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Considering the increasing demand for gold and the scarcity of mineral resources, this study presents a promising avenue for its recovery from secondary resources. In this paper, N1,N1′-(1,4-phenylene)bis(N1-(4-aminophenyl)benzene-1,4-diamine) and 2,3,5,6-tetrafluoro-p-dibenzaldehyde were successfully prepared by the solvothermal method to synthesize a highly fluorinated covalent organic polymer with imine bonds (N-TFACOP), which can be used to recover gold ions from secondary sources. Covalent organic polymer (COP) materials have controllable structures that can be significantly improved by introducing appropriate functional groups into the structural units. The introduction of fluorine atoms with strong electron-absorbing ability into COP materials not only significantly increases the specific surface area of the materials and provides more surface active sites but also improves the chemical and thermal stability of the materials, even in strong acids and bases. The adsorption capacity for gold was further improved. At pH = 4, adsorption time of 720 min, and adsorption temperature of 45 °C, the maximum adsorption capacity of N-TFACOP for gold was as high as 2975.08 mg g−1. There was no significant decrease in the adsorption rate after six cycles, which proved that the adsorption performance for gold was significantly improved by N-TFACOP. Au(III) was reduced to monomeric gold by complexation and redox reaction between the functional atom (N) and Au(III). In summary, we verified the adsorption potential of a novel covalent organic polymer for Au(III), which provides a strong reference for the recycling of the precious gold metal from secondary resources and the protection of environmental resources. [ABSTRACT FROM AUTHOR]

BACKGROUND: Selective catalytic reduction (SCR) can effectively remove NOx from flue gas in a coal‐fired power plant. As the core of SCR technology, the catalyst has a limited lifespan. The process of reducing acid leaching and roasting water leaching can efficiently extract vanadium and tungsten from spent SCR catalyst. For vanadium recovery in solution, the traditional vanadium precipitation process by NH4Cl has the disadvantages of consuming high precipitant dosage and producing large amounts of waste water. RESULTS: This study focused on the vanadium precipitation process using a solution containing vanadium obtained from adopting some steps to handle the spent SCR catalyst. First, melamine was screened out as the vanadium precipitant. Then, the vanadium precipitation conditions were optimized as follows: solution pH value of 1.0, n(C3H6N6)/n(V) = 0.8, 110 °C and 30 min. Under the best precipitation conditions, the vanadium precipitation efficiency of melamine can reach 99.32%. Finally, the mechanisms of vanadium precipitation by NH4Cl and melamine were discussed, respectively. CONCLUSION: The results showed that the vanadium precipitation process by NH4Cl followed the chemical reactions between NH4+ and vanadium ions, while the vanadium precipitation process by melamine followed the redox and complexation reactions which essentially belonged to the types of chemical adsorption. The vanadium precipitation product was roasted at 550 °C for 2 h to obtain the vanadium product. The main component of the vanadium product was V2O5, with a purity of 93.27 wt%. The total recovery efficiency of vanadium from spent SCR catalyst was 78.24%. © 2024 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

Abstract\nNOVELTY STATEMENTThe toxic Cr(VI) contaminating water released from the metallurgical, dyeing, and electroplating industries is getting worse day by day and is extremely hazardous to human health. Thus, the development of a cost-effective, quick, and efficient adsorbent is highly essential for the Cr(VI) decontamination from wastewater. Herein, a microwave-assisted carbon-based composite called Mg-Fe LDH@OPAC was prepared by assembling Mg-Fe LDH onto orange peel-activated carbon (OAPC). Prior to investigating deeply into the adsorption behavior of the composite, the Mg-Fe LDH@OPAC formation was confirmed by using instrumental techniques like FESEM, EDS, Zeta potential, XRD, FTIR, Raman, XPS, and BET analyzer. The material had a high surface area of 143.9 m2/g and showed a good monolayer Langmuir uptake capacity of 118.36 mg/g. Under ideal circumstances, the maximum amount of Cr(VI) was removed within just 120 min and showed high efficiency in the presence of other coexisting anions respectively. The adsorption was accounted by pseudo-second-order kinetics and spontaneous in nature. Ultimately, a possible adsorption mechanism was suggested, confirmed by XPS studies; which showed that oxidation-reduction, electrostatic interaction, and surface complexation reaction were responsible for Cr(VI) adsorption on Mg-Fe LDH@OPAC surface.Environmental contaminants like Cr(VI) in drinking water are highly toxic, and their long-term persistence in the water environment causes mutagenic effects on human beings. We present a novel material for the first time (yet not been reported) by intercalating activated carbon (from a low-cost wedge of orange peel) into Mg-Fe layered double hydroxide (abbreviated as Mg-Fe LDH@OPAC), which has superior hazardous hexavalent chromium metal uptake capability. With the order of SO42->F->CO32->I->PO43->NO3- the as-prepared Mg-Fe LDH@OPAC exhibits strong selectivity toward Cr(VI) in the presence of varied competing ions with a modest drop in removal effectiveness. The combined properties of AC and LDH make Mg-Fe LDH@OPAC potentially efficient adsorbent to remove Cr(VI) from the different water sources and potentially applied in wastewater treatment. [ABSTRACT FROM AUTHOR]

Compacted bentonite is part of the multi-barrier system of radioactive waste repositories. The assessment of the long-term performance of the barrier requires using reactive transport models. Here we present a multiphase flow and reactive transport benchmark for radioactive waste disposal. The numerical model deals with a 1D column of unsaturated bentonite through which water, dry air and CO 2 (g) may flow and with the following reactions; aqueous complexation, calcite and gypsum dissolution/precipitation, cation exchange and gas dissolution. INVERSE-FADES-CORE V2, DuMu X , TOUGHREACT and iCP were benchmarked with 6 test cases of increasing complexity, starting with conservative tracer transport under variably unsaturated conditions and ending with water flow, gas diffusion, minerals and cation exchange. The solutions of all codes exhibit similar trends. Small discrepancies are found in conservative tracer transport due to differences in hydrodynamic dispersion. Computed CO 2 (g) pressures agree when a sufficiently refined grid is used. Small discrepancies in CO 2 (g) and pH are found near the no-flow boundary at early times which vanish later. Discrepancies are due differences in the formulations used for gas flow at nearly water-saturated conditions. Computed CO 2 (g) pressures show a fluctuation between 10 - 4 and 10 - 3 years which slows down the in-diffusion of CO 2 (g) . This fluctuation is associated with chemical reactions involving CO 2 . There are discrepancies in solute concentrations due to differences in the Debye–Hückel (DH) formulation. They are overcome when all codes use the same DH formulation. The results of this benchmark will contribute to increase the confidence on multiphase reactive transport models for radioactive waste disposal. [ABSTRACT FROM AUTHOR]

The proton transfer (PT) complexation reaction between 3,4-diaminopyridine (3,4-DAP), an important drug, and 2,6-dichloro-4-nitrphenole (DCNP) was investigated experimentally and theoretically. The experimental results indicated a chemical reaction occurred because of a hydrogen bonding, followed by proton transfer from the DCNP to the 3,4-DAP in different polar media. The Benesi–Hildebrand equation was used to estimate the formation constant (Kf), molar absorptivity (εPT), and other physical parameters. The formed PT complex was characterized using FTIR, 1H, and 13C NMR spectra. In addition, the nanocrystalline structure, particle sizes, and surface morphology of the complex were investigated by XRD and SEM-EDX. The structure of the 1:1 PT complex was calculated theoretically in the gas phase and the presence of solvent effects. Using TD-DFT calculations, the band observed at 406 nm (Calc. 379.5 nm) and 275 nm (Calc. 272.3 nm) could be assigned to the HOMO→LUMO transition (99%), and HOMO→L+3 transition (87%), respectively. The DNA binding ability of the PT complex was investigated, revealing an intercalative binding mechanism with a binding constant Kb of 4.6 × 104 M−1. Based on the results of the Ct-DNA binding study, the binding free energy of the PT complex with the receptor of human DNA (PDB ID:1BNA) is found to be −7.2 kcal/mol. The cytotoxic effects of the PT complex were evaluated on selected cancer cell lines, demonstrating significant antitumor activity against A-549 and MCF-7 cancer cell lines. [ABSTRACT FROM AUTHOR]

The improper disposal of uranium mine tailings and smelting wastewater poses significant environmental hazards, including contamination of water bodies and soil, and potential health risks to humans through the accumulation of uranium in bones and organs. This study examines the removal of hexavalent uranium (U(VI)) from water using biochar derived from agricultural waste enhanced by hydrogen peroxide (H2O2) and magnetization modifications involving the incorporation of Fe3O4 nanoparticles onto the biochar surface. The adsorption capacities were evaluated through batch experiments, and the mechanisms were analyzed using SEM, FT-IR, XPS, and BET surface analysis. These modifications were found to significantly increase the biochar's specific surface area from 17.606 m2/g to 195.62 m2/g and pore volume from 0.037 cm3/g to 0.132 cm3/g, and surface enrichment with oxygen-containing functional groups, particularly carboxyl groups. The inherent adsorption efficiency of biochar for U(VI) is significantly enhanced by these modifications, with the adsorption capacities of H2O2-modified (HBC) and magnetized HBC (MBC) reaching 69.50 mg/g and 77.58 mg/g, respectively. The adsorption mechanisms of BC, HBC, and MBC for U(VI) involve complexation reactions where hydroxyl and carboxyl groups, among other oxygen-containing functional groups on the biochar, interact with uranyl ions. HBC and MBC exhibit enhanced complexation due to higher carboxyl content, leading to improved U(VI) adsorption. Additionally, the presence of iron-containing functional groups on the surface of MBC contributes to electrostatic interactions and facilitates complexation reactions between Fe-O and uranyl ions, enhancing the overall adsorption process. These findings highlight the potential of modified biochar for the removal of U(VI) from water, particularly for the treatment of mine tailings and smelting wastewater, with significant implications for industrial applications in environmental remediation. [ABSTRACT FROM AUTHOR]

Wastewater produced in beryllium mining seriously affects ecological balance and causes great environmental pressure. We designed a novel porous lotus leaf biochar modified with PO43−/NH4+ multifunctional groups (MLLB) and used it for beryllium(Be) removal from beryllium mining wastewater. Kinetic and thermodynamic experiments showed that the adsorption capacity (Qe) of Be with MLLB from the simulated beryllium mining wastewater could reach 40.38 g kg−1 (35 °C, pH = 5.5), and the adsorption process was spontaneous and endothermic. The dispersion coefficient Kd of Be with MLLB was 2.6 × 104 mL g−1, which proved that MLLB had strong selective adsorption capacity for Be. Phosphoric acid, ammonia, and hydroxyl groups on the MLLB surface would complex with Be to form Be(OH)2 and Be(NH4)PO4 complexation products, which implied that surface complexation and precipitation reactions might co-existed in the adsorption process. The above results showed that MLLB could effectively adsorb Be and prevent beryllium exposure in a beryllium mining process. [ABSTRACT FROM AUTHOR]

Compounds of natural origin found in varying quantities in plant-based products constitute a highly significant category, possessing structural significance as well as the capacity to regulate oxidative processes. The activity of these compounds may be modulated by the composition of the biological environment in which they operate, the pH of the environment, or the presence of metal cations in plants or plant extracts. A successful complexation reaction was mainly confirmed by FT-IR, observing the shift from the original transmittance of catechin bonds, especially O-H ones. This work shows the synthetic methodology and the optimization process that took place to synthesize a catechin–copper complex, which demonstrated antioxidant activity. It was tested for iron chelation ability, hydroxyl radicals, and the inhibition of lipoxygenase (15-LOX). An antidiabetic assay was performed by determining the inhibition of alpha-amylase and alpha-glucosidase, finding that the synthesized complex had similar inhibitory potential as pure catechin. The antibacterial tests showed results against Staphylococcus aureus and the antifungal properties of the complex against Candida albicans. [ABSTRACT FROM AUTHOR]

The application of low-cost biosorbent of bamboo in methylene blue (MB) removal treatment is limited by its poor adsorption performance. In this study, bamboo parenchyma cell (BP) was isolated from bamboo powder by facile method of water separation and then incorporated with natural non-toxic vermiculite (VE) to prepare bamboo parenchyma cell-vermiculite (VEBP) composites. Much more nanopores were formed and more active adsorbed sites were introduced by filling with VE in BP lumen, which is favorable for improving the MB adsorption capacity. The MB adsorption isotherm of VEBP was preferably fitted with Langmuir model, yielding the highest equilibrium MB adsorption capacity of approximately 422 mg/g. As-obtained adsorption capacity is much higher than that of BP and various kinds of biosorbents in previous researches. Besides, the adsorption kinetics was closer to the pseudo-second-order model, indicating the dominant chemisorption process. Thermodynamic parameters implied the endothermic and spontaneous as well as entropy-governed adsorption process. Based on the analysis of adsorption behavior together with characterizations of VEBP, it can be confirmed that the predominant mechanisms for MB adsorption may involve electrostatic attraction, ion exchange, hydrogen bonding, pore filling, complexation reaction, and π-π interactions. Furthermore, the VEBP exhibited excellent reusability with MB removal efficiency of more than 80% after five cycles. Therefore, this study successfully provides a facile method for preparation of bamboo-based adsorbent with efficient MB adsorption performance. [ABSTRACT FROM AUTHOR]

This study demonstrates the preparation of a unique chitosan (CS)/polymethyl methacrylate (PMMA)/polyethyleneimine (PEI) nanofiber (NF) membrane using PMMA as the composite skeleton through an electrospinning method. The chemical and mechanical properties, chromium (Cr) adsorption capabilities, and mass transfer mechanisms of the NF membrane were thoroughly investigated. The findings indicate that the CS/PMMA/PEI NF membranes, with an average diameter of approximately 856.2 nm, exhibits favorable hydrophilicity, effective Cr(VI) adsorption (first adsorption capacity of 226.5 mg g−1), and robust mechanical properties (tensile strength of 1.58 ± 0.092 Mpa), which is superior to most reported adsorbents. Moreover, the composite NF membranes exhibit a second adsorption capacity of 194.4 mg g−1 and a tensile strength of 0.739 ± 0.072 Mpa after the second adsorption, indicating a remarkable level of reusability and cycle stability. Additionally, x‐ray photoelectron spectroscopy, and structural tests reveal the presence of abundant amino (NH2) and hydroxyl (OH) groups in the CS/PMMA/PEI NF membranes, suggesting potential sites for complexation reactions and the reductions of Cr(VI) ions, thereby facilitating effective adsorption and removal of heavy metals. This study introduces a novel and straightforward approach for synthesizing highly effective adsorbents, with have potential implications for the removal of heavy metal ions from wastewater. [ABSTRACT FROM AUTHOR]

A new sustainable heterogeneous catalyst for the effective synthesis of 4H-pyran derivatives under mild reaction conditions was investigated. This heterogeneous catalyst was prepared through the complexation reaction between the naturally obtained chitosan from Callinectes sapidus shells and zinc(II) ions (Zn(II)/Chitosan), and characterized using a variety of techniques, including thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), and infrared spectroscopy (IR). The corresponding 4H-pyran derivatives were obtained in good to excellent yields (58–96%) in the presence of Zn(II)/chitosan catalyst using water as solvent at 60°C for only 20 min. The catalyst was easily separated from the reaction mixture by simple filtration, resulting in the desired products with excellent purity. In comparison to numerous other catalyst systems for the synthesis of 4H-pyran derivatives, Zn(II)/chitosan, a new sustainable heterogeneous catalyst, demonstrated remarkable efficacy in an environmentally benign solvent, allowing the desired products to be produced under more environmentally friendly reaction conditions. [ABSTRACT FROM AUTHOR]

A lanthanum–cerium-based abrasive composed of CeO2, LaOF, and LaF3 was commercially obtained. The effect of sodium hexametaphosphate (SHMP) on powder dispersion behavior was systematically investigated using the combined techniques of liquid contact angle, turbidity, zeta potential (ZP), scanning electron microscopy (SEM), powder X-ray diffraction (XRD) combined with Rietveld refinements, X-ray photoelectron spectroscopy (XPS), and polishing tests. The results indicated that the addition of 0.5 wt.% SHMP dispersant to the 5 wt.% lanthanum–cerium-based slurry produced the most stable suspension with a high turbidity of 2715 NTU and a low wetting angle of 45°. The as-obtained slurry displayed good surface polishing quality for K9 glass, with low surface roughness (Ra) of 0.642 and 0.515 nm (in the range of 979 × 979 μm2) at pH = 6 and 11, respectively, which corresponds to the fact that it has local maximum absolute values of ZP at these two pH values. SEM images demonstrated that after appropriate grafting of SHMP, the particle aggregation was reduced and the slurry's dispersion stability was improved. In addition, the dispersion mechanism was explained based on the principle of complexation reaction, which reveals that the dispersant SHMP can increase the interparticle steric hindrance and electrostatic repulsions. In an acidic environment, steric hindrance dominates, while electrostatic repulsion prevails under alkaline conditions. As expected, this polishing slurry may find potential applications in manufacturing optical devices and integrated circuits. [ABSTRACT FROM AUTHOR]

Excessive oxidative stress (OS) in the peri-implant environment is commonly considered to be an important reason for poor implant osseointegration, and numerous approaches have been developed for improving antioxidant capability of implants. However, it remains challenging to alleviate multiple OS factors in the peri-implant environment. Herein, we reported a facile and effective surface modification method to construct a mussel-inspired epigallocatechin gallate (EGCG)/nano-ceria coating with multiple antioxidant capacities on the titanium surface based on the combination of polyphenol–metal complexation and hydrothermal reaction, which consisted of antioxidative EGCG and CeO2 nanoenzyme to mimic the multiple antioxidant mechanisms of living organisms. The effects of preparation conditions on the morphology, structure, multiple enzyme-like activities, and free radical scavenging ability of the coatings were investigated. The optimized EGCG/nano-ceria coating demonstrated good inhibition efficacy on multiple OS factors, non-toxicity, and improved osteogenetic activities with upregulated alkaline phosphatase expression and calcium deposition even under the simulated OS environment. The results indicated that EGCG/nano-ceria coating with multiple antioxidant capacities showed great potential for enhancing osteogenesis of titanium implants, and also suggested a promising bio-inspired surface modification strategy for improving the biological function of implant materials. [ABSTRACT FROM AUTHOR]

Heavy metals are particularly damaging contaminants in the environment, and even trace concentrations represent a risk to human health due to their toxicity. To detect the heavy metals of Mn2+ and Co2+ ions, a novel selective reusable paper-based Fluorescence naked-eye sensor based on naphthalene cationic Schiff base (NCSB) was synthesized and confirmed using FT-IR, 1 H-NMR, and MS tools. Based on a blue to colorless color change in the aqueous solution, the NCSB sensor is utilized to Mn2+ and Co2+ cations selectively among other metal ions (Fe2+, Cu2+, Mg2+, Ni2+, Zn2+, Cd2+, Hg2+, Pb2+, Sn2+ and Cr3+). In the aqueous medium, the NCSB sensor displayed high sensitivity, with limits of detection (LOD) values of 0.014 µM (14.08 nM) and 0.041 µM (41.47 nM) for Mn2+ and Co2+ cations, respectively. The paper-based sensor naked-eye detected Mn2+ and Co2+ cations in water at concentrations as low as 0.65 µM (65 nM) and 0.086 µM (86 nM), respectively. It was discovered that 5 min of incubation time and a pH range of 7 to 11 were optimal for the complexation reaction between the Mn2+ and Co2+ ions and the NCSB sensor. Through a static quenching process, the interaction of the different metal ions with the Schiff base group in the NCSB molecule results in the development of a ground-state non-fluorescent complex. NCSB sensor was also successfully applied in analysis of Mn2+ and Co2+ in environmental water with good recoveries of 94.8–105.9%. The theoretical calculations based on density functional theory (DFT) studies are in support of experimental interpretations. The links between the input factors and the anticipated response were evaluated using the quadratic model of the response surface methodology (RSM) modeling. [ABSTRACT FROM AUTHOR]

A series of metalloligands bearing homoleptic 2,2′:6′,2′′-terpyridine (tpy)-CdII complexes has been successfully synthesized. The formation of ML1 was accomplished through a sequence of Suzuki–Miyaura coupling and complexation reactions, offering an alternative method to produce tpy-based metalloligands under relatively mild conditions. Moreover, the metallomacrocycle C1 and metallocatenane C2 were self-assembled from heteroleptic complexation reactions involving ML1 and suitable counterparts. [ABSTRACT FROM AUTHOR]

Lead(II) complexation reactions were studied in the presence of salts of the closo-decaborate anion [B10H10]2– and azaheterocyclic ligands 2,2'-bipyridyl (bipy) or 1,10-phenanthroline (phen) in water and organic solvents (acetonitrile, DMF). Binuclear complex Pb(bipy)2[B10H10] and polymer complex [Pb(phen)[B10H10]] were isolated. The effect of solvents and reagent ratios on the composition and structures of the final complexes was studied. The complex compounds were identified by elemental analysis, IR spectroscopy, and X-ray powder diffraction. The structure of complex [Pb(bipy)2[B10H10]]2·2CH3CN (CCDC no. 2325841) was determined by single-crystal X-ray diffraction. [ABSTRACT FROM AUTHOR]

Low molecular weight organic acids often influence the surface reactions (adsorption/ precipitation) of minerals, which in turn affect the stability of elemental transport in environmental geochemical processes. The effect of malic acid on calcite-fluorine adsorption/ precipitation reactions was investigated. The results show that at the initial pH of 7.7 and lower F concentrations (5 mg·L-1¯), as the concentration of malic acid increases, its surface adsorption capacity becomes stronger and exhibits the inhibitory effects on F removal; at the F concentrations of 25 or 60 mg·L-1, the dominant mechanism of F removal is CaF2 precipitation; the intervention of malic acid shows little inhibition of the CaF, precipitation reaction; the stronger adsorption reaction of malic acid results in an increase of pH and a decrease in Ca concentration. At the initial pH of 8. 3 and low F concentration (<20 mg·L-1), malic acid still inhibits F removal through its competitive adsorption; as the concentration of malic acid increases, its effect of complexation with Cat results in a constant increase in pH and Ca concentration; at the medium F concentration of 60 mg·L-1, the dominant mechanism of F removal has been shifted to CaF2 precipitation; 20 mg·L-1 malic acid has inhibited it, and as the malic acid continues to increase, the pH value decreases and then increases, and the Ca concentration continues to increase, highlighting the effect of the malic acid complexation reaction; At high F concentration of 100 mg·L-1, 100 mg·L-1 malic acid greatly inhibits the CaF2 precipitation reaction, corresponding to a pH value that do not exceed that of the malic acid- free condition; the corresponding Ca concentration is still lower than its blank background value. implying the dominance of the CaF2 precipitation reaction. At the initial pH of 8.7, malic acid has a weak inhibition to F removal at low F concentration (5 mg·L-1); however, as the concentration of malic acid increases, the effect of its complexation reaction becomes much clearer, which results in a significant increase in both pH and Ca concentration; at high F concentration of 240 mg·L-1, the dominant mechanism for F removal is the CaF2 precipitation reaction, which is inhibited with increasing malic acid concentration, with increasing Ca concentration showing the effect of malic acid complexation, and decreasing pH values indicating the dominance of the CaF2 precipitation reaction. This study is important for the stability assessment of calcite minerals in organic acid-rich environments, and also provides a reference for the study of fluorine transport transformation on other minerals. [ABSTRACT FROM AUTHOR]

Fe/Mn (hydr)oxides are metallic compounds that exhibit significant redox activity in environmental media and play a pivotal role in geochemical processes, thereby influencing the fate of metals in porous media. The morphology of Fe/Mn (hydr)oxides in natural environments and their interactions with trace metals are significantly influenced by the presence of natural organic matter (NOM). However, there is limited understanding regarding the formation, transport, and stability of Fe/Mn (hydr)oxides in the environment. The present study employed humic acid (HA) as a representative NOM material to investigate the positive influence of HA on the formation of Fe/Mn colloids. However, there remains limited comprehension regarding the formation, transport, and stability of Fe/Mn (hydr)oxides in the natural environment. In this study, we investigated the positive effect of natural organic matter (NOM) on the formation of Fe/Mn colloids using humic acid (HA) as a representative NOM material. We comprehensively characterized the chemical and physical properties of HA–Fe/Mn colloids formed under various environmentally relevant conditions and quantitatively analyzed their subsequent aggregation and stability behaviors. The findings suggest that the molar ratios of C to Fe/Mn (hydr)oxide play a pivotal role in influencing the properties of HA–Fe/Mn colloids. The formation and stability of HA–Fe/Mn colloids exhibit an upward trend with increasing initial molar ratios of C to Fe/Mn. Redox and metal–carboxylic acid complexation reactions between HA and hydrated iron/manganese oxides play a pivotal role in forming colloidal HA–Fe/Mn complexes. Subsequent investigations simulating porous media environments have demonstrated that the colloidal structure resulting from the interaction between HA and Fe/Mn facilitates their migration within surrounding porous media while also enhancing their retention in the surface layers of these media. This study offers novel insights into the formation and stabilization mechanisms of HA–Fe/Mn colloids, which are pivotal for comprehending the behavior of Fe/Mn colloids and the involvement of Fe/Mn (hydr)oxides in geochemical cycling processes within porous media. [ABSTRACT FROM AUTHOR]

A novel type of nanocomposite‐modified electrodes, synthesized from ZIF67 and mesoporous carbon nitride (CN) featuring a carbonyl heterocyclic ring, were meticulously fabricated via an alkali‐mediated method. This innovative approach led to the construction of high‐performance electrochemical sensors. Utilizing differential pulse voltammetry, these sensors demonstrated significant potential for the precise detection of glyphosate in various aqueous environments. The detection mechanism of this sensor operates through the complexation reaction between Co2+ and glyphosate, resulting in a decrease in the response current. The fabricated material was characterized using scanning electron microscopy, transmission electron microscopy, X‐ray diffraction techniques, X‐ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy to verify its morphology and structure. The results demonstrated that the sensor exhibited high sensitivity, with a detection limit of 0.04 pg/L and a linear range from 10−12–10−5 g/L, showcasing good selectivity for glyphosate. In tests evaluating the sensor's effectiveness for detecting glyphosate in real water samples, recovery rates ranged from 97 %–106 %, further attesting to its high accuracy and practicality. [ABSTRACT FROM AUTHOR]

Developing multifunctional engineered adsorbents is an effective strategy for decontaminating the environment from various pollutants. In this study, a polyfunctionalized carbon-framework composite, MSC-CFM, was synthesized. The composite comprises an aromatic carbon framework enriched with various functional groups, including magnetic nanoparticles, hydroxyl, and amino groups. MSC-CFM was used to decontaminate Cr(VI) and polycyclic aromatic nitrides (p-dimethylaminoazobenzene sulfonate (DAS) and diphenyl-4, 4 '-di [sodium (azo-2 -) -1-amino-naphthalene-4-sulfonate] (DANS)) from acidic wastewater. The adsorption capacities of MSC-CFM for Cr(VI), DAS and DANS, quantified using the Langmuir isotherm model, were 161.28, 310.83, and 1566.09 mg/g, respectively. Cr(VI) and PAHs (DAS and DANS) were monolayer adsorbed controlled by chemisorption. MSC-CFM could maintain good adsorption efficiency after up to 6 adsorption and desorption cycles. The presence of polycyclic aromatic nitrides promoted the adsorption of Cr(VI) in the Cr(VI)-DAS/DANS binary systems. Removal of pollutants by MSC-CFM involved a variety of unreported reaction mechanisms, such as electrostatic attraction, redox reaction, anion exchange, intermolecular hydrogen bonding, complexation reaction, π-π interaction, and anion-π interaction. MSC-CFM, enriched with a variety of functional groups, is a promising new material for environmental protection. It has good potential for practical application in treating polluted wastewater. [ABSTRACT FROM AUTHOR]

AbstractA portable device for digital image colorimetry (DIC) is reported for the determination of Ca in crude oil emulsions. ASTM D4807 was used for sample preparation for the isolation of saline species containing Ca. DIC was evaluated based on the complexation reactions with Ca using calcein, murexide, and calcon. Partial least squares (PLS) provided the best determination coefficients (higher than 0.990) for all complexing reagents. Significant interference of Mg was observed for the determination of Ca using calcein. PLS models with the lowest root mean square error of cross validation (RMSECV) values were obtained for murexide and calcon for a concentration of 0.250 mmol L−1 at pH of 13. The best conditions for camera focal length were 11 and 2 mm for murexide and calcon. For light intensity, the optimized conditions for murexide and calcon was 180 lux. Stabilities of color complexes over the time were 30 and 15 min for murexide and calcon, respectively. DIC/murexide provided the lowest root mean square error of prediction (RMSEP) and a linear response was observed from 0.5 to 10 mg L−1 Ca and the relative standard deviation (RSD) was lower than 10%. Significant differences were not observed between the results obtained by DIC/murexide and those obtained by microwave-assisted wet digestion (MAWD) with determination by inductively coupled plasma-optical emission spectrometry (ICP-OES). A limit of quantification of 0.50 mg kg−1 Ca were obtained using DIC/murexide. This approach is an alternative and useful method for the determination of Ca in crude oil samples, with advantages of miniaturization, low cost, and ease of operation. [ABSTRACT FROM AUTHOR]

The development of new drugs derived from plant sources is of significant interest in modern pharmacy. One of the promising plant sources for introduction into pharmaceuticals is Tripleurospermum inodorum (L.) Sch. Bip., also known as Tripleurospermum perforatum (Merat.) M. This plant has been shown to possess various biological activities, including anti-inflammatory, antimicrobial, and antimycotic activities, among others. However, a review of the current literature reveals a paucity of studies investigating the chemical composition of the herb Tripleurospermum inodorum (L.) Sch. Bip. This study presents the development of a method for obtaining an extract of the herb Tripleurospermum inodorum (L.) Sch. Bip. enriched with flavonoids, harvested before flowering and butonization. This study focused on determining the optimal conditions for extraction, including the concentration of the extractant (ethanol), extraction time, raw material/extractant ratio, extraction frequency, complexation reaction time, amount of aluminum chloride solution, and amount of diluted acetic acid. The results indicate that herbs harvested during this specific period exhibited a higher flavonoid content compared to those collected during butonization and flowering. Moreover, this study demonstrated that the flavonoid content could exceed 7% mg REq/100 g D.W. through a one-hour extraction process. Furthermore, the flavonoid content was found to be 7.65 ± 0.03 mg REq/100 g D.W. following a three-minute ultrasound-assisted extraction process, followed by thermal extraction. A qualitative analysis identified a variety of phenolic compounds in the extract, such as chlorogenic acid, 5-O-p-coumaroylquinic acid, 1-O-p-coumaroylquinic acid, luteolin-7-glucoside, quercetin-3-glucoside, luteolin-7-rutinoside, 3,5-O-dicaffeoylquinic acid, quercetin-3-O-malonylglucoside, apigenin-7-glucoside, luteolin-3-malonylglucoside, cynarin, rhamnetin-3-(O-dimethyl rhamnosyl glucosylglucoside), and luteolin. Moreover, this study demonstrated the antimicrobial, anti-inflammatory, anticoagulant, anti-aggregation, and antioxidant activities of the aqueous alