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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 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 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]

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, 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]

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]

In this paper, zinc aluminate (ZnAlO) nanoparticles were obtained by a new synthesis method, thermal decomposition of Zn(II) and Al(III) carboxylates mixture. Complex combinations were obtained in the redox reaction between Zn(NO)·6HO, Al(NO)·9HO, and 1,3-propanediol at ~130 °C. The mechanism of Zn(II) and Al(III) carboxylates formation and decomposition was observed by thermal analysis and Fourier transform infrared spectroscopy. Zn(II) carboxylate, Al(III) carboxylate, and Zn(II) and Al(III) carboxylates mixture were annealed at different temperatures. Metal oxides synthesized from carboxylates precursors in single metal systems crystallized very well at 400 °C (ZnO) and weak at 800 °C (AlO), as shown by X-ray powder diffractometry. Homogenous mixture of Zn(II) and Al(III) carboxylates heated at 400 °C has led to a mixture of amorphous ZnO and AlO, which reacted forming at 600 °C well-crystallized ZnAlO, with mean crystallites size of 14.2 nm. The decomposition of carboxylates precursors is an appropriate method to obtain ZnAlO spinel as well-crystallized single phase at low temperatures. [ABSTRACT FROM AUTHOR]

Recycling processes for the recovery of metallic content from the electronic wastes are environmentally friendly and economical. This paper reports a method for the recovery and separation of Ni and Co from the sulfate solution by the use of D2EHPA. In this regard, the influence of citrate ion, as a carboxylate ligand, was examined in the separation conditions of Ni and Co via D2EHPA (a poor selective extractant for Ni and Co separation). It was found that the $$ \Delta {\text{pH}}_{0.5}^{\text{Ni-Co}} $$ (the difference between pH values corresponding to 50 pct extraction of metallic ion) increases to 1.5 at the citrate concentration of 0.05 M; this $$ \Delta {\text{pH}}_{0.5}^{\text{Ni-Co}} $$ value is much higher than that obtained in the absence of citrate ion (0.1). Fourier Transform Infrared Spectroscopy (FT-IR) indicated that the citrate ion is co-absorbed during the metallic ions absorption by D2EHPA meaning that the metal-organic complexes contain Co/Ni and citrate ion. Also, the stoichiometric coefficients of the Ni and Co extraction reaction were proposed by applying the slope analysis method. [ABSTRACT FROM AUTHOR]

Gold magnetic nanoparticles (GoldMag) have attracted great attention due to their unique physical and chemical performances combining those of individual FeO and Au nanoparticles. Coating GoldMag with polymers not only increases the stability of the composite particles suspended in buffer but also plays a key role for establishing point-of-care optical tests for clinically relevant biomolecules. In the present paper, poly(4-styrenesulfonic acid-co-maleic acid) (PSS-MA), a negatively charged polyelectrolyte with both sulfonate and carboxylate anionic groups, was used to coat the positively charged GoldMag (30 nm) surface. The PSS-MA-coated GoldMag complex has a stable plasmon resonance adsorption peak at 544 nm. A pair of anti-D-dimer antibodies has been coupled on this GoldMag composite nanoparticle surface, and a target protein, D-dimer was detected, in the range of 0.3-6 μg/mL. The shift of the characteristic peak, caused by the assembly of GoldMag due to the formation of D-dimer-antibody sandwich bridges, allowed the detection. [ABSTRACT FROM AUTHOR]

Carboxylates are ideal directing groups because they are widely available, readily cleavable and excellent linchpins for diverse follow-up reactions. However, their use in meta-selective C−H functionalizations remains a substantial unmet catalytic challenge. Herein, we report the ruthenium-catalyzed meta-C–H alkylation of aromatic carboxylic acids with various functionalized alkyl halides. A bidentate N-ligand increases the electron density at the metal center of ortho-benzoate ruthenacycles to the extent that single-electron reductions of alkyl halides can take place. The subsequent addition of alkyl radicals is exclusively directed to the position para to the CAr–Ru bond, i.e., meta to the carboxylate group. The resulting catalytic meta-C−H alkylation extends to a wide range of (hetero)aromatic carboxylic acids including benzofused five-membered ring heteroarenes but no pyridine derivatives in combination with secondary/tertiary alkyl halides, including fluorinated derivatives. It also allows site-selective C5−H alkylation of 1-naphthoic acids. The products are shown to be synthetic hubs en route to meta-alkylated aryl ketones, nitriles, amides, esters and other functionalized products. Carboxylates are ideal directing groups for aryl C–H functionalizations, given their wide availability and relative ease of functional group interconversion; however, their potential in meta-selective functionalizations has not been fully realized. Here, the authors use carboxylates for meta-selective alkylations via ruthenium catalysis. [ABSTRACT FROM AUTHOR]

A series of 4-ferrcenylbutyl carboxylate esters with different alkyl chain length (C2-C4) of carboxylic acids were synthesized using Fe3O4@SiO2@(CH2)3-Im-bisEthylFc[I] nanoparticles as catalyst and have been characterized with FT-IR, 1H NMR, and 13C NMR. Ferrocenyl-based esters were used as corrosion inhibitors of mild steel in the 1M HCl solution as corrosive media. The corrosion inhibition efficiency of the synthesized ferrocenyl-based esters has been assessed by electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), atomic force microscopy (AFM), and scanning electron microscopy (SEM). The 4-ferrocenylbutyl propionate showed a more effective corrosion inhibition behavior among the studied esters with 96% efficiency after immersion in the corrosive media for 2 weeks. The corrosion inhibition mechanism is dominated by formation of passive layer of inhibitor on the surface of the mild steel by adsorption. Moreover, the adsorption characteristics of 4-butylferrcenyl carboxylate esters on mild steel were thoroughly explored using density functional theory calculations. It was found that the Fe atoms located around the C impurity in the mild steel are the most efficient and active sites to adsorb 4-butylferrcenyl carboxylate esters. [ABSTRACT FROM AUTHOR]

Synthesis and characterization of four new Ni(II) complexes with mixed ligands have been reported in the present paper. As interest ligands, acrylate (acr) ion together with one N-donor heterocyclic ligand, namely benzimidazole (HBzIm), 2-methylbenzimidazole (2-MeBzIm), 5-methylbenzimidazole (5-MeBzIm) or 5,6-dimethylbenzimidazole (5,6-MeBzIm), was chosen. The syntheses afforded the complexes formulated as [Ni(HBzIm)(acr)(HO)]·3HO ( 1), [Ni(2-MeBzIm)(acr)(HO)]·1.5HO ( 2), [Ni(5-MeBzIm)(acr)(HO)] ( 3) and [Ni(5,6-MeBzIm)(acr)] ( 4). Complexes ( 1) and ( 2) contain crystallization water molecules and coordinated water molecules, both their nature and presence being confirmed on the basis of IR spectra and thermal analysis. In contrast to above-mentioned complexes, ( 3) contains only coordinated water molecule, while ( 4) is an anhydrous compound. Based on electronic spectra and magnetic measurements, a distorted octahedral stereochemistry was proposed for all Ni(II) complexes. Acrylate ions act both as unidentate and chelate ligands in complexes ( 1) -( 3), while in complex ( 4) act only as chelate ligands. All used N-donor ligands function as monodentate in all Ni(II) complexes. Biological properties of complexes ( 1) -( 4) were evaluated against several Gram(+), Gram(−) bacterial strains and against fungus Candida albicans. [ABSTRACT FROM AUTHOR]

The present paper analyzes literature data dealing with the use of aminopolycarboxylates for chemical washing of heavy metals contaminated soils. The aim is to rationalize and organize the up-to-date knowledge of process dependence on different parameters, in order to give a contribution to the development of washing protocols applicable for process optimization. Process efficiency is found to be dependent on i) parameters related to soil composition, ii) parameters related to contaminant characteristics and iii) operating parameters. The effect that each of them, according to the reviewed experimental studies, has on process efficiency, is highlighted, and the interdependence among them is presented as a key point to understand the overall removal mechanism and therefore to calibrate its application case-by-case. [ABSTRACT FROM AUTHOR]

[MediaObject not available: see fulltext.] A series of alkyl 2-amino-4-aryl-4 H-chromene-3-carboxylates was synthesized by an efficient, solvent-free one-pot three-component cyclocondensation of resorcinol, aromatic aldehydes, and ethyl or methyl cyanoacetate using sodium carbonate as catalyst. The present methodology offers several advantages, such as a simple procedure with ease of handling, short reaction time, high yields, and the absence of any volatile and hazardous organic solvents. The products were characterized on the basis of IR, H NMR, and C NMR spectral and microanalytical data and evaluated for their antibacterial activity against Gram-positive bacteria ( Staphylococcus epidermidis and Staphylococcus aureus) and Gram-negative bacteria ( Escherichia coli) using paper disc diffusion technique. [ABSTRACT FROM AUTHOR]

This paper presents a recent work on enhanced heat transfer properties of carboxylated water based nanofluids and their corrosive behavior for suitability to automotive conditions. Water mixed with Sebacic acid as carboxylate additive is dispersed with multi-walled carbon nanotubes and tested for corrosion and heat transfer characteristics. Corrosion studies made as per ASTM D 1384 show that carboxylated water dispersed with CNTs is resistant to corrosion and hence suitable for automotive environment. In addition to CNTs, carboxylated water dispersed with nano sized silver, copper and AlO was also tested for corrosion performance but found to be giving considerable corrosion in automotive environment. The stability of CNT based nanofluids in terms of zeta potential is found to be good with carboxylated water compared to deionized water. Significant improvement is observed in the thermal conductivity of nanofluids dispersed with CNTs. The carboxylated water dispersed with very low mass concentration of carbon nano tubes was tested for heat transfer performance in Reynolds number range of 2500 to 6000. The inside overall heat transfer coefficient and overall heat transfer coefficient improved markedly. Also, the velocity of air and flow rate of coolant play an important role in enhancement of the overall heat transfer coefficient. The effect of enhancement of overall heat transfer coefficient on the surface area of heat exchanger and pumping power is found to be significant. [ABSTRACT FROM AUTHOR]

During the examination of two 19th century oil paintings by Swiss artists, the Reading pastor (ca. 1885) by Ferdinand Hodler (1853-1918) and Portrait of a young girl (ca. 1888) by Filippo Franzoni (1857-1911), it was observed that in particular locations, the surface had an unusually granular texture, given by the application of metallic particles and the presence of large translucent green agglomerates. In this paper we investigate the composition and origin of the metal particles and green agglomerates. A combination of bulk analysis (GC-MS and FTIR) and analytical microscopy techniques (X-ray tomographic microscopy, light microscopy, ATR-FTIR-FPA imaging and SEM-EDX) were used. It was concluded that the metal particles are composed of a lower quality brass (copper/zinc alloy) and ground from foil. The current appearance resulted from the reaction of the brass and its corrosion products with the fatty acids in the surrounding paint/varnish matrix. This has lead to the formation of agglomerates of zinc and copper carboxylates, the latter responsible for their green colour. [ABSTRACT FROM AUTHOR]

Poor light absorption ability severely limit the photocatalytic efficiency of metal–organic frameworks (MOFs) for chemical transformations. Herein, we have integrated the zinc(terpyridine) complex as "molecular antennas" into backbone of MOFs, to harvest visible light for aerobic oxidative coupling of amines. Two photoactive MOFs of Zn-CTP [CTP = (4′-(4-carboxyl)-terpyridine] and Zn-TPBA {TPBA = 4-([2,2′:6′,2′′-terpyridin]-4'-yl)benzoic acid} were thus prepared by employing the terpyridine-containing aromatic carboxylate ligands of CTP and TPBA as the organic linkers, respectively, to coordinate with zinc nitrate under solvothermal condition. Characterization results suggested the successful chelation of terpyridine with zinc(II) ions, giving zinc(terpyridine)-containing MOFs with high crystallinity. The incorporated zinc(terpyridine) complexes indeed acted as the "molecular antennas" in MOF to harvest visible light. Furthermore, π-conjugated terpyridine in organic linkers favored the charge transfer, leading to efficient charge separation in MOFs. Both zinc(terpyridine)-containing MOFs thus demonstrated high activities in the visible light-driven oxidation of amines to imines in air at room temperature. Particularly, extended π-conjugated linker of TPBA could further enhance the delocalization of conjugated electrons and optimize the electronic band structure that in favour of photocatalytic activity. As a result, Zn-TPBA enables almost quantitative oxidative coupling of benzylamine under visible light irradiation in atmospheric air, which was even more efficient than other reported photocatalysts in pure oxygen atmosphere. The salient advantages, such as operational simplicity, environmentally friendly, energy efficient, and high efficiency, made such photocatalytic system highly promising and practical in industrial application. Zinc(terpyridine) complex acted as "light antennas" in MOFs, making oxidative coupling of amines highly efficient under visible light in air. [ABSTRACT FROM AUTHOR]

