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We describe a method for the differentiation of carboxylate anions on disposable paper supports (common printer paper, filter paper, chromatography paper), based on differential patterns of interactions between carboxylates and a fluorescent sensing system. The sensor was built from commercially available components, namely a polycationic fifth generation amine-terminated poly(amidoamine) dendrimer (PAMAM G5) and a small organic fluorophore (calcein) through non-covalent interactions. The assay’s physical dimensions were chosen to conform to the microwell plate standard so detection could be carried out on widely available plate reader instrumentation. The sensing complex was first deposited in spots on a paper support to prepare the sensor strip; a carboxylate solution was then loaded on each spot. Nuanced changes in fluorescence were associated with carboxylate binding to the PAMAM dendrimer, characteristic of the structure and affinity of each carboxylate. Such signal changes, interpreted through Linear Discriminant Analysis (LDA), contained enough information to recognize and successfully discriminate most anions in the panel. Among the substrates we tested, chromatography paper was the most promising. The relationship between the structure of the carboxylates and the patterns giving rise to their differentiation was also discussed. Finally, the long-term stability (“shelf life”) of the pre-assembled [calcein·dendrimer] sensing system was found to be excellent when deposited on paper support. [ABSTRACT FROM AUTHOR]

This paper describes a new option for integrated recovery and esterification of carboxylates produced by anaerobic digestion at a pH above the pK a . The carboxylates (acetate, propionate, butyrate, valerate and lactate) are recovered using a strong anion exchange resin in the bicarbonate form, and the resin is regenerated using a CO 2 -expanded alcohol technique, which allows for low chemicals consumption and direct esterification. Paper mill wastewater was used to study the effect of pH and the presence of other inorganic anions and cations on the adsorption and desorption with CO 2 -expanded methanol. Calcium, which is present in paper mill wastewater, can cause precipitation problems, especially at high pH. Esters yields ranged from 1.08 ± 0.04 mol methyl acetate/mol of acetate in to 0.57 ± 0.02 mol methyl valerate/mol of valerate in . [ABSTRACT FROM AUTHOR]

Papers and textiles that are treated with per- and polyfluoroalkyl substances (PFASs) are sources of human and environmental exposure. Data for individual PFASs, such as perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA), are not placed into the context of total fluorine for papers and textiles. Gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) were used to quantify volatile and ionic PFASs, respectively, and the total oxidizable precursor (TOP) assay was used to quantify precursors that form perfluoroalkyl carboxylates. Molar sums of PFASs obtained by GC-MS, LC-MS/MS, and precursors were compared to total fluorine (nmol F/cm²) determined by particle-induced gamma ray emission (PIGE) spectroscopy, measured before and after extraction. Volatile and ionic PFASs and unknown precursors accounted for 0-2.2%, 0-0.41%, and 0.021-14%, respectively, of the total nmol F/ cm² determined by PIGE. After extraction, papers and textiles retained 64 ± 28% to 110 ± 30% of the original nmol F/cm² as determined by PIGE, indicating that the majority of fluorine remains associated with the papers and textiles. The sum of PFASs in the volatile, ionic, and precursor fraction, and total fluorine after extraction indicate that mass balance was achieved (within analytical error) of the initial total fluorine measured by PIGE. [ABSTRACT FROM AUTHOR]

Although functionalized carbon-based materials have been widely used as the supercapacitor electrodes, the optimum contents of the functional groups, the charge storage mechanisms, and the effects of electrolytes and operating temperature have not yet been clearly investigated. In this work, carboxylate-modified hollow carbon nanospheres (c-HCN) with different functional group contents synthesized by an oxidation process of carbon nanospheres with nitric acid were coated on flexible carbon fibre paper and used as the supercapacitor electrodes. An as-fabricated supercapacitor of the c-HCN with a finely tuned 6.2 atomic % of oxygen of the oxygen-containing groups in an ionic liquid electrolyte exhibits a specific capacitance of 390 F g −1 , a specific energy of 115 Wh kg −1 , and a maximum specific power of 13548 W kg −1 at 70 °C. The charge storage mechanism investigated is based on the chemical adsorption of the ionic liquid electrolyte on the c-HCN electrode. This process is highly reversible leading to high capacity retention. The supercapacitor in this work may be practically used in many high energy and power applications. [ABSTRACT FROM AUTHOR]

The document is a contents list for the journal CrystEngComm, which focuses on the design and understanding of solid-state and crystalline materials. It includes a range of papers on various topics, such as photon upconversion, catalytic activity, structural diversity, and crystal stability. The journal is published by The Royal Society of Chemistry, a leading chemistry community. [Extracted from the article]

A novel 3D luminescent metal–organic framework (MOF) denoted as [Eu(BTA)0.5(H2BTA)0.5(H2O)]n (Cj-2) has been constructed from a π-conjugated ligand with a tetracarboxylate group, 1,2,4,5-benzenetetracarboxylic acid (BTA), via solvothermal synthesis. Structural analysis reveals that the Cj-2 framework is composed of tetranuclear secondary building units (SBUs) containing uncoordinated carbonyl groups which provide feasible recognition sites to interact with analytes. Cj-2 shows a trinodal (4,6,10)-connected 3D topological network consisting of tetranuclear SBUs. Cj-2 displays outstanding potential as a luminescent sensor for detecting o-NP and Cd2+ in DMF suspension, with remarkable sensitivity and selectivity through the luminescence quenching effect. Cj-2 displays excellent luminescence quenching behaviour in the presence of other competing interfering analytes and can be recycled at least four times for sensing o-NP and Cd2+. For Cd2+ ions, it is the host–guest interactions and for the nitroaromatic compounds, it is the competitive absorption of excitation energy and the electron transfer mechanism that are the probable mechanisms for such sensing processes. Moreover, visual fluorescent test papers based on Cj-2 were assembled and employed to selectively detect nitroaromatic compounds and metal ions. Based on the aforementioned results, Cj-2 can be considered as a potential luminescence sensor for detecting Cd2+ and o-NP. [ABSTRACT FROM AUTHOR]

Butler's Bader Award recognizes her research group's many significant contributions elucidating the bioinorganic chemistry of the marine environment, including the chemistry of siderophores and vanadium haloperoxidases. While vanadium is the second-most abundant transition metal ion in seawater, iron levels are extremely low over much of the world's ocean. The original version of this article was revised: In the original publication author name was incorrectly published as "Alison Butler" and this has been corrected as "Lawrence Que, Jr". [Extracted from the article]

The tetranuclear Cu2+/Ca2+/Ca2+/Cu2+ complex based on Malten ligand has been investigated as a platform for anion binding. Simple organic carboxylates and non‐steroidal anti‐inflammatory drugs (NSAIDs) have been tested, revealing the ability of the platform to bind them. The receiving platform hosts at least two guests in solution although a third anion can be bound, as suggested by X‐ray diffraction analysis. The addition of the anions is accompanied by a color change of the solution, making the system a colorimetric sensor for carboxylates (LOD values comprised between 3.6 and 20.7 ppm). A fluorescent system consisting of the 2‐(3‐oxido‐6‐oxoxanthen‐9‐yl)benzoate (fluorescein anion) linked to the tetranuclear platform has been also prepared and used in a chemosensing ensemble approach to signal the presence of the selected anions (Log K between 2.6 and 5.6 for the addition of two guests). The latter also works in a paper strip test, offering the chemosensor a possible practical application. [ABSTRACT FROM AUTHOR]

Although hydrogen-bonded organic frameworks (HOFs) have received particular attention in the field of proton conduction owing to their richly H-bonded networks and porous structures, there are few related reports, especially on the study of the related proton exchange membranes (PEMs). In this paper, a multi-pyridine and multi-carboxylate-based HOF (H3tpt = 4-(2,4,6-tricarboxyphenyl)-2,2′,6′,2′′-terpyridine, namely HOF 1) was successfully prepared and introduced in a chitosan (CS) matrix to fabricate proton-conductive composite membranes. Firstly, the excellent thermal-, water-, and acid-stability of HOF 1 were confirmed via various measurements. Secondly, an AC impedance test demonstrated its temperature- and humidity-dependent proton-conductive properties. Based on the above preliminary research, we tried to dope it into CS to prepare a composite membrane (denoted as CS/HOF-x , where x is the doping amount of 1 in the hybrid film). Fortunately, one composite membrane (CS/HOF-4) with ultra-high proton conductivity (σ) (2.61 × 10−2 S cm−1 under 100 °C and 98% RH) was fabricated using the casting method; its best σ value is 54 and 2 times greater than that of HOF 1 (4.83 × 10−4 S cm−1) and the pure CS membrane, respectively, and is comparable to that of Nafion under similar conditions. Further, the proton conduction mechanism of the HOF 1 composite membrane was proposed. This research represents the first time that HOF has been doped into CS to make a high-efficiency proton-conducting composite membrane, which will lay a good foundation for its application in fuel cells and other related fields. [ABSTRACT FROM AUTHOR]

The paper of van der Ent et al. (Plant Soil 485:247–257, 2023), published in the previous issue, reports the hyperaccumulation of rare earth elements (REE) in plant species from the Proteaceae for the first time. Indeed, the high REE accumulation in Proteaceae is not completely unexpected, given that the plants release large amounts of carboxylates to acquire phosphorus and micronutrients. However, it is somewhat questionable that the efficiency of element mobilization alone sufficiently explains the large variability in REE accumulation among different taxa of Proteaceae or other P-efficient species that typically show low concentrations of REE. Given that REE3+ share chemical similarities to Ca2+ but form stable complexes with ligands similar to Al3+, it is reasonable that uptake and accumulation of REE depend not solely on element mobility but also on the dynamics of element speciation governed by the formation, stability, and fate of carboxylate-REE-complexes in the rhizosheaths. The rationale behind this contention is that for elements with low mobility in soil, changes in chemical speciation may increase the availability only if the complex stabilities that depend on rhizosphere pH allow a breakdown during uptake. In this commentary, we explore the idea that REE accumulation depends on rhizosphere processes related to nutrient acquisition and element exclusion that overlap in time, space, and function depending on the composition of metal-chelating ligands released by plant roots in concert with rhizosphere pH. Based on data from greenhouse and field experiments, we propose a model where plants with a P-mining strategy (hyper)accumulate REE when rhizosphere pH is below a critical value shifting the REE speciation to available forms. [ABSTRACT FROM AUTHOR]

The paper presents the results of the study on the interaction of azido(benz)imidazo[2,l-b][l,3]thiazines with acetylene carboxylates under non-catalytic conditions according to Huguesgen. It was established that the [3+2]-cyclocondensation of the specified reagents occurs regioselectively upon heating and without the use of a catalyst with the formation of a 1,4-addition product, alkyl l-((benzo)imidazo[2,l-b][l,3]thiazine-6-yl)-lH-l,2,3-triazole-5-carboxylates 4a--g, the structure of which was thoroughly proved by the methods of *H (13C) NMR spectroscopy and chromatography-mass spectrometry. All obtained compounds were investigated in vitro experiments for antibacterial and antifungal activity. Based on the results of bioscreening, methyl l-(2,3-diphenyl-6,7-dihydro-5H-imidazo[2,l-b][l,3]thiazin-6-yl)-lH-l,2,3-triazole-5-carboxylate 4b, ethyl l-(2,3-diphenyl-6,7-dihydro-5H-imi dazo[2,l-b][ l,3]thiazin-6-yl)- 1H- 1,2,3- triazole- 5-carboxylate 4c, methyl l-(3,4-dihydro-2H- benz[4,5]imidazo[2,l-b][l,3]thiazin-3-yl)-lH- l,2,3-triazole-5- carboxylate 4e, tert-butyl l-(3,4-dihydro-2H- benz[4,5]imidazo[2, l-b][l,3]thiazine-3-yl)-lH-1,2,3-triazole-5- carboxylate 4g showed a bactericidal effect at a concentration of 31.25 mg/ml against the bacterium Proteus mirabilis. [ABSTRACT FROM AUTHOR]

This paper presents a preliminary scientific investigation of pigments used by Martiros Sarian, a prominent Armenian artist known for his vibrant and evocative paintings. The study focuses on five of Sarian's paintings from different periods of his career, namely, Morning in Stavrino, Arabian Dancer, Caravan, Yerevan Zangu River, and Kirovakan, dated between 1909 and 1948. Non-destructive techniques, including micro-attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopic imaging and X-ray fluorescence (XRF), were employed to characterize the pigments in the samples extracted from these paintings. The results reveal the presence of various pigments, including ultramarine blue, cobalt blue, cobalt cerulean blue, viridian, emerald green, cobalt green, celadonite green, cadmium yellow, chrome yellow, Venetian red, yellow ochre, red ochre, lead white, zinc white, and calcium carbonate. Additionally, metal carboxylates and oxalates, degradation products associated with the paint layers, were observed and discussed. The findings contribute to a better understanding of Sarian's artistic technique and provide valuable insights for the conservation and restoration of his artworks. [ABSTRACT FROM AUTHOR]

The paper proposes a method that exhibits operational simplicity for the indirect spectrophotometric determination of oxalate ion. We developed Reactive Blue 4 (RB4) as a sensor by complexation with copper ion as a simple, inexpensive yet selective colorimetric chemosensing ensemble for the recognition of oxalate over other available competitive analytes via indicator displacement assay (IDA) in both solution (aqueous medium) and solid state (paper-based experiment). The addition of oxalate to RB4-Cu2+ complex changed the colour from sky blue to dark blue due to the regeneration of RB4 by the chelation of oxalate as the competitive analyte with Cu2+. The absorbance band increase is linear with oxalate concentration from 1.76 to 49.4 µmol/L with a detection limit of 0.62 µmol/L. This measurement mode did not show any influence of interferences (available anions and ascorbic acid). This approach eliminated the need for the separation stages, enzymatic multiple-step reactions, sample preparation, organic solvent mixture, chemical modifications and equipment developed to a high degree of complexity. The oxalate determination gave results in different real samples such as urine, mushroom and spinach, which demonstrated the applicability of the existing method. Furthermore, this colorimetric system can serve as IMPLICATION molecular logic gate using Cu2+ and oxalate (C2O42-) as inputs and UV-Vis absorbance signal as the output with potential monitoring applications. [ABSTRACT FROM AUTHOR]

Blue dyes are relatively uncommon in nature, and a novel dithiophene dye (RanB) is reported in this paper. This dye is derived from an old anti-osteoporotic drug and is a metal ion complexing agent, displaying a planar molecular structure, with two sets of carboxylate, isonitrile, thiophene, and iminodiacetate groups. The blue color originates from a strong absorption peak at 648 nm, accompanied by an unusual fluorescence at 555 nm, with higher energy compared to the main absorption band. RanB forms complexes with lanthanoid ions through the iminodiacetate groups and serves as an effective sensitizer for Tb3+ ions, heightening their emission and improving their use as luminescent agents. Its photo-physical properties and the interaction with Tb3+ have been investigated using absorption spectroscopy, steady-state and time-resolved fluorescence spectroscopy, along with computational methods (ZINDO/S and DFT). The RanB toxicity in human umbilical vein endothelial cells has also been tested, showing a lack of toxicity, holding promising prospects for application as a luminescent and coloring agent in pharmaceuticals and food. [ABSTRACT FROM AUTHOR]

Saponification, resulting from pigment–binder interactions, is one of the most endangering phenomena affecting the appearance and stability of painted works of art. The crystallization of metal carboxylates (soaps) in paint layers is recently assumed as the most critical point for the development of undesirable changes induced by saponification, however, the factors triggering it are not fully understood. The red pigment cinnabar (HgS) has been suspected of contributing to saponification, however, the paucity of reliable reference structural data limited the experimental research of its effect at the molecular level. Within this study we synthesized mercury(II) carboxylates of the formula Hg(C16)x(C18)2−x (x = 0.0; 0.2; 0.5; 0.8; 1.0; 1.2; 1.5; 1.8; 2.0) where C16 and C18 are hexadecanoate (palmitate) and octadecanoate (stearate), respectively, and characterize them by combination of X-ray powder diffraction (XRPD) and 13C and 199Hg solid state NMR (ssNMR). For a more detailed interpretation of their structural and thermal behavior, Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) were used. The crystal structure of the studied mercury carboxylates was described on the basis of complementary ssNMR and XRPD measurements, Rietveld refinement and DFT calculations. All the subjected compounds crystallize in a monoclinic lattice of the C2/c symmetry. Mercury atoms are arranged in a slightly distorted square antiprismatic geometry and are monodentatically bonded to carboxylate anions. The structural disorder at the aliphatic end of the stearic acid chains was detected in the mixed carboxylates. Within the paper, the structural (dis)similarity with the corresponding lead carboxylates is discussed. The synthesized and characterized mercury carboxylates were applied to describe neo-formed mercury soaps in a model experiment simulating an egg-based paint system. [ABSTRACT FROM AUTHOR]

The ancient lacquer films excavated from Dongshan Han tomb M6 of the Western Han Dynasty in Taiyuan City, Shanxi, China, were found sensitive to pH variation. This paper aims to demonstrate the pH-dependent warping behaviors of the ancient lacquer film and discuss their mechanism. The samples were analyzed by surface analytical techniques including attenuated total reflectance-Fourier transform infrared spectroscopy and X-ray photoelectron spectrometry. The results suggest that the outer layer of the lacquer film is more oxidized than the inner layer and contains more carboxylates, with calcium ions and possibly ammonium cations as counter ions. The carboxylates are speculated to be formed by oxidative cleavages in the urushiol side chains and hydrolysis of glycerides of drying oils. The shrinkage and swelling of the lacquer film can be regulated by the type of cations (H+, Ca2+, Na+) of carboxylates through hydrogen bonds, coordination bonds and static forces. Due to the higher content of carboxylates in the outer part, it shrinks more at low pH causing warping outward and swells more at high pH causing warping inward. This paper may provide an important reference for pH control and help resolve the warping problem during conservation or restoration of ancient lacquerware. [ABSTRACT FROM AUTHOR]

Two novel luminescent Cd(II)–organic frameworks, [Cd2(2-abpt)(Hbtca)(H2btca)0.5(H2O)]n (1) and {[Cd3(2-abpt)(btca)1.5]·H2O}n (2) (2-abpt = 3,5-di(2 -pyridyl)-4-amino-1,2,4-triazole, H4btca = 1,2,4,5-benzenetetracarboxylic acid), were hydrothermally synthesized from a rigid aromatic carboxylate ligand and a pyridine ligand containing free amino groups. 1 exhibits a novel (4,4,5,5)-c 2D layer architecture with 1D pipe-like chains. 2 shows a 3D framework with an unprecedented (4,4,4,6,7)-c topology. Their structural differences mainly stem from the various coordination modes of the rigid aromatic carboxylate ligand. Luminescence sensing experiments exhibit that 1 can highly sensitively and selectively detect TNP in DMF and H2O. Moreover, test paper was developed to detect TNP as a convenient and practicable approach. In addition, 1 shows highly sensitive and selective sensing of Cu2+. The possible detection mechanisms of 1 towards TNP and Cu2+ have been discussed. These experimental results suggest that 1 should be a potential sensor for TNP and Cu2+. [ABSTRACT FROM AUTHOR]

A semi-flexible imidazole-based urea ligand, 1-(3-(1H-imidazol-1-yl)propyl)-3-phenylurea, and three zincdicarboxylate coordination polymers possessing the ligand were synthesized and characterized. The stoichiometry and coordination number of the zinc(II) ions in the coordination polymers were found to be dependent on the positional isomers of the benzene dicarboxylate. The 1,3-benzenedicarboxylate-based coordination polymer has a one-dimensional structure, whereas, the one possessing 1,4-benzenedicarboxylate has a two-dimensional architecture. The solvent used in the synthesis of the zinc-1,3-benzenedicarboxylate coordination polymer with the ligand played a decisive role on the solvation and conformation of the ligand. The anhydrous form was obtained from a reaction in methanol in which one of the urea moieties has a puckered geometry and the assembly has layers from one-dimensional bunches of coordination chains. However, the same reaction in ethanol provided a solvate having water and ethanol as the solvents of crystallization and it has the two ligands with a stretched geometry forming a cleft-like geometry to include the ethanol molecules. The two forms were not inter-convertible. The coordination polymer with 1,4-benzenedicarboxylate has a 2-dimensional structure with 2 × 2 grids having self-included urea that held DMF molecules by hydrogen bonds. [ABSTRACT FROM AUTHOR]

A new method for the efficient conversion of pyridine methanols and ethyl carboxylates to pyridine esters in air catalyzed by Novozym 435 (N435) was reported. The enzyme catalyzed transesterification reaction was performed under the optimum conditions: N435 (60 mg) as a biocatalyst, acetonitrile (2.5 mL) as a solvent, the molar ratio of pyridine methanols (0.2 mmol) to ethyl carboxylats (1.0 mmol) of 1 : 5, molecular sieve 3 A of 1.00 g, reaction temperature of 50 °C, the revolution speed of 150 rpm and reaction time of 36 h. The enzyme still retained a yield of 80 % after repeated use for 10 times. Under optimal conditions, eighteen pyridine esters were synthesized in this paper, containing fifteen esters as novel compounds. The synthesized pyridine esters were analyzed by gas chromatography‐mass spectrometry‐olfactory (GC‐MS‐O), of which four pyridyl esters including compounds 3 a, 3 c, 3 g and 3 r possessed strong aromas which were based on peak area in GC‐MS. Thermogravimetric analysis (TG) was performed on these four flavor compounds. According to the results of TG analysis, they had good thermal stability at the certain temperature. [ABSTRACT FROM AUTHOR]

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Coordination polymers (CPs) in recent times have emerged as active constituents in many semiconductor devices like light emitting diodes (LED), field effect transistors (FET), photovoltaic devices and Schottky barrier diodes. An intelligent choice of linkers, careful selection of metal ions and post synthetic modification (PSM) can provide a better pathway for charge transportation. However, a proper understanding of the charge transport mechanism in CPs is still inadequate due to the lack of considerable experimental and theoretical work. In this paper, we address the theoretical elucidation of semiconducting properties and a probable pathway for charge transportation in three of our previously published CPs using density functional theory (DFT). These results help us to recognize the orbitals that have major contributions in the formation of the valence band and also provide the most likely pathway for optimum electronic communication. In this regard, the role of hydrogen bonding and unpaired electrons of metal d-orbitals is also established. [ABSTRACT FROM AUTHOR]

In this paper, gradient and block polycarboxylate ether superplasticizers (PCEs) composed of allyl alcohol polyoxyethylene ether macromonomer and acrylic acid were synthesized via aqueous reversible addition-fragmentation chain transfer (RAFT) polymerization. The molecular structure of PCEs was characterized by 1H nuclear magnetic resonance (NMR), Fourier transform infrared (FT-IR) spectroscopy, and size exclusion chromatography (SEC), and the fluidity of cement paste and the influence of SO42− on the dispersibility of PCEs were investigated in detail. The experimental results show that the molecular weight and polydispersity of the obtained PCEs were well controlled by the RAFT process. Compared with the PCEs prepared by conventional free radical polymerization, the gradient PCEs synthesized by RAFT polymerization exhibited excellent dispersion capability. The range of molecular weights and acid-ether ratios of the gradient PCEs for high fluidity of cement paste was much wider. Furthermore, PCEs with gradient structure also showed excellent sulfate resistance. In contrast, PCEs with block architecture exhibited the lowest flowability. Based on these findings, the relationship between dispersibility of PCEs and their chemical structures was illustrated. [ABSTRACT FROM AUTHOR]

Coordination bonding of Ni(II) tetraazamacrocyclic (TAMC) complexes to carboxylic groups of organic polymers and graphene oxide paper (GOP) is proposed for a facile generation of paramagnetic centers by combining two diamagnetic components. The coordination functionalization occurs under basic conditions in water solution at room temperature. The coordination configuration of central Ni(II) changes from tetracoordinated square-planar to hexacoordinated pseudooctahedral, which implies the conversion from low-spin to high-spin nickel centers. In the case of organic polymers, the coordination bonding of Ni(II) macrocycles gives rise to characteristic changes in coloration (from yellow-orange to violet-blue), as well as clearly manifests itself in UV–visible, FTIR and EPR spectra. In the case of GOP, in addition to evident changes in FTIR spectra, morphological alterations in the mat surface and an increase in the mat thickness are observed in SEM images, which can be explained by an intercalating effect of voluminous macrocyclic cations, as well as by partial disintegration of GOP structure due to the liquid-phase treatment. The effective magnetic moments of tetraazamacrocycles attached to organic polymers vary from 0.88 to 1.47 BM, whereas for GOP considerably higher values of 2.10 and 2.87 BM were obtained. [ABSTRACT FROM AUTHOR]

In this paper, three isostructural 1D lanthanide complexes, [Ln(dppc)(H2O)4]n·2nH2O (Ln = Eu, Tb and Eu0.501Tb0.499, named 1-Eu, 2-Tb and Eu0.501Tb0.499), based on 3-(2,4-dicarboxylate phenyl)-2-pyridinecarboxylic acid (H3dppc) have been synthesized and characterized by elemental analysis, IR, PXRD, TG and X-ray crystallography. The complexes exhibit a 1D chain structure, which is further linked into a 3D supramolecular framework by hydrogen bonds. Tuneable emission colour of Eu0.501Tb0.499 is realized by adjusting the excitation wavelength. The sensing properties of 1-Eu and 2-Tb towards Fe3+ and aniline indicate that the two complexes have almost the same superior sensitivity and low detection limit for Fe3+ in aqueous solution, while they have different detection abilities for aniline in DMF solvent. The different detection abilities were discussed by means of PXRD, UV-vis, luminescence lifetimes and molecular surface calculations (Hirshfeld surface analysis and 2D fingerprint plots). [ABSTRACT FROM AUTHOR]

In recent years, due to their tunable hierarchical architecture and wide versatility in applications, the synthesis of coordination polymers (CPs) has received wide attention from the scientific community. The present work focuses on the solvothermal synthesis of two novel lanthanoid CPs composed of gadolinium and dysprosium connected with 1H-pyrazole-3,5-dicarboxylic acid (1H-3,5-PDA) and benzene-1,4-dicarboxylic acid (1,4-BDC) linkers. The prepared materials were assessed using elemental analysis, SCXRD, FTIR, PXRD, thermogravimetric analysis and photoluminescence. The synthesized sensor (CP 2) is an efficient chemosensor for the detection of Fe3+ and meta-nitro aniline, thereby acting as a dual sensor. The material exhibits high quenching efficiencies of 98.25% and 98.11% towards the sensing at ppm-level concentrations of Fe3+ and m-NA, respectively. The Ksv values for the detection of Fe3+ and m-NA were found to be 3.76 × 104 L mol−1 and 2.5 × 104 L mol−1, respectively, which the confirm high and efficient sensing ability of the synthesized sensor. [ABSTRACT FROM AUTHOR]

The supramolecular organization of organic salts has been widely researched, revealing recurring patterns in crystalline lattices that describe their supramolecular properties. In recent years, our research group has underscored the importance of considering the crystalline structures as a whole, incorporating all the necessary energetic and topological information for a comprehensive understanding of the crystalline system. Given this context, we investigated a series of ammonium mono- and dicarboxylate salts (1–12) to determine whether subtle structural modifications in the anionic organic component lead to relevant energy and topology changes in the crystalline lattice. To achieve this, we selected structures whose carboxylate anion only possesses an alkyl chain and is devoid of other functional groups. The ammonium cation (NH4+) was fixed to determine the effect of variations in the alkyl chains of the selected mono- and dicarboxylates, such as length and degree of unsaturation. Additionally, probable crystallization mechanisms were proposed to elucidate some of the topological and energetic aspects involved in the crystallization of these compounds. Destabilizing interactions were observed in 10 crystalline structures, and the MEP data showed that the most destabilizing interactions occur by the proximity of portions with the same type of charge. Some dimers have unexpectedly low intermolecular interaction energies despite having large contact areas. Based on these data we demonstrate the additivity of intermolecular interactions, that is, the low intermolecular interaction energy in these dimers is the result of the sum of destabilizing energies and stabilizing energies. The cluster energy efficiency data revealed that most crystal lattices display typical characteristics of uncharged organic compounds. The proposed crystallization mechanisms showed a gradual increase in nucleus complexity in the initial stages and the total number of nucleation stages, resulting in five main patterns: monomer → 1D → 3D (1–2), monomer → dimer → 2D → 3D (3), monomer → 1D → 2D → 3D (4–5), monomer → dimer → 3D (6), and monomer → 2D → 3D (7–12). [ABSTRACT FROM AUTHOR]

Chiral nickel complexes containing NHC-carboxylate chelate ligands derived from the (S)-isomeric form of amino acids have been synthesised from the corresponding imidazolium salt and nickelocene. The presence of the carboxylate on the N-side arm of the heterocycle results in the competing formation of mixtures of mono- and bis-NHC complexes (i.e., [Ni(η5-Cp)(κ2-C,O-NHC)] and [Ni(κ2-C,O-NHC)2]), both of which retain the (S)-configuration of the stereogenic center and which can be separated by chromatography. Both the 18e− and 16e− complexes are found to be very stable and cannot be interconverted. The composition of the resulting mixtures depends mainly on the entity of the amino acid residue and, of more practical interest, on the reaction conditions. Thus, microwave heating and MeCN as a solvent favor the formation of the half-sandwich nickel complexes, rather than the bis-NHC compounds. Some of the [Ni(η5-Cp)(κ2-C,O-NHC)] complexes turn out to be among the best nickel catalysts for the hydrosilylative reduction of p-acetophenones described to date, although without chiral induction, in the absence of activating additives and under mild catalytic conditions. [ABSTRACT FROM AUTHOR]

The polycarboxylate superplasticizer with low molecular weight was synthesized via catalytic chain transfer copolymerization of polyethylene glycol monomethyl methacrylate (MAPEG) and methacrylic acid (MA) in this paper. Gel permeation chro matograph (GPC) tests confirmed the molecular weight of the synthesized polycarboxylate superplasticizer was as low as 7710 and the conversion rate of MAPEG 92.8%. Then adsorption experiment found that the low molecular weight polycarboxylate superplasticizer could keep continuous adsorption onto the cement particles for a long time. Finally the mortar and concrete tests indicated the low molecular weight polycarboxylate superplasticizer had a viscosity-reducing capacity in cement based materials. Meanwhile it had a long fludity retention capactiy, could keep the low-middle slumps concrete stable for at least 2h. [ABSTRACT FROM AUTHOR]

The paper reports the methods for the synthesis of new cluster compounds of trans-tetrachlorodi-μ-carboxylates of dirhenium(III) with dipeptides of the glycyl series. The compositions and the structures were determined by electron absorption and IR spectroscopies as well as by elemental analysis for the following newly synthesized compounds: trans-[Re2(H3N+- CH2-CO-NH-CH(COO)-CH2-CH(CH3)-CH3)2Cl4·2CH3CN]Cl2 (I) and trans-[Re2(H3N+-CH2-CO-NH-CH(COO)-CH2-C6H5)2Cl4·2CH3CN]Cl2 (II). Analysis of the electronic absorption spectra of the solutions of the synthesized substances showed the presence of a doublet pattern (12500 and 16129 cm-1), which corresponds to the δ→δ*-electronic transition of the Re-Re quadruple bond characteristic of solutions of trans-tetrachlorodi-μ-carboxylates of dirhenium (III). The appearance of oscillations at 1485 cm-1 for I and 1486 cm-1 for II, characteristic of the νs(CO) of the coordinated carboxylate group, was detected on the IR spectra, which indicates the bridging coordination of this group to the ... binuclear fragment. The protonation of the amino group is indicated by the appearance of a wide band of valence oscillations ... in the range of 3400-3350 cm-1 and deformation oscillations ... at 1557 cm-1 and 1614 cm-1 for I and II, respectively. The stability of the obtained complex compounds in aqueous solutions was determined. It was shown that the hydrolysis of the synthesized substances takes place in 4-5 days, which is accompanied by a decrease in the pH of the reaction solution. [ABSTRACT FROM AUTHOR]

Polyoxometalates (POMs) are commonly prepared using a “bottom-up” synthetic procedure. The alternative “top-down” approach of disassembling a pre-formed POM unit to generate new synthetic intermediates is promising, but relatively comparatively underused. In this paper, a rationale for the top-down method is provided, demonstrating that this approach can generate compounds that are fundamentally inaccessible from simple bottom-up assembly. We demonstrate this principle through the synthesis of a series of 10, new, mixed-metal, hybrid compounds with the general formula [TBA]2[MoVI10CoII6O30(RpPO3)6(RcCOO)2(L)x(H2O)6] (TBA = tetrabutylammonium, Rp = phosphonate moiety, Rc = carboxylate moiety, L = pyridyl ligand, and x = 2–4), including a one-dimensional polyoxometalate-based coordination polymer. We propose that these structures are generated from {MoxO3x−1} fragments that cannot be accessed from bottom-up assembly alone. The POM clusters are stabilised by three distinct classes of organic ligand – organophosphonate, carboxylate and pyridyl ligands – which can each be substituted independantly, thus providing a controlled route to ligand functionalisation. [ABSTRACT FROM AUTHOR]

The combination of nanoparticles and polycarboxylate ether superplasticizers is expected to simultaneously improve the durability and mechanical properties of mortar and concrete. However, the uniform dispersion of nanoparticles in cement materials has always been a difficult challenge. In this paper, nanoparticles are modified with surfactants to provide a research direction for better dispersion of nanoparticles in cementitious materials. Modified allyl ether polycarboxylate superplasticizer with short-branched chains was synthesized from acrylic acid and allyl glycidyl ether. Nano-silica/polycarboxylate ether was obtained by grafting nano-silica onto polycarboxylate ether molecular chains through intermolecular dehydration, thus achieving a homogeneous dispersion of nano-silica in the cementitious material. The results show that nano-silica/polycarboxylate ether has better dispersibility in cement matrix and strong clay resistance, which compensates for the poor dispersion of polycarboxylate ether synthesized from conventional polyethylene glycol graft chains in the presence of clay impurities. [ABSTRACT FROM AUTHOR]

In this paper, slump-preserving polycarboxylate superplasticizer (GPEG-PCE) was synthesized by free radical copoly merization reaction by ethylene glycol monovinyl polyethylene glycol ether (GPEG), acrylic acid, hydroxyethyl acrylate, and the redox system is hydrogen peroxide/E51 and molecular mass regulator mercappropylic acid (MPA). Discuss the effect of raw material ratio and synthesis process on its performance. The test results showed that the best reaction process parameters of GPEG-PCE are: the initial temperature is 20 °C, the ratio of acid to ether is 1.6, the ratio of ester to ether is 3.6, and the amount of initiator (H2O2) and molecular weight regulator (MPA) are 0.40% and 0.63% of macromonomer, respectively. The reaction time is 1 h. The synthesized GPEG-PCE has better dispersibility and slump retention than the slump-retaining polycarboxylate superplasticizer synthesized by HPEG/TPEG polyether monomer. GPEG-PCE and ordinary polycarboxylate superplasticizer are compounded and applied to concrete in a certain proportion, which can make the concrete slumps slightly increased within 3 h. [ABSTRACT FROM AUTHOR]

Ink‐jet printing of cellulosic fabrics with reactive dyes typically requires that the fabric is pretreated with alkali, prior to printing, to facilitate efficient fixation of the dye. In this paper we evaluate the use of sodium formate and other carboxylate salts as a neutral (pH 6.5) pretreatment process. The thickened, prepared‐for‐print pad liquor contained at least 50 gdm−3 of the selected carboxylate salt and was applied to the cotton fabrics by a pad‐dry procedure. The fabric was then ink‐jet printed with reactive dye inks, followed by standard steaming and washing‐off processes. The pH of the carboxylate salt pretreatment was 6.5 and the aqueous extracts from the print fabrics at the end of the steaming process remained at pH 6.5. It was observed that even at pH 6.5, in the presence of selected carboxylates, significant reactive dye fixation could be achieved on a cotton substrate, whereas in the absence of the carboxylate, very little or even zero fixation was achieved. Infrared and capillary electrophoresis analyses of model reactions of reactive dyes with the carboxylate salts indicated that reactive ester residues were formed, and which subsequently promoted reaction with the cellulosic substrates. In addition to improving reactive dye fixation in ink‐jet printing, the carboxylate‐modified dyes were also demonstrated to improve long‐liquor dyeing properties on cotton substrates. As an extension of this carboxylate‐based printing process, the incorporation of lithium acetate (100 gdm−3) into the ink formulation was further studied and it was demonstrated that the necessity for a preparative pretreatment process could be eliminated. [ABSTRACT FROM AUTHOR]

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Purpose This paper aims to investigate and prepare the composite polyurea greases with excellent thermal stability and tribological properties.Design/methodology/approach In this paper, composite Ba-based (Ba, barium) tetra-polyurea lubricating greases were prepared with two different methods: mixing Ba-based gelatinizer and tetra-polyurea gelatinizer by a physical method; and introducing barium carboxylate into tetra-polyurea molecules by a chemical method. The properties of the products, such as heat stability, water resistance and friction performance, were analyzed with thermogravimetry, water-resistance test and four-ball friction test.Findings The results indicated that the products obtained by chemically introducing barium carboxylate into tetra-urea molecules showed better elevated temperature tribological properties, and the disadvantages of the polyurea greases with high temperature hardening were also obviously improved. The cone penetration rate at 180°C for 24 h is only 3 per cent. The friction coefficient can be decreased to 0.44 and the last non-seizure load value was increased from 560 N to 1,120 N without any other additives.Originality/value The research is significant because the prepared composite grease showed excellent performances, such as the outstanding thermal stability, water resistance and excellent extreme pressure and anti-wear properties, which may be widely applied in steel, metallurgy, bearings and other industrial fields. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) capable of post-synthetic metalation (PSMet) have garnered significant interest as supports for catalytic metals. The Mn-based MOF, MnMOF-1 ([Mn3(L2Me)3] where L2Me = bis-(4-carboxyphenyl-3,5-dimethylpyrazolyl)methane), has been an exemplar for studying PSMet. Herein we investigate the synthesis of Mn-based MOFs from related flexible ditopic pyrazole carboxylate links, along with the formation of MOFs with similar tetratopic hinged linkers. We show for the first time that MnMOF-1 is likely a kinetic or metastable phase and a newly identified 2D layered material (MnMOF-2D) is the thermodynamically favoured product for this metal–linker combination. Formation of a MnMOF-1 structure with shorter linkers is thwarted by steric clashes that preclude the formation of the Mn3 cluster. This observation prompted the use of density functional theory (DFT) simulations that showed the target material to be very dense, highly strained and thereby energetically unfavourable, but potentially, a hypothetical MnMOF-1 structure with a longer phenylethynyl spacer would be energetically feasible. Finally, the predominance of 2D MOFs formed with shorter flexible links encouraged us to use tetratopic hinged linkers to form 3D frameworks, which was vindicated by the successful synthesis of two new porous 3D Mn-based MOFs, MnMOF-L4 and MnMOF-L5. These results highlight that reticular synthesis of MOFs formed with flexible, non-linear linkers is challenging. [ABSTRACT FROM AUTHOR]

Four new coordination polymers (CPs), namely, [Ni(H2L)1.5(1,10-phen)(H2O)2]n(1), {[Ni(H2L) (dib)]·2H2O}n(2), {[Ni(L)0.5(bix)]·H2O}n(3), and [Ni(L)(dpa)0.5(H2O)]n(4) (H4L = 5,5'-(ethene-1,2-diyl)diisophthalic acid; 1,10-phen= 1,10-phenanthroline; dib= 1,4-bis(1H-imidazol-1-yl)benzene; bix = 1-(4-((1H-imidazol-1-yl)methyl)benzyl)-1H-imidazole; and dpa = (E)-1,2-di(pyridin-4-yl)diazene), exhibit diverse coordination modes of the H4L ligand and fascinating crystal structures. Complex 1 displays a one-dimensional chain structure constructed from H2L2− ligands. 2 presents a 2D 2-fold interpenetrating framework, while 3 and 4 have similar 3D (4,6)-connected topology structures. Different auxiliary linkers may be able to induce different conformations and coordination modes of H4L and have an impact on the resulting networks, according to the structural variety of complexes. In addition, the magnetic properties of 1–4 were investigated in detail, which revealed that either weak ferromagnetic or antiferromagnetic interactions occurred between Ni(II) centers in 1–4. Hirshfeld surface analysis is employed to explore the noncovalent interactions that are responsible for crystal packing quantitatively. [ABSTRACT FROM AUTHOR]

A green and practical electrooxidation protocol for C3 acyloxylation of 2H-indazoles with carboxylic acids in the presence of potassium carbonate has been developed by intermolecular cross-dehydrogenative C(sp2)–O coupling. It is sustainable without the use of transition-metal catalysts, stoichiometric oxidants, and even extra supporting electrolytes. Potassium carbonate plays a key role in the reaction, and reacts with carboxylic acids to form carboxylates. Mechanistic studies by cyclic voltammetry and control experiments reveal that the reaction proceeds via an ECE mechanism. In addition, various carboxylic acids and 2H-indazoles are suitable in this system and provide a series of novel desired products at room temperature in an undivided cell. [ABSTRACT FROM AUTHOR]

Reactions of Co(II) salt and N,N′-di(4-pyridyl)sebacoamide (L1), N,N′-bis(4-pyridylmethyl)bicyclo(2,2,2,)oct-7-ene-2,3,5,6-tetracarboxylic diamide (L2) or N,N′-di(4-pyridyl)adipoamide (L3) with angular dicarboxylate ligands afforded coordination polymers (CPs) {[Co(L1)(OBA)(H2O)]·0.5H2O}n [H2OBA = 4,4′-oxybis(benzoic acid)], 1a, {[Co2(L1)(OBA)2]·3DMF}n, 1b, {[Co(L1)0.5(SDA)]·2H2O}n (H2SDA = 4,4′-sulfonyldibenzoic acid), 2a, {[Co2(L1)2(SDA)2(H2O)]·2H2O}n, 2b, {[Co(L1)0.5(MBA)]·H2O}n (H2MBA = diphenylmethane-4,4′-dicarboxylic acid), 3, {[Co(L2)(OBA)]·solvent}n, 4, {[Co(L2)(SDA)(H2O)]·solvent}n, 5, {[Co(L2)(MBA)(H2O)]·2H2O}n, 6, [Co(L2)(HFIPBB)(H2O)]n [H2HFIPBB = 4,4-(hexafluoroisopropylidene)-bis(benzoic acid)], 7, and {[Co(L3)(MBA)]·2H2O}n, 8. CPs 1a, 1b, 2a and 2b exhibit a 2D layer with an (84·122)(8)-22,4L2 topology, a 3-fold interpenetrated 3D net with a (412·63)-pcu topology, a 2D → 3D inclinedly polycatenated framework with a (42·68·8·104)(4)2-2,6L1 topology and a 2-fold interpenetrated 3D framework with a (48·67)-msw topology, respectively, and 3 displays a 2-fold interpenetrated 2D layer with a (42·68·8·104)(4)2-2,6L1 topology. CPs 4–6 are 2D layers, showing (64·8·10)(6)-2,4L3, (36·46·53)-hxl and (4·82)-fes topologies, respectively, whereas CP 7 displays a 3-fold interpenetrated 3D net with a (45·8)-dmp topology and 8 forms a 1D → 2D polycatenation with a (63·82·10)(6)2-2,2,4C5 topology. A structural comparison of 1–8 indicates that the flexibility of the bis-pyridyl-bis-amide plays an important role in the formation of entangled Co(II) CPs auxiliarily supported by the angular dicarboxylate ligand. [ABSTRACT FROM AUTHOR]

Abstract—In this paper, the possibility of enhancement of protective action of sodium oleate (SOl) toward Mg90 magnesium alloy is studied through its combined use with following sodium salts: oleyl sarcosine (SOs), mixture of alkenylsuccinic acids (SASA), and flufenamic acid (SFF). It is determined that introduction of 8 mM of most of the blends to the borate solution with 1 mM NaCl results in more effective inhibition of local depassivation of Mg90 than SOl at the same concentration. The highest anti-pitting basis is achieved upon addition of equimolar composition of SOl and SFF (2.40 V). By recording anodic polarization curves and tests in the humid atmosphere, the protection ability of the adsorption layers formed from aqueous solutions of 16 mM inhibitors and their blends is evaluated. It is shown that surface modification in SOl solutions with SFF and particularly SOs leads to a slight increase in protection, which depends significantly on the molar ratio of the components. A higher degree of protection is provided by the blends of SOl with SASA. The mixture of 12 mM SOl + 4 mM SASA is the most effective among them. Treatment in such solution with subsequent drying at 65°C significantly slows down corrosion even under severe conditions of periodic condensation of moisture on the specimens. [ABSTRACT FROM AUTHOR]

A fundamental issue in beryllium research is the search for suitable chelating ligands for environmental and biomedical application. In this paper, the speciation of beryllium ions with several multidentate aminopolycarboxylic acids, which are well-known commercial and biomedical chelating agents, has been investigated using electrospray ionisation mass spectrometry (ESI MS). Stoichiometric information, which was readily obtained from the ESI mass spectra, was found to be effective for the preliminary screening of potential encapsulation by tetradentate coordination from a single ligand. Ions observed by ESI MS revealed that the pre-existing solution species and binding affinity trends were preserved into the gas phase in good agreement with previous solution speciation data, suggesting the ability of ESI MS to be developed as a quick, sensitive and safe screening technique to observe beryllium speciation with ligands of interest at low concentrations. The disruption of beryllium-ligand binding by addition of other di- or trivalent metal cations is also reported. [ABSTRACT FROM AUTHOR]

We report the isolation of five new discrete diorganotin di-/mono-carboxylate structures achieved by employing an intramolecular coordination approach. Two diorganotin dicarboxylates, complexes 1 and 2, were obtained from reactions of R2SnCl2 (R = 2-phenylazophenyl) with pyridine-2,6-dicarboxylic acid and pyrazole-3,5-dicarboxylic acid, respectively, in the presence of a base. However, the reactions of R2SnCl2 with 3,4,5-trimethoxybenzoic acid in different stoichiometric ratios in the presence of a base produced two diorganotin monocarboxylates, complexes 3 and 4. An equimolar reaction of R2SnO with 2-(1,8-naphthalimido)ethanoic acid afforded a dinuclear diorganotin carboxylate [R2Sn(μ-OH){C14H8NO4}]2 (5). All the complexes (1–5) are structurally characterized using single-crystal X-ray diffraction analysis. The molecular structures of complexes (1–5) revealed the retention of both N → Sn intramolecular coordinations. Each tin (Sn) center in complexes (1–5) is present in a high coordination number of seven with distorted pentagonal bipyramidal geometry. Time-dependent density functional theory (TDDFT) calculations revealed that ligand-to-ligand transitions dominate electronic transitions in these complexes. The Hirshfeld surfaces and 2D fingerprint plots were analyzed for all the complexes to understand the intermolecular interactions involved in crystal packing. [ABSTRACT FROM AUTHOR]