized system on the morphology and size of particles of malonic and succinic acids micronized by the SAS method is studied. The possibility of obtaining α-succinic acid by the SAS method is demonstrated. [ABSTRACT FROM AUTHOR]

The work presents an approach for studying the kinetics, mechanism, and reactivity of intermediates of a wide class of redox reactions for which the rate-limiting step is the redox decomposition of the intermediate complex. The approach was applied to the investigation of the oxidation of oxalic acid (H2Ox) by cerium(IV) in a sulfuric acid medium as part of the Belousov–Zhabotinsky oscillating reaction (BZ reaction) catalyzed by cerium ions. Experimental, mathematical, and computational methods that are typically used to study metal complexes in a stable oxidation state were kinetically generalized to variable-valence metal complexes and were used to determine the characteristics of intermediate complexes of the cerium(IV)–oxalate reaction and derive a general equation for its rate based on a set of equations describing the rapid achievement of pre-equilibrium in the system and the subsequent nonequilibrium process. A quantitative model of the process was proposed; it included two parallel reaction pathways, for which two different cerium(IV)–oxalate intermediate complexes were identified and characterized. The complexes have similar reactivity, which may be due to the similarity of the structure of their inner coordination spheres and the inner-sphere mechanism of electron transfer in the complexes. Using the developed model, a diagram of the yields of all main species of cerium(IV) under the conditions of the BZ reaction was constructed, which indicates the need to take into account the formation of intermediate complexes of the composition CeOHOx (n = 1, 2) in the oxidation of oxalic acid under these conditions. The main difference between the presented model of the cerium(IV)–oxalate reaction as part of the BZ reaction and the previous models is the explicit consideration of the participation of intermediate complexes of cerium(IV) with oxalic acid anions and sulfate background anions in the reaction. [ABSTRACT FROM AUTHOR]

New possibilities of the photochemical addition to fullerene С60 were demonstrated. Monosubstituted 1,9-dihydrofullerenes were obtained by irradiation of С60 in the presence of homologues of thiophene, pyridine, and naphthalene as well as esters of glutaric, phthalic, succinic, adipic, pyridinedicarboxylic acids and N-alkyllactam. The HC60 moiety is bound to the hydrocarbon part of the organic fragment. The product of the methyl glutarate addition was reduced by bis(arene)chromium to give a new ion-radical salt. [ABSTRACT FROM AUTHOR]

People have become conscious about recycling or reusing many things they use in the 21st century because diminishing vital resources make it necessary, both personally and socially. The evaluation of waste is also critical in terms of national economies. In this study, starch dicarboxylic compounds were synthesized using waste potato peels (WPP) in the presence of sodium hypophosphite monohydrate as a catalyst for the formation of the ester cross-links. Adipic acid, succinic acid, and glutaric acid were employed with waste potato starch (WPS) to obtain cross-linked samples: WPS-A, WPS-S, and WPS-G, respectively. The obtained compounds were characterized by attenuated total reflectance Fourier transform infrared (FTIR-ATR), scanning electron microscopy with energy-dispersive X-ray analysis (SEM-EDX), X-ray diffraction (XRD), and their cytotoxicity properties were investigated. The biocompatibility of the obtained WPS-dicarboxylic acid compounds against NIH-3T3 and L929 murine fibroblast cells with MTT assay was determined. Studies have shown that these compounds do not harm healthy cells and are found to be bioavailable. [ABSTRACT FROM AUTHOR]

Two Al-MOFs, i.e., MIL-53 (Al) and (NH2)-MIL-53 (Al) have been synthesized using aluminium nitrate as metal ligands and 1,4 benzene dicarboxylic acid, amino 1,4 benzene dicarboxylic acid as organic linkers in aqueous medium at room temperature, respectively. Both Al-MOFs have been confirmed through different microscopy and spectroscopy tools. Afterwards, the optical properties of Al-MOFs have been confirmed in polar and non-polar solvents using photoluminescence spectroscopy. Finally, both Al-MOFs have been explored for optical nitrobenzene (NB) sensing. Interestingly, we have found excellent optical ability of NH2-MIL-53 (Al) over MIL-53 (Al) due to structural π–π* transitions. The photo-induced electron transfer mechanism has been found during the MOF–analyte interaction. Importantly, we confirmed that NH2-MIL-53 (Al) is an excellent sensing material for NB with a 0.28 ppb limit of detection over MIL-53 (Al). [ABSTRACT FROM AUTHOR]

Petroleum-based polyesters are widely used in daily life. However, their reliance on petroleum resources and non-biodegradability have raised concerns. Due to the advantages of being renewable, degradable, and abundant, bio-based polyester is expected to become a breakthrough in replacing petroleum-based polyester. In this study, p-hydroxybenzaldehyde, a bio-based monomer, was used to synthesize a novel diol, 2,2′-(4-((4-ethylphenyl)diazenyl)phenylazanediyl)diethanol (EDPD). The EDPD was then polymerized with 1,4-cyclohexanedimethanol (CHDM) and aliphatic diacids to synthesize a series of aliphatic-aromatic polyesters. Thermal analysis showed that the Tg varied from 43°C to 104°C, while the melting point (Tm) varied from 118°C to 156°C. All the polyesters exhibited high yield strengths (48–79 MPa) and tough values (elongation at break of 240–330%). After 30 weeks of soil incubation, the mass loss of the copolyester could reach 4.3%. The investigation of the eco-toxicity of the copolyesters showed that the survival rate of Eisenia foetida was more than 80%, demonstrating their low toxicity in natural habitats. The copolyesters investigated in this study exhibited good thermal, mechanical, and biodegradability properties. The properties of the copolyesters can be adjusted by varying the length of the carbon chains of the dicarboxylic acid moieties. These bio-based copolyesters could provide an important way to promote carbon neutrality and sustainable development of bio-based plastics. [ABSTRACT FROM AUTHOR]

New possibilities of the photochemical addition to fullerene С60 were demonstrated. Monosubstituted 1,9-dihydrofullerenes were obtained by irradiation of С60 in the presence of homologues of thiophene, pyridine, and naphthalene as well as esters of glutaric, phthalic, succinic, adipic, pyridinedicarboxylic acids and N-alkyllactam. The HC60 moiety is bound to the hydrocarbon part of the organic fragment. The product of the methyl glutarate addition was reduced by bis(arene)chromium to give a new ion-radical salt. [ABSTRACT FROM AUTHOR]

Aim: This systematic review and meta-analysis was conducted to synthesize the efficacy and safety of bempedoic acid in patients requiring lipid-lowering therapy. Methods: PubMed, Embase, and Scopus databases were searched for randomized controlled trials from inception till June 2023. The primary outcome was major adverse cardiovascular events (MACE), and secondary outcomes were all-cause mortality, serum lipid profile, and adverse events between bempedoic acid and comparators. ROB2 was used for risk of bias assessment. We pooled mean differences or relative risks (RR) along with 95% confidence intervals (random-effects model). Results: Five-hundred and thirty-one studies were screened and 17 (n = 21,131) were included for review. There was a significant reduction in the risk of MACE [RR, 0.88 (95% CI: 0.77 to 0.99), p = 0.03)] and all-cause mortality [RR, 0.90 (95% CI: 0.82 to 0.98), p = 0.02] following bempedoic acid treatment. Treatment with bempedoic acid led to a significant reduction in the mean serum total cholesterol [− 34.41 mg/dl (95% CI: − 42.43 to − 26.39), p < 0.001], low-density lipoprotein cholesterol (LDL-C) [− 33.91 mg/dl (95% CI: − 39.66 to − 28.17), p < 0.001], as well as high-density lipoprotein cholesterol (HDL-C) [− 2.40 mg/dl (95% CI: − 3.09 to − 1.71), p < 0.001] levels. However, there was a significant increase in the risk of hyperuricemia [RR, 2.05 (95% CI: 1.81 to 2.33), p < 0.001] following bempedoic acid treatment. The number needed to harm was large for all safety outcomes. The GRADE of evidence was moderate for all outcomes. Conclusion: Bempedoic acid reduces the risk of MACE and all-cause mortality, lowers serum total cholesterol and LDL-C levels, and has a favorable safety profile. Trial registration ClinicalTrial.gov Identifier: CRD42023412837. [ABSTRACT FROM AUTHOR]

Polyurethanes (PU) are unique heteropolymers with a wide range of physicomechanical properties, fields of use and high development potential. PU is obtained by condensation of diisocyanate and various polyol compounds. The peculiarities of the structure and synthesis of commercial polyols based on the products of secondary oil processing, namely oligomeric glycols, oxides and dicarboxylic acids are presented. [ABSTRACT FROM AUTHOR]

Aim: Bempedoic acid has shown noteworthy progress in the prevention and management of atherosclerotic cardiovascular disease (ASCVD) in recent years. However, there has been a lack of high-quality evidence regarding the risk reduction of clinical events with bempedoic acid. Therefore, the aim of this article is to conduct a comprehensive evaluation of the impact of bempedoic acid on the incidence of cardiovascular events. Methods: A systematic review and meta-analysis of randomized controlled trials pertaining to bempedoic acid was carried out. We conducted a systematic search across the Pubmed, Embase, and Cochrane Central Register of Controlled Trials databases to identify relevant studies published from inception to 23 April 2023. A total of four trials comparing the clinical benefit achieved with bempedoic acid versus placebo were included. Results: Our analysis comprised four trials that encompassed a total of 17,323 patients. In comparison to the placebo, bempedoic acid showed a significant reduction in the risk of major adverse cardiovascular events (MACE) [relative risk (RR), 0.86, 95% confidence interval (CI) 0.87–0.94]. Additionally, bempedoic acid substantially lowered the occurrence of fatal or nonfatal myocardial infarction (RR 0.76, 95% CI 0.66–0.89), hospitalization for unstable angina (RR 0.70, 95% CI 0.55–0.89), and coronary revascularization (RR 0.82, 95% CI 0.73–0.92). There was also a similar reduction in MACE in patients on the maximally tolerated statin therapy. Conclusion: Bempedoic acid may reduce the risk of cardiovascular events regardless of whether the patient is taking stains or not. Registration: PROSPERO registration number CRD42023422932. [ABSTRACT FROM AUTHOR]

Acyl-CoA-thioesterases, which hydrolyze acyl-CoA-esters and thereby release the respective acid, have essential functions in cellular metabolism and have also been used to produce valuable compounds in biotechnological processes. Thioesterase YciA originating from Haemophilus influenzae has been previously used to produce specific dicarboxylic acids from CoA-bound intermediates of the ethylmalonyl CoA pathway (EMCP) in Methylorubrum extorquens. In order to identify variants of the YciA enzyme with the capability to hydrolyze so far inaccessible CoA-esters of the EMCP or with improved productivity, we engineered the substrate-binding region of the enzyme. Screening a small semi-rational mutant library directly in M.extorquens yielded the F35L variant which showed a drastic product level increase for mesaconic acid (6.4-fold) and 2-methylsuccinic acid (4.4-fold) compared to the unaltered YciA enzyme. Unexpectedly, in vitro enzyme assays using respective M.extorquens cell extracts or recombinantly produced thioesterases could not deliver congruent data, as the F35L variant showed strongly reduced activity in these experiments. However, applied in an Escherichia coli production strain, the protein variant again outperformed the wild-type enzyme by allowing threefold increased 3-hydroxybutyric acid product titers. Saturation mutagenesis of the codon for position 35 led to the identification of another highly efficient YciA variant and enabled structure-function interpretations. Our work describes an important module for dicarboxylic acid production with M. extorquens and can guide future thioesterase improvement approaches. Key points: • Substitutions at position F35 of YciAHI changed the productivity of YciA-based release of carboxylic acid products in M. extorquens AM1 and E. coli. • YciAHI F35N and F35L are improved variants for dicarboxylic production of 2-methylsuccinic acid and mesaconic acid with M. extorquens AM1. • In vitro enzyme assays did not reveal superior properties of the optimized protein variants. [ABSTRACT FROM AUTHOR]

The stereoselective synthesis of (5Z,9Z)-tetradeca-5,9-diene-1,14-dioic acid was carried out using Ti-catalyzed homo-cyclomagnesiation of 2-(hepta-5,6-dien-1-yloxy)tetrahydro-2H-pyran. Intermolecular esterification of this dicarboxylic acid with polyether acetylenic alcohols in the presence of carbodiimides was used to synthesize the corresponding monoesters and symmetric diesters. Using the intramolecular oxidative coupling of terminal triple bonds of the latter compounds, polyether macrodiolides containing 1Z,5Z-diene and 1,3-diyne fragments were synthesized. [ABSTRACT FROM AUTHOR]

Pairs of α-carbanions generated from lithium 2-methylpropanoate, butanoate, pentanoate, hexanoate, heptanoate, and phenylacetate by the action of lithium diisopropylamide on the corresponding acids (AH, BH) in THF reacted with 1,2-dibromoethane to give mixtures of oxidative homo- (2,2,3,3-tetramethyl-, 2,3-diethyl-, 2,3-dipropyl-, 2,3-dibutyl-, 2,3-dipentyl-, and 2,3-diphenylbutanedioic acids) and heterocoupling products (3-ethyl-2,2-dimethyl-, 2-ethyl-3-propyl-, 2-butyl-3-ethyl-, 2-ethyl-3-pentyl-, 2-ethyl-3-phenyl-, 2-butyl-3-propyl-, 2-pentyl-3-propyl-, 2-phenyl-2-propyl-, 2-butyl-3-pentyl-, 2-butyl-3-phenyl-, and 2-pentyl-3-phenyl-butanedioic acids) in overall yields of 83–99%. The ratio of the homo- and heterocoupling products depended on the structure of the initial α-carbanions. [ABSTRACT FROM AUTHOR]

Pretreatment is a necessary step to converting lignocellulosic biomass from its native form into a more accessible form for the value-added utilization of its main components. Herein, we developed a one-step acid bleachable pretreatment method using a recyclable acid hydrotrope (p-toluenesulfonic acid, p-TsOH) and chlorate to achieve the fibers bleaching and lignin extraction simultaneously. Under a pretreatment condition of a p-TsOH concentration of 80 wt.%, a pretreatment temperature of 80 °C, and a pretreatment time of 45 min, 84.33% of hemicelluloses and 76.79% of lignin were dissolved out from poplar wood. The obtained dispersed solids with a whiteness of 60.13% can be used for papermaking or ethanol production. The results from quasi-simultaneous enzymatic saccharification and combined fermentation (Q-SSF) of the pretreated substrate indicated that the ethanol concentration and yield reached to 39.30 ± 0.57 g/L and 82.36 ± 1.15%, respectively. According to the results of lignin characterization, the aromatic rings in extracted lignin were opened forming dicarboxylic acids as well as derivatives due to the oxidation effect of chlorate, which is beneficial for its catalytic upgrading and composites preparation. Therefore, this study is important to valorization of lignocellulosic biomass. [ABSTRACT FROM AUTHOR]

Using a solvothermal method, we have synthesized two coordination polymers of Cu(II). One is a 1D polymer {[Cu(bpy)(NDC)(H2O)]·2H2O}n (1, 1D) formed with 1,8-naphthalene dicarboxylic acid (H2NDC) and 2,2′-bipyridine (bpy) as an auxiliary ligand, while the other is a 2D polymer {[Cu3(TMA) (Imd)3]·5H2O·2DMF}n (2, 2D) formed with trimellitic acid (H3TMA) and imidazole (Imd) as an auxiliary ligand. Both coordination polymers 1 and 2 were formed through an in situ hydrolytic ring opening reaction of 1,8-naphthalic anhydride and trimelitic anhydride with bipyridine and imidazole ligands, respectively. The asymmetric unit of polymer 1 contains asymmetric η1 binding mode (one of the carboxylate) linking distorted square-pyramidal [Cu(NDC)(bpy)(H2O)]2+ coordination units. The syn-syn-η1:η1 linear polymeric conformation exist in the 1D coordination polymer with adjacent Cu...Cu distance is 6.849 Å. A chain of cyclic tetrameric water clusters is present between the stacked layers of the 3D supramolecular structure. The formation of the 3D supramolecular structure is guided by various weak interactions such as O–H...O, C–H...O, C–H...π and π...π interactions. The coordination polymer 2 forms 3D supramolecular architecture guided by various weak interactions such as O–H...O, C–H...O and N–H...O interactions. The crystal structures of both coordination polymers have been determined using single crystal X-ray diffraction and their structural features are described. [ABSTRACT FROM AUTHOR]

Tetraphenylethylene (TPE)-based ligands are appealing for constructing metal-organic frameworks (MOFs) with new functions and responsiveness. Here, we report a non-interpenetrated TPE-based scu Zr-MOF with anisotropic flexibility, that is, Zr-TCPE (H4TCPE = 1,1,2,2-tetra(4-carboxylphenyl)ethylene), remaining two anisotropic pockets. The framework flexibility is further anisotropically rigidified by installing linkers individually at specific pockets. By individually installing dicarboxylic acid L1 or L2 at pocket A or B, the framework flexibility along the b-axis or c-axis is rigidified, and the intermolecular or intramolecular motions of organic ligands are restricted, respectively. Synergistically, with dual linker installation, the flexibility is completely rigidified with the restriction of ligand motion, resulting in MOFs with enhanced stability and improved separation ability. Furthermore, in situ observation of the flipping of the phenyl ring and its rigidification process is made by 2H solid-state NMR. The anisotropic rigidification of flexibility in scu Zr-MOFs guides the directional control of ligand motion for designing stimuli-responsive emitting or efficient separation materials. Metal-organic frameworks (MOFs) with adjustable porosity and tunable functionality have attracted considerable attention, but the directional control of intermolecular and intramolecular motion of TPE-based ligands in the non-interpenetrated flexible MOFs has not yet been studied. Here, the authors report a non-interpenetrated tetraphenylethylene-based MOF with anisotropic flexibility. [ABSTRACT FROM AUTHOR]

The review presents a comparative analysis of promising homogeneous metal complex catalysts and the results of studies on the synthesis and determination of the structural characteristics of efficient catalysts for the oxidation of organic compounds with hydrogen peroxide Q3{PO4[WO(O2)2]4} (Q is the quaternary ammonium cation) by EXAFS, SAXS, NMR, Raman, and IR spectroscopy. The possibilities of using bifunctional homogeneous peroxopolyoxo metal complexes in combination with organic cations having quaternized nitrogen under conditions of phase transfer catalysis were considered using as an example the oxidation of organic compounds of various classes with hydrogen peroxide, forming aliphatic and aromatic epoxides, mono- and dicarboxylic acids, as well as biologically active compounds for medical and agroindustrial purposes. [ABSTRACT FROM AUTHOR]

Aliphatic polyesters were synthesized from 1,4-butanediol and predominantly renewable dicarboxylic acids containing even numbered carbons from 4 to 20 (succinic acid to eicosanedioic acid). Melt polymerizations were conducted up to 220 °C with titanium tetrabutoxide as polymerization catalyst. Two polymerization methods were applied: (1) stoichiometrically equivalent amounts of diol and diacid with 14 hours under argon followed by 10 hours under reduced pressure, (2) a 10 mol % excess of diol, with 6 hours under the inert gas and 6 hours under reduced pressure. Molecular weight properties were determined by size exclusion chromatography in chloroform and polystyrene as calibration standards. For the polyesters with the C6 to C20 diacids, Mw obtained by Method 1 lied between 15,800 to 31,200 g/mol, and for Method 2 between 27,000 and 180,400 g/mol (average of Mw for PBS was 194,000 g/mol). 1H NMR and 13C NMR spectra of all polymers were obtained, peak assignments were made and the microstructure of the polymers was verified. In addition, peaks associated with end-groups were identified. Thermal properties of the polymers were determined by differential scanning calorimetry, dynamic mechanical analysis and thermal gravimetric analysis. For the polyesters obtained with C6 to C20 diacids, the highest Tg was 1.25 °C (from tan δ) and the highest Tm was 88.8 °C, both with the C20 diacid. The polymers were also treated by vacuum ultraviolet (VUV) photo-oxidation as a plasma surface modification. The wettability of the original polymers and after their VUV photo-oxidation was measured by contact angle goniometry with water. [ABSTRACT FROM AUTHOR]

Daytime and nighttime PM10 samples were collected during summer (June) and winter (February) at a representative urban site in Mumbai, located on the western coast of Indian subcontinent. Samples were studied for molecular distribution of water-soluble dicarboxylic acids, oxoacids and dicarbonyls as well as total carbon (TC), water-soluble organic carbon (WSOC), inorganic ions along with specific markers (levoglucosan, K+) to better understand sources and formation processes of organic aerosols in Mumbai. The distribution of water-soluble organics was characterised by high abundance of oxalic acid (C2), followed by phthalic (Ph), terephthalic (tPh), azelaic (C9), malonic (C3), and succinic acids (C4). Positive correlations between C2, sulfate and glyoxal (ωC2) suggest secondary production of C2 predominantly via aqueous phase chemistry. C2 also showed positive correlation with K+ and levoglucosan indicating that biomass/biofuel burning is the potential source of diacids in the Mumbai aerosols. In addition, higher average contributions of total diacids to WSOC and OC in winter than in summer suggest that aerosols were aged i.e., photochemically well processed in winter in Mumbai. On the other hand, diurnal change in their ratios is observed with higher ratio in daytime samples than that of previous and succeeding nighttime samples, suggesting diacids are also influenced from local sources in both the seasons. This study demonstrates that biomass burning as well as biogenic sources are important sources influencing the distributions of aerosols in Mumbai. [ABSTRACT FROM AUTHOR]

A series of dinuclear metallacycles of Mn(II), Co(II), Ni(II), Cu(II) and Cd(II) with 1,8-naphthalene dicarboxylic acid (H2NDC) with co-ligand such as 2,2′-bipyridine (bpy) or solvent molecules have been synthesized in a refluxed condition. One mononuclear Ni(II) complex has also been synthesized following the same synthetic procedure with NDC, bpy and pyridine. Among them two polymorphic structures have been isolated. The single crystal X-ray structures of all the metallacycles have been described along with Hirshfield surface analysis. [ABSTRACT FROM AUTHOR]

Comparative analysis was carried out to determine the variation in the composition of essential oils of hairy roots produced in vitro and in vivo rhizomes of Valeriana jatamansi Jones collected from three different districts in Nepal i.e., Pyuthan (1200 m), Gulmi (3000 m), Godawari (1400 m) was carried out. In vitro adventitious root proliferation was established in MS media supplemented with Naphthalene acetic acid (NAA). GC–MS analysis were performed on the essential oils extracted from the sample. The findings showed that the yield of the essential oil obtained from the hydrodistillation of in vitro adventitious roots and dried rhizomes ranged between 0.52 and 0.80%. The highest percentage of essential oil (0.80%) were produced in the in vitro adventitious roots and minimum in the in vivo rhizomes collected from Pyuthan district, i.e., (0.52%). GC–MS analysis revealed a total of 17 volatile compounds in the essential oil from the dried rhizomes of V. jatamansi Jones from different locations and in vitro adventitious roots. It was found that the compound carotol was present only in sample from Pyuthan district, but absent in other samples. The compound matricarin was found in samples from Gulmi and Godawari district but absent in samples from Pyuthan district and in vitro adventitious roots. Similarly, the compound jatamansone was found in samples from Gulmi, Godawari, and adventitious roots but absent in sample from Pyuthan district. The compounds patchoulinone, 1, 2-butyl octyl ester of benzene dicarboxylic acid, and bis (2-ethyl hexyl) phthalate, one of the major compounds were present only in sample from adventitious roots The findings of the present study showed that the essential oil composition in both in vitro and in vivo roots, at different altitudes significantly affect the essential oil content of V. jatamansi Jones. [ABSTRACT FROM AUTHOR]

This study assessed the emissions of gaseous pollutants and particle size distributed water-soluble organics (WSO) from a diesel vehicle fuelled with ultralow sulphur diesel (B0) and 10 (B10), 20 (B20), and 30% (B30) biodiesel blends in a chassis dynamometer tested under transient mode. Particulate emission sampling was carried out in an ultraviolet (UV) test chamber using a 10-stage impactor. Samples were grouped into three size fractions and analysed by gas chromatography-mass spectrometry. Increasing the biofuel ratio up to 30% in the fuel reduced WSO emissions by 20.9% in comparison with conventional diesel. Organic acids accounted for 82–89% of WSO in all tested fuels. Dicarboxylic acids were the most abundant compound class, followed by hydroxy, aromatic, and linear alkanoic acids. Correlations between compounds demonstrated that adding biodiesel to diesel fuel reduces the emissions of nitrogen oxides (NOx), benzene, toluene, ethylbenzene and xylenes (BTEX), methane (CH4), total and nonmethane hydrocarbons (THC and NMHC), and dicarboxylic and hydroxy acids, but increases emissions of carbon dioxide (CO2) and alkanoic and aromatic acids. Emissions of dicarboxylic and hydroxy acids were strongly correlated with the biodiesel content. WSO emissions of coarse and fine (1.0–10 μm) particles decreased with the increasing biofuel content in fuel blend. The total share of ultrafine (0.18–1.0 μm) and nanoparticles (< 0.18 μm) increased in WSOs emissions from B20 and B30 blends, when compared with petrodiesel. The biodiesel content also affected the chemical profile of WSO size fractions. [ABSTRACT FROM AUTHOR]

Fumaric, malic and succinic acids have been selectively separated by facilitated pertraction with Amberlite LA-2, using n-heptane as liquid membrane. The feed phase consisted on viscous aqueous solution with similar mixture of carboxylic acids and viscosity as those of Rhizopus oryzae fermentation broth. Due to the differences between the acidities and molecule size of these acids, it is possible to selectively recover fumaric acid from the initial solution. The pH-gradient between the feed and stripping phases, as well as carrier concentration in the liquid membrane represent the main process parameters influencing the pertraction selectivity. Among them, Amberlite LA-2 concentration exhibits the most important control on the selectivity factor S, the maximum value of S being reached for carrier concentration of 30 g/l. The increase of feed phase viscosity amplified the magnitude of these influences on pertraction selectivity, due to the hindrance of acids diffusion towards the region where their reaction with Amberlite LA-2 occurs, effect more important for malic acid. Therefore, by modifying the viscosity from 1 to 24 cP, the maximum value of selectivity factor was increased from 12 to 18.8. [ABSTRACT FROM AUTHOR]

New heteroleptic metal-organic frameworks of lanthanides, units of which contain anionic organic ligands of two types, are prepared by the solvothermal synthesis in N,N-dimethylformamide (DMF). The cross-linked coordination polymer [Ho2(CA)2(Bdc)·4DMF] (I) and two scaffold derivatives [La2(pQ)2(Bpdc)·4DMF] (II) and [Ce2(CA)(Bdc)2·4DMF]·2DMF (III·2DMF), where CA is chloranilic acid dianion, pQ is 2,5-dihydroxy-3,6-di-tert-butyl-para-benzoquinone dianion, Bdc is terephthalic acid dianion, and Bpdc is 4,4'-biphenyldicarboxylic acid dianion, are synthesized. The structures of compounds I, II, and III·2DMF are studied by X-ray diffraction (XRD) (CIF file CCDC nos. 2212230, 2212231, and 2212232, respectively). [ABSTRACT FROM AUTHOR]

Fifteen new diazaadamantane derivatives containing phthalimide or succinimide moieties have been prepared by the reaction between recently prepared 2,5,7-substituted 6-oxo(hydroxy)-1,3-diazaadamantanes and anhydrides of different dicarboxylic acids. The products were tested for antibacterial activity. [ABSTRACT FROM AUTHOR]

A highly luminescent Ln-MOF [La3(NDC)4(DMF)3(H2O)4]n, (NDC = 2, 6 naphthalen dicarboxylic acid) was designed and synthesized. The structure was characterized by x-ray single structure determination, TGA, IR spectra and PXRD and fluorescence spectroscopy. The structure shows high fluorescence intensity based on the presence of lanthanide metal and ligand. In the presence of I−, the emission can be effectively quenched introducing turn off system. Furthermore, the synthesized Ln-MOF can recognize Hg (II) by showing fluorescence turn-on signal because of the high affinity between Hg (II) and I−. Moreover, the high selectivity and sensitivity of the synthesized Ln-MOF makes it quit qualified for determination of the low concentration of mercury (2.00 nM). [ABSTRACT FROM AUTHOR]

Potentiometric measurements were used to determine the stability constants of cobalt(II) complexes with a series of pyridine mono and dicarboxylic acids. The following pyridinecarboxylic acids were used: pyridine-2-carboxylic acid (also known as picolinic acid (HPic, HL)), pyridine-3-carboxylic acid (also known as nicotinic acid (HNic, HL)), and pyridine-4-carboxylic acid, known as isonicotinic acid (HIso, HL), the 2-chloropyridine-3-carboxylic acid (HCl-Nic, HL), pyridine-2,6-dicarboxylic acid known as dipicolinic acid (H2Dipic, H2L), pyridine-2,4-dicarboxylic acid (H22,4-Dipic, H2L), pyridine-2,5-dicarboxylic acid (H22,5-Dipic, H2L) and pyridine-3,4-dicarboxylic acid (H23,4-Dipic, H2L). 1.0 mol·dm−3 NaNO3 was used as the ionic medium at 25 °C. Additionally, the hydrolytic cobalt(II) constants were determined under the same experimental conditions. A spectrophotometric study based on Job's plot and the molar ratio method was completed to validate the potentiometric measurements. [ABSTRACT FROM AUTHOR]

A series of Zn2+ based hydrophobic coordination polymers (CPs) have been synthesized by varying methylene spacers length (m = 1 to m = 6) of aliphatic dicarboxylic acids followed by reaction with the zinc acetate by using hydrothermal method. The synthesized CPs were coated on the mild steel (MS) specimens to investigate the effect of methylene spacers length of dicarboxylic acids on hydrophobicity and corrosion behavior. The synthesized CPs and their coatings on MS have been characterized by various instrumental techniques such as Fourier transform infrared (FTIR) spectroscopy, powder X-ray diffraction (PXRD), Field Emission Scanning Electron Microscopy (FE-SEM), water contact angle (WCA) measurements. FTIR and PXRD measurements confirm the formation of CPs whereas the FE-SEM images of suberic acid polymer (SUAP) reveal compact distribution of sphere-like aggregates. WCA measurements showed that the bare MS including CPs coatings on MS up to methylene spacers length m = 4 is hydrophilic in nature; however, the coating of longest methylene spacers length CP (SUAP, m = 6) showed hydrophobic nature with water contact angle of ~ 108.6°. Furthermore, the obtained hydrophobic SUAP CP with polyvinylidene fluoride (PVDF) as binder was coated on MS to study its anticorrosion behavior for the protection of MS. The anticorrosion performance of the developed SUAP coating was investigated by open-circuit potential (OCP) and potentiodynamic polarization techniques. The corrosion rate has been calculated from potentiodynamic polarization curves for the bare MS and SUAP coated MS showed significant improvement in the anticorrosion behavior of the developed SUAP coating. [ABSTRACT FROM AUTHOR]