Synthesis of two homoleptic and five heteroleptic zinc (II) carboxylate complexes with two different ligands: HL1 = 3-chlorobenzoic acid and HL2 = 2-(4-chlorophenyl) acetic acid have been reported in this paper. The general formulae of the two homoleptic complexes are: Zn(L1)2(1), and Zn(L2)2(2). Similarly, the general formulae for two different types of heteroleptic complexes are: (Type-I): [(Zn)2(L1)4(bipy)2(H2O)] (3), [Zn(L2)2(bipy)(H2O)] (4) and (Type-II): [ZnL1L2] (5), [ZnL1L2(py)] (6) and [ZnL1L2(bipy)] (7). The synthesized complexes were characterized in the solid state by FT-IR, CHN analyses and in solution state by NMR (1H, 13C) spectroscopy. Complexes 3 and 4 were also characterized by single crystal analysis where data revealed that the geometry around each Zn atom is distorted trigonal bipyramidal and octahedral, respectively. The synthesized complexes were interacted with SS-DNA and CTAB (surfactant). Interaction of the synthesized compounds with SS-DNA was studied by UV–visible spectroscopy and viscometry and intercalative mode of interaction was exhibited. Moreover, the interaction of the synthesized complexes with CTAB was studied by conductometry showing a strong binding that is evident from higher CMC and negative Gibbs free energy of micellization (ΔGm) values. The tested compounds were further screened for in vitro antibacterial and antifungal activities and were found active against the studied strains of bacteria and fungus. [ABSTRACT FROM AUTHOR]

Two metal-organic frameworks based on Cd(II) and 2-iodo-(2-I-Bdc) and 2,5-diodo-(2,5-I-Bdc)terephthalate were obtained: {[Cd(2-I-Bdc)(Bbi)]} (I) and {[Cd2(2,5-I-Bdc)2(DMF)2(Bbi)]} (II) (Bbi = 1,1'-(1,4-butanediyl)bis(imidazole)). The structures of both complexes were established by X-ray diffraction (CCDC no. 2258217 (I) and 2257566 (II)). [ABSTRACT FROM AUTHOR]

The review addresses the main approaches to desulfurization of hydrocarbon products by adsorption methods. Examples of the use of various supports (metal-organic frameworks, various porous carbons, silica, and alumina) for the removal of acidic sulfur components from gas and liquid hydrocarbons are presented. Modification of the supports with transition metals, oxides, salts, and complex compounds to remove hydrogen sulfide and thiols from hydrocarbon raw materials is substantiated. The environmental friendliness and lower energy consumption for the use of silica gel modified with Zn(II), Co(II), Ni(II), and Cu(II) carboxylates to refine hydrocarbon fuel are demonstrated. A comparison of the theoretical calculations (DFT) with experimental results attests to good agreement between the data. The choice of the parameters for silica gel surface modification with metal carboxylates is discussed, including pore size of the support, time and power of the ultrasonic treatment for the support impregnation with solutions of complexes, optimal concentration of transition metal complexes, effect of the geometry of complexes on their adsorption and on the absorption of acidic sulfur components, and so on. According to quantum chemical calculations and experimental results, metal sulfides are formed as the final products of reactions of both hydrogen sulfide and thiols with metal carboxylates. Zinc pivalate is proposed as the most promising modifier for silica, which not only efficiently removes sulfur impurities, but also gives rise to nontoxic zinc sulfide supported on silica gel. [ABSTRACT FROM AUTHOR]

The reactivities of various fatty monoacids and diacids on copper metal-containing surfaces were investigated through reflection–absorption infrared spectroscopy. The formation of copper carboxylates is detected on pure copper surfaces, while copper and zinc carboxylates are simultaneously formed on brass surfaces. Following the decrease of acid carbonyl and the formation of carboxylate infrared bands, it is shown that fatty monoacids C8 and C10 react with clean/polished copper and its zinc alloy within 2–4 h, while those with chains > C12 react within days. At the end of the processes, only the corresponding metal carboxylates are detected in all cases. An explanation for the above is offered on a molecular mobility and acidity basis, where the lower monoacids (liquids in room temperature), also having lower pKa values, favor higher reaction rates. Furthermore, it is argued that longer-chain fatty monoacids, when deposited from their solutions, allow for favorable orientation resulting in self-assembled monolayer-type molecular packing on the copper surface, which may additionally rationalize the slower reaction. Interestingly, fatty diacids do not form any carboxylate products under the same conditions, as it is argued that their molecules may efficiently pack as self-assembled multilayers on copper and ultimately protect it. The possible implications of the fatty monoacid and diacid behavior on the archaeological organic residues level and regarding the stability of copper alloys are discussed. [ABSTRACT FROM AUTHOR]

We report the synthesis and structural, spectroscopic and magnetic properties of new 1D coordination polymeric complex {[Cu(μ-l-Arg)2]SO4⋅1.5H2O}n (1) that contains asymmetric μ−O,O' carboxylic bridge linking distorted square-pyramidal [Cu(μ-l-Arg)2]2+ coordination units. In 1D, the syn−anti−μ2−η1:η1zigzag polymer conformation, the adjacent Cu(II) ions are distanced by 5.707 Å, and the subsequent Cu∙∙∙Cu proximity in 1D-coordination chain equals 6.978 Å. Detailed interpretation of IR and Raman spectra of l-arginine and 1 was performed. The principal components of the g tensor determined from EPR experiments (gx = 2.059, gy = 2.075, gz = 2.228) indicate nearly axial symmetry of Cu(II) coordination sphere and correspond to the unpaired electron occupying the dx2–y2 orbital. The single broad band at 16,200 cm–1, characteristic of d−d transition, is assigned to the dominant dublet-dublet 2B1g(dx2–y2)→ 2Eg(dyz≈dxz) transition. Magnetic susceptibility measurements have revealed ferromagnetic coupling between the Cu(II) ions within the 1D-coordination chain, while the intermolecular coupling is antiferromagnetic. [ABSTRACT FROM AUTHOR]

The reaction of cobalt pivalate [Co(Piv)2]n and in situ generated N‑heterocyclic carbene IPrPh (1,3-bis(2,6-diisopropylphenyl)-2-phenylimidazol-4-ylidene) affords heteroligand complexes [Co2(Piv)4-(IPrPh)2] (I), [Co2(Piv)2.8(OtBu)1.2(IPrPh)2] (II), and [Co3(μ3-O)(Piv)4(IPrPh)2] (III). The structures of complexes II·C6H14 and III are determined by X-ray diffraction (XRD) (CIF files CCDC nos. 2216724 and 2216725, respectively). Exchange spin-spin interactions between the magnetic Со2+ ions in the synthesized compounds are estimated by quantum chemical calculations. [ABSTRACT FROM AUTHOR]

Nisin is a natural bacteriocin that exhibits good antibacterial activity against Gram-positive bacteria. It has good solubility, stability, and activity under acidic conditions, but it becomes less soluble, stable, and active when the solution pH exceeds 6.0, which severely restricted the industrial application range of nisin as antibacterial agent. In this study, we investigated the potential of complexing nisin with a cyclodextrin carboxylate, succinic acid-β-cyclodextrin (SACD), to overcome the disadvantages. Strong hydrogen bonding was shown between the nisin and SACD, promoting the formation of nisin-SACD complexes. These complexes exhibited good solubility under neutral and alkaline conditions, and good stability after being held at high pH values during processing with high-steam sterilization. Moreover, the nisin-SACD complexes displayed significantly improved antibacterial activity against model Gram-positive bacteria (S. aureus). This study shows that complexation can improve the efficacy of nisin under neutral and alkaline situations, which may greatly broaden its application range in food, medical, and other industries. [ABSTRACT FROM AUTHOR]

An oxalate-degrading bacterium in the gut microbiota absorbs food-derived oxalate to use this as a carbon and energy source, thereby reducing the risk of kidney stone formation in host animals. The bacterial oxalate transporter OxlT selectively uptakes oxalate from the gut to bacterial cells with a strict discrimination from other nutrient carboxylates. Here, we present crystal structures of oxalate-bound and ligand-free OxlT in two distinct conformations, occluded and outward-facing states. The ligand-binding pocket contains basic residues that form salt bridges with oxalate while preventing the conformational switch to the occluded state without an acidic substrate. The occluded pocket can accommodate oxalate but not larger dicarboxylates, such as metabolic intermediates. The permeation pathways from the pocket are completely blocked by extensive interdomain interactions, which can be opened solely by a flip of a single side chain neighbouring the substrate. This study shows the structural basis underlying metabolic interactions enabling favourable symbiosis. In our gut, oxalate-degrading bacteria absorb oxalate, a causative substance for kidney stone formation, and reduce our health risk. In this work, the authors report the structure of the oxalate transporter responsible for this process and how the protein works. [ABSTRACT FROM AUTHOR]

Purpose: Root exudation of organic acids (OAs) facilitates plant P uptake from soil, playing a key role in rhizosphere nutrient availability. However, OA exudation responses to CO2 concentrations and water availability remain largely untested. Methods: We examined the effects of CO2 and water on OA exudates in three Australian woodland species: Eucalyptus tereticornis, Hakea sericea and Microlaena stipoides. Seedlings were grown in a glasshouse in low P soil, exposed to CO2 (400 ppm [aCO2] or 540 ppm [eCO2]) and water treatments (100% water holding capacity [high-watered] or 25–50% water holding capacity [low-watered]). After six weeks, we collected OAs from rhizosphere soil (OArhizo) and trap solutions in which washed roots were immersed (OAexuded). Results: For E. tereticornis, the treatments changed OArhizo composition, driven by increased malic acid in plants exposed to eCO2 and increased oxalic acid in low-watered plants. For H. sericea, low-watered plants had higher OAexuded per plant (+ 116%) and lower OArhizo per unit root mass (–77%) associated with larger root mass but fewer cluster roots. For M. stipoides, eCO2 increased OAexuded per plant (+ 107%) and per unit root mass (+ 160%), while low-watered plants had higher citric and lower malic acids for OArhizo and OAexuded: changes in OA amounts and composition driven by malic acid were positively associated with soil P availability under eCO2. Conclusion: We conclude that eCO2 and altered water availability shifted OAs in root exudates, modifying plant–soil interactions and the associated carbon and nutrient economy. [ABSTRACT FROM AUTHOR]

Crystals of Sodium Laurate, Lauric Acid (NaLLA) were obtained and the structure was determined by single-crystal X-ray diffraction. The new crystal form is monoclinic of space group P21/c. The asymmetric unit contains two independent laurate molecules whose carboxylic/carboxylate groups are linked by a low barrier O-H...O hydrogen bond. Two lauric/laurate molecules are in a head-to-head configuration and the elongated hydrophobic chains are parallel to the long b axis. The carboxylic hydrogen atom was found to be disordered, bound on each of the two carboxylate groups in an unsymmetrical way. The non-symmetrical character of the hydrogen bond is related to the presence of two independent fatty acid molecules in the asymmetric unit and is in accordance with the different lengths of the four C-O bonds present in the molecular structure. The crystal structure was analyzed in terms of interactions on the Hirshfeld surface. The packing is stabilized by hydrogen bonds and O...Na ionic interactions in the hydrophilic layer and by C-H...H-C contacts in the hydrophobic layers which are the most enriched major contacts. [ABSTRACT FROM AUTHOR]

New complex compounds[(2-clpy)2Pd(OOCMe)2] (I), [{(Ph)Pd(2-clpy)}2(OOCMe)4Pd]·3C6H6 (II), and [{(Ph)Pd(2-clpy)}2(OOCMe)4Pd] (III) are obtained in the interaction of palladium acetate [Pd3(OOCMe)6] with 2-chloropyridine (2-clpy) and structurally characterized by single crystal X-ray diffraction. It is found that in the inert medium, mononuclear compound I forms and it can be isolated in the crystalline state, while trinuclear complexes II and III are the products of benzene metalation with palladium under mild conditions. [ABSTRACT FROM AUTHOR]

Research reported by Liu et al. in this issue shows that hyperaccumulation of rare earth elements (REEs) in Phytolacca americana occurs because its roots release carboxylates and lower the pH of the rhizosphere. The main function of carboxylate release in this species appears to be enhanced uptake of phosphorus (P). The idea that REE hyperaccumulation may have arisen as a side-effect of P acquisition is an example of the "inadvertent uptake" hypothesis for hyperaccumulation. In this Commentary, I consider the extent to which similar processes may be widely important among all hyperaccumulators. There are some relatively unspecialized hyperaccumulator species, like P. americana, which accumulate multiple elements and grow on a wide range of soils, most of which are not unusually enriched in any elements. It may be that carboxylate release explains the physiological functioning of these plants, at least in part. However, most hyperaccumulators are more specialized, accumulating specific elements and occurring exclusively on metalliferous soils. In such species, current evidence suggests that hyperaccumulation is more dependent on the plants' internal mechanisms of elemental transport, sequestration, and detoxification than on rhizosphere processes. Nonetheless, inadvertent uptake as a consequence of P- acquisition mechanisms may have been an important starting point in the evolution of such lineages. [ABSTRACT FROM AUTHOR]

The review deals with the topology of homonuclear carboxylate complexes of cobalt(II, III) and cobalt(III) whose structures are built from the monocarboxylate anions RCOO (R is a radical containing no electron-donating substituents), water, and its deprotonated forms. [ABSTRACT FROM AUTHOR]

In this title compounds 3-ethyl 1,2-dimethyl 5-chloroindolizine-1,2,3-tricarboxylate 3 and 3-ethyl 1,2-dimethyl 5-bromoindolizine-1,2,3-tricarboxylate 4, there are two molecules in the asymmetric unit. This crystal was prepared by one-pot multicomponent reaction of 2-chloro-1-(2-ethoxy-2-oxoethyl)pyridin-1-ium bromide salt 1 with dimethyl acetylenedicarboxylate 2 in the presence triethylphosphite at room temperature in high yield. The indolozine products were confirmed with IR, mass, H, and C NMR. X-ray crystallographic technique was also conducted and the result showed the crystal belong to monoclinic system, space group pbca with a = 17.6696(7), b = 7.9336(3), c = 23.2275(9)Å, v = 3093.1(2)Å, D = 1.521 mg/m, µ = 0.31 mm. In both compounds no typical hydrogen bonding interactions could be located. Graphical Abstract: Synthesis, and crystal structure of two 3-ethyl 1,2-dimethyl 5-chloroindolizine-1,2,3-tricarboxylate and 3-ethyl 1,2-dimethyl 5-bromoindolizine-1,2,3-tricarboxylate are reported. [ABSTRACT FROM AUTHOR]

A novel electrochemiluminescence (ECL) aptasensor for the determination of lincomycin (LIN) was developed based on CdS QDs/carboxylated g-C3N4 (CdS QDs/C-g-C3N4). CdS QDs/C-g-C3N4 served as the substrate of the aptasensor, and then CdS QDs/C-g-C3N4-modified electrode was incubated with aptamer DNA (Apt-DNA). When the non-specific sites of the electrode surface was blocked by 6-mercaptohexanol, the ferrocene-labeled probe (Fer-DNA) was assembled onto the electrode surface through base complementation with Apt-DNA. In the absence of LIN, the ECL signal was quenched effectively by Fer-DNA and a decreased ECL emission (off state) was acquired. On the contrary, LIN was specifically bond with Apt-DNA, and Fer-DNA was detached from the aptasensor surface because of the deformation of Apt-DNA, resulting in an effectively enhanced ECL signal (on state). The constructed ECL aptasensor exhibited a wide detection range for LIN determination (0.05 ng mL−1–100 μg mL−1) with a low detection limit (0.02 ng mL−1). Importantly, the proposed ECL aptasensor showed outstanding accuracy and specificity for LIN determination, and also provided a potential strategy for other antibiotic determinations. [ABSTRACT FROM AUTHOR]

Two new heterometallic structures of [Zn2Ba(TCA)2(H2O)2]·2n(H2O) (1) and [Cd2Ba(TCA)2(DMA)2(H2O)3]·2n(DMA) (2) were successfully prepared via the solvothermal reactions of 4,4ʹ,4″-ticarboxytriphenylamine (H3TCA) with Zn(NO3)2·6H2O salts and Ba(NO3)2 or Cd(NO3)2·4H2O salts and Ba(NO3)2. The structural characterization results show that complex 1 features a 3D framework structure based on the 1D rod-like heterometal-carboxylate chains while the 3D framework of 2 is constructed from the trinuclear [Cd2Ba(COO)4] cluster. Due to the triphenylamine chromophore of TCA3−, compounds 1–2 show intensive luminescence at room temperature. Their application values on the ICU infection treatment were explored, and we also discussed the corresponding mechanism simultaneously. The utilization of enzyme linked immunosorbent assay detection was done firstly and then content of inflammatory cytokines released into the plasma was determined. Then, the measurement of Toll-like receptor 4 activation was made by real time reverse transcription-polymerase chain reaction. The CCK-8 assay was conducted in this study to evaluate the toxicity of the new compound during treatment. [ABSTRACT FROM AUTHOR]

Chemists are pretty much acquainted with coordination compounds bearing carboxylate moieties. Nevertheless comprehensive literature on the subject correlating activity and toxicity with varied organotin(IV) carboxylates containing a diverse array of ligand moieties under identical experimental parameters is lacking. In view of the exciting structural and biological importance attributed to organotin(IV) compounds, the current research work involved synthesizing di- and triorganotin(IV) analogues of carboxylate ligand with hexyl aliphatic, aromatic and alicyclic backbone. The new organotin(IV) complexes with cyclohexane carboxylic acid (L1), benzoic acid (L2), and heptanoic acid (L3) were synthesized by the reaction of di- and triorganotin(IV) salts in the presence of trimethylamine as base. The coordination mode of ligand, structural confirmation and geometry assignment of complexes were established using FT-IR, 1H NMR and 13C NMR spectra. The IR data implied that in both di- and triorganotin(IV) carboxylates, the ligand moiety—(COO) acted as a bidentate group in solid state. 1H and 13C NMR data revealed that tri and diorganotin(IV) complexes occurred as monomeric entities with tetrahedral geometry around tin in solution. The synthesized complexes were also evaluated for their antibacterial and antifungal activity. The results showed that synthesized complexes have greater inhibition potential against different strains of bacteria and fungi compared with the corresponding free ligands. Triorganotin(IV) compounds were found to be more potent against tested bacterial and fungal strains than that of diorganotin(IV) derivatives, having moderate antioxidant activity. Most of the organotin(IV) complexes of benzoic acid were found to be more potent against strains of bacteria and fungi than that of corresponding complexes of other ligands showing that for a biological activity to be shown by a complex, the role of ligand was crucial. [ABSTRACT FROM AUTHOR]

Direct implementation of metal-organic frameworks as the catalyst for CO2 electroreduction has been challenging due to issues such as poor conductivity, stability, and limited > 2e− products. In this study, Au nanoneedles are impregnated into a cupric porphyrin-based metal-organic framework by exploiting ligand carboxylates as the Au3+ -reducing agent, simultaneously cleaving the ligand-node linkage. Surprisingly, despite the lack of a coherent structure, the Au-inserted framework affords a superb ethylene selectivity up to 52.5% in Faradaic efficiency, ranking among the best for metal-organic frameworks reported in the literature. Through operando X-ray, infrared spectroscopies and density functional theory calculations, the enhanced ethylene selectivity is attributed to Au-activated nitrogen motifs in coordination with the Cu centers for C-C coupling at the metalloporphyrin sites. Furthermore, the Au-inserted catalyst demonstrates both improved structural and catalytic stability, ascribed to the altered charge conduction path that bypasses the incoherent framework. This study underlines the modulation of reticular metalloporphyrin structure by metal impregnation for steering the CO2 reduction reaction pathway. Metal-organic frameworks are promising catalysts for CO2 electroreduction, yet limited by their poor conductivity and stability. Here, Au nanoneedles are inserted into the metalloporphyrin framework to activate C-C coupling and stabilize the structure for much enhanced ethylene production. [ABSTRACT FROM AUTHOR]

Three new bioactive nanosized supramolecular cobalt coordination polymers; {[Co2(tyr)2(Morph)2(Cl)2(H2O)2]}n (1), {[Co(Morph)6]+2[Co(bdc)(Morph)2(Cl)2]−2.3H2O}n (2) and {[Co(Morph)6]+2[Co(H2btec)(Morph)3(H2O)]−2.10H2O}n (3), where L-tyr = L-tyrosine, H2bdc = Terephthalic acid, H4btec = Pyromellitic acid and Morph = Morphline, they were prepared and characterized by elemental analysis, FT-IR and UV–VIS spectroscopies, magnetic, molar conductance, TGA/DTA, XRPD, catalytst and MM2 theoretical calculations. In all three compounds, the Morph ligand adopts a bidentate chelating coordination mode and the carboxylate anions of bdc−2 and H2btec−2 act as monodentate ligands while the tyr−1 anion act as bidentate ligand. The coordination geometry of the cobalt centers is an octahedral. The variation of carboxylates, morphline and central cobalt ions exerts a significant effect on the structures, properties and biological activity. Kinetic and thermodynamic parameters (n, E*, Z, ΔH*, ΔS* and ΔG*) were computed using Coats–Redfern equations and discussed, which confirms the second order kinetics. From the XRPD patterns, the crystal parameters as well as the particle sizes of the complexes could be evaluated. Complexes exhibit catalytic activity. The biological activity of the compounds has also been study against different bacteria and fungi. [ABSTRACT FROM AUTHOR]

Force-field parameters are required for classical molecular dynamics (MD) simulations. Generally, these force fields are well described for organic molecules but are missing for transition metal complexes, especially those with heavy metals. In the present study, the structure and force constants of important carboxylate Pt(II)-complexes were obtained from a systematic benchmarking including 70 quantum mechanics computational protocols. The best protocol was selected based on the structure and vibrational spectrum for carboplatin, namely LC-ωPBE/LANL2TZ(f)/6-31+G(2df)/IEF-PCM(UFF). The resulting force field was used for MD simulation of carboplatin, oxaliplatin and nedaplatin in an aqueous solution. The MD trajectories were analyzed and discussed regarding the solute structure and solute–solvent interaction. For carboplatin, some solute–solvent clusters with 2–16 water molecules were selected and used to calculate the Pt-195 NMR chemical shift. The results clearly show the primary role of the explicit solute–solvent interaction on the Pt-195 chemical shift, with the agreement with the experiment being improved systematically with the inclusion of water molecules up to 16, which error was only 20 ppm (1.1%). Overall, the force-field parameters for carboxylate Pt(II)-complexes provided here are very useful to study the interaction of these molecules with proteins, DNA, etc., using classical MD simulations. [ABSTRACT FROM AUTHOR]

Path-Integral Molecular Dynamics (PIMD) method is key to include nuclear quantum effects (NQEs) in molecular dynamics simulations which can influence a variety of properties. As a first application of the interface between the i-PI code and the deMon2k electronic structure code, we apply it to evaluate NQEs on the 13 C isotropic nuclear shielding/chemical shift of a set of linear carboxylate ions solvated by a water cluster. A quantum mechanics / molecular mechanics treatment of the electronic structure in conjunction with relevant combination of thermostat and number of replicas in the PIMD algorithm allows for a good convergence of the 13 C isotropic nuclear shielding values regardless of the considered carboxylate. The simulations demonstrate that regardless of the considered carboxylate ion and carbon atom, inclusion of NQEs always improves agreement with the experimental data when looking at relative 13 C isotropic chemical shifts in a given compound. The present study thus paves the ways to new applications of the deMon2k code, whether it be for pure quantum mechanics or quantum mechanics / molecular mechanics simulations, for simulations taking into account NQEs. [ABSTRACT FROM AUTHOR]

A new binuclear copper(II) complex Cu2(Piv)4(L)2, where Piv– = pivalate, L = 2,6-di-tert-butyl-4-(3,5-bis(4-pyridyl)pyridyl)phenol, was synthesized, and its molecular and crysral structures were determined at temperatures of 160, 173, and 296 K (CIF files CCDC no. 2144104, 2144105, and 2144106, respectively). Cyclic voltammetry measurements revealed three irreversible oxidation processes in the potential range of 0.5–1.2 V versus Fc+/Fc. Analysis of the temperature dependence of the magnetic susceptibility of Cu2(Piv)4(L)2 showed that antiferromagnetic interactions of Cu2+ ions predominate in the complex. It was found that the oxidation of Cu2(Piv)4(L)2 upon grinding with PbO2 or treatment of a solid sample with an aqueous solution of K3[Fe(CN)6] affords long-lived phenoxyl radical, which can be detected by ESR spectroscopy. [ABSTRACT FROM AUTHOR]

Cellulose-derived films have received attention for possible use in the packaging industry. However, the poor mechanical properties of the biofilm are the main concern. This study aims to mildly carboxymethylate cellulose fibers and esterify the generated carboxymethylated cellulose fibers (CMF) for film production. The physicochemical alteration of cellulose fibers via carboxymethylation and esterification was confirmed by means of solid-state carbon NMR, FTIR, and XPS analyses. The carboxymethylation of cellulose fibers impacted their surface morphology and fiber length dramatically. The results confirmed that the carboxymethylated cellulose fibers (CMF) with a 1.2 mmol/g carboxylate group generated films with the highest mechanical properties. The higher degree of carboxymethylation tended to reduce the mechanical properties but improved the optical properties of the CMF film as smaller CMF could scatter light more effectively. The use of acetic acid (3 wt%) was crucial in the esterification of CMF to generate CMF film with the highest tensile strength (60.8 MPa), but a higher concentration of acetic acid would impair the mechanical properties of the film. The great tensile strength of the CMF derived film (60.8 MPa) and the relatively uncomplicated fabrication procedure of CMF films are promising for some applications, such as bags and agriculture uses. However, the water uptake of the CMF films was relatively high (3–4 g/g), and further research needs to address this challenge. [ABSTRACT FROM AUTHOR]

The Na+-dependent dicarboxylate transporter from Vibrio cholerae (VcINDY) is a prototype for the divalent anion sodium symporter (DASS) family. While the utilization of an electrochemical Na+ gradient to power substrate transport is well established for VcINDY, the structural basis of this coupling between sodium and substrate binding is not currently understood. Here, using a combination of cryo-EM structure determination, succinate binding and site-directed cysteine alkylation assays, we demonstrate that the VcINDY protein couples sodium- and substrate-binding via a previously unseen cooperative mechanism by conformational selection. In the absence of sodium, substrate binding is abolished, with the succinate binding regions exhibiting increased flexibility, including HPinb, TM10b and the substrate clamshell motifs. Upon sodium binding, these regions become structurally ordered and create a proper binding site for the substrate. Taken together, these results provide strong evidence that VcINDY's conformational selection mechanism is a result of the sodium-dependent formation of the substrate binding site. DASS carboxylate transporters linked to metabolic diseases couple the Na+ gradient to nutrient uptake. Here, the authors unravel the structural basis by which Na+ binding coordinates substrate interactions, revealing a distinct coupling mechanism. [ABSTRACT FROM AUTHOR]

Two new metal-organic frameworks of composition [Eu2(phen)2Cl2(chdc)2] • 1.1DMF• •0.7diox (1•1.1DMF•0.7diox, phen is 1,10-phenanthroline, DMF is N,N-dimethyl-formamide, diox is dioxane) and [Tb2(phen)2Cl2(chdc)2] • 2diox • 2H2O (2 • 2diox • 2H2O) were synthesized using the conformationally flexible alicyclic ligand, trans-1,4-cyclohexane-dicarboxylic acid (H2chdc). The mononuclear complex [Tb(phen)2(DEF)(H2O)Cl2]Cl (3, DEF is N,N-diethylformamide) was also prepared. The structures of the reaction products were determined by single-crystal X-ray diffraction. The compositions and nature of the compounds 1 • 0.6DMF• 2.5H2O and 2 • 0.5diox • 4H2O, which were obtained after the separation of single crystals from the mother liquor, were confirmed by IR spectroscopy, elemental analysis, and thermogravimetric analysis. Both these compounds are composed of the binuclear units {Ln2(phen)2Cl2(O2CR)4} and are rare examples of the coordination of a halide anion to the LnIII ion in the metal-organic framework. The three-dimensional packing of the layers in the structures of 1 and 2 contains voids with a total volume of 35 and 32%, respectively. [ABSTRACT FROM AUTHOR]

The ethyl 2-[2-(2-nitrobenzylidene)hydrazinyl]thiazole-4-carboxylate (1), a thiazole ester, was synthesized by refluxing 1-(2-nitrobenzylidene)thiosemicarbazide and ethyl bromopyruvate. The compound is characterized by spectrometric, spectroscopic and single crystal (SC-XRD) techniques. Non-covalent interactions that are responsible for crystal packing are explored by Hirshfeld surface analysis. All theoretical calculations were performed by DFT quantum chemical methods using 6-311G(d,p) and cc-pVTZ basis sets and compared. Theoretical harmonic frequencies of ethyl 2-[2-(2-nitrobenzylidene)hydrazinyl]thiazole-4-carboxylate (1) were optimized. Confirmation of hydrogen bonding sites was analyzed by molecular electrostatic potential (MEP) and Mulliken population analysis. The vibrational frequencies of characteristic functional groups and chemical shifts were found in good agreement with experimental assignments. Frontier molecular orbital (FMO) revealed relatively small HOMO–LUMO (highest occupied molecular orbital-lowest unoccupied molecular orbital) gape, which speaks off the nearly planar geometry and extended conjugation, as compared to the substituents with no conjugation possible. It has also been observed that –NO2 substituent plays a vital role for this relatively small HOMO–LUMO gape and overall electronic properties when compared with similar thiazole carboxylates (2–6, Table 6). Ethyl 2-[2-(2-nitrobenzylidene)hydrazinyl]thiazole-4-carboxylate (1) was also evaluated for its anti-oxidant and anti-microbial activities. [ABSTRACT FROM AUTHOR]

Choline-based ionic liquids, involving various alkyl chains lengths and carboxylates derived from biobased acids, have been synthetized with high yields through a three step procedure. These biobased ionic liquids showed excellent solubilisation properties for cellulose and lignin under mild conditions. Cellulose could be dissolved up to 32.5% and lignin up to 65.4% without transformation towards amorphous state. Comparison with commercial ionic liquids or commonly used ones has been also realized and discussed. The good dissolution of these two biopolymers in biobased ionic liquids will allow the design of new biomaterials from cellulose or lignin and the isolation of many molecules presenting interest in the chemical industry. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate anaerobic digestion of wheatgrass in the absence of hydrolytic pre-treatments. The effect of solids retention time (SRT) (1–64 days), inoculum acclimation (0–80 days acclimation), temperature (40–70 °C) and buffer capacity (20–200 mM phosphate buffer) on conversion of the feedstock, yield and composition of liquid-phase products (ethanol and short-chain organic acids, SCOAs) and COD removal was investigated in semi-continuous (intermittent feed) completely mixed reactors. SRT had the most important effect on process performance. Biodegradation of the feedstock was favoured at high SRT, with 61% removal of volatile suspended solids and 84% removal of total carbohydrates at SRT 64 days. However, low yield of liquid-phase products was observed at high SRT because of strong methanogenic activity (57% removal of the total COD). The highest yield of liquid-phase products was 20% (COD basis) at SRT 8 days. Although high biodegradation of the feedstock was observed after long-term batch acclimation (30 and 80 days), once the digestion conditions were switched to semi-continuous at short SRT (2 days), the biodegradation of the feedstock decreased considerably. The best process performance was observed at 40 °C. [ABSTRACT FROM AUTHOR]

In a quest to discover new formulations for the treatment of various parasitic diseases, a series of heteroleptic triorganobismuth(V) biscarboxylates of type [BiR3(O2CR′)2], where R=C6H5 for 1–4 and p-CH3C6H4 for 5–8, were synthesized, characterized and evaluated for their biological potential against L. tropica. All the synthesized complexes were fully characterized by elemental analysis, FT-IR, multinuclear (1H and 13C) NMR spectroscopy and X-ray crystallography. The crystal structures for [BiPh3(O2CC6H4(o-Br))2] (1), [BiPh3(O2CC2H2C6H4)2] (2), [BiPh3(O2CC6H4(m-NO2))2] (3) and [BiPh3(O2CC6H4(2-OH,3-CH3))2] (4) were determined and found to have a distorted pentagonal bipyramidal molecular geometry with seven coordinated bismuth center for 1–3 and for 4 distorted octahedral geometry, respectively. All the synthesized complexes demonstrated a moderate to significant activity against leishmania parasites. A broad analytical approach was followed to testify the stability for (1–8) in solid state as well as in solution and in leishmanial culture M199, ensuring them to be stable enough to exert a significant antileishmanial effect with promising results. Cytotoxicity profile suggests that tris(tolyl) derivatives show lower toxicity against isolated lymphocytes with higher antileishmanial potential. Molecular docking studies were carried out to reveal the binding modes for (1–8) targeting the active site of trypanothione reductase (TR) (PDB ID: 4APN) and Trypanothione Synthetase-Amidase structure (PDB ID 2vob). [ABSTRACT FROM AUTHOR]

Two new metal–organic coordination complexes, {[Cd8(tdc)8(bbi)8(H2O)8]·4DMF]}n (1) and {[Cd(cbba)2(m-bix)2]}n (2) (H2tdc = 2,5-thiophenedicarboxylic acid, bbi = 1,1′-(1,4-butanediyl)bis (imidazole), Hcbba = 2-(4-chlorobenzoyl)benzoic acid, m-bix = 1,3-bis((1H-imidazolyl)-methyl) benzene) were synthesized under hydrothermal conditions and characterized by techniques of single-crystal X-ray diffraction analysis, elemental analysis, powder X-ray diffraction and thermogravimetric analysis (TGA). Single-crystal structure analyses reveal that complex 1 displays a 3D 4-connected threefold interpenetrating framework with the point symbol of {42·84}. Complex 2 shows a 3D supramolecular architecture via intermolecular hydrogen bonds and intermolecular π⋯π stacking interactions. Furthermore, the luminescence of the two complexes was also studied. [ABSTRACT FROM AUTHOR]

On the basis of 1,3,5-tris(2-methylimidazol-1-yl)benzene (timb) ligand, a designed tripodal connector, a new coordination polymer (CP) containing Cu(II) ions as nodes has been generated by reaction between timb ligand and Cu(NO3)2·3H2O in the presence of the second carboxylate ligand 5-Br-isophthalic acid (Br-H2IPA), and its chemical formula is {[Cu4(timb)2(Br–IPA)4]·5H2O}n (1). Furthermore, due to its excellent framework stability in water, complex 1 possesses high photocatalytic effects for the methylene blue (MB) degradation under the irradiation of UV light, and its process of photodegradation is chiefly resulted from the radical ·OH radicals. Its application values on the hypertension were assessed, simultaneously, its detailed mechanism could be investigated. The blood pressure meter was used in this research to evaluate the blood pressure of the animals. The real time reverse transcription-polymerase chain reaction (RT-PCR) was accomplished and the Vitamin D (VitD) receptor expression levels against the vascular endothelial cells. Molecular docking simulation demonstrated that both imidazole and carboxyl groups were found to be active to the active sites from target protein Vitamin D. [ABSTRACT FROM AUTHOR]

Using the reactions of copper(II) acetate magnesium(II) oxide with 2-furancarboxylic acid (HFur), compounds with chemical compositions [Cu2(Fur)4(MeCN)2] (I) and [Mg2(Fur)4(H2O)5]∙ MeCN∙H2O (II) are synthesized. According to the X-ray diffraction data (CIF files CCDC nos. 2085817 (I) and 2085818 (II)), both complexes have a binuclear structure. The metal core of I correspond to the tetracarboxylate bridged {Cu2(μ-Fur)4} complex, the coordination number of the copper atom in which is 5 (CuNO4); in II, the metal atoms are linked by two carboxylate groups and a water molecule, and the coordination environment of the metal centers is completed to the polyhedron (MgO6) by oxygen atoms of the Fur– anions and water molecules. According to EPR spectroscopy data, exchange-coupled copper(II) dimers with a substantial zero-field splitting are observed in I. For I and II, antibacterial activity against the nonpathogenic strain of M. smegmatis, and cytotoxicity against human ovarian adenocarcinoma cells SCOV3 and normal human fibroblast cells of the HDF line have been determined. [ABSTRACT FROM AUTHOR]

Abstract—A mixed corrosion inhibitor (CI), which is an equimolar composition of sodium oleyl sarcosinate (SOS) and sodium flufenaminate (SFF), to protect the D16 aluminum alloy from atmospheric corrosion has been studied here. Polarization measurements used to assess the efficiency of preliminary passivation of the alloy with solutions of SOS, SFF, and their composition showed significant advantages of mixed CI. The features of CI adsorption on the surface of the D16 alloy are studied by XPS. It has been established that the adsorption of SOS and SFF separately results in the formation of monolayer coatings firmly bound to the alloy surface with a thickness of no more than 2.6–3.2 nm. When these CIs are adsorbed together, the layer thickness reaches 12–20 nm. This layer contains significant amounts of Al3+ ions (~20%) related to compounds with SFF and SOS, as well as aluminum hydroxides. A possible mechanism for the formation of such a protective layer is proposed. The results of corrosion tests in a humid atmosphere with daily condensation of moisture on D16 alloy samples confirm the high protective ability of the mixed CI. [ABSTRACT FROM AUTHOR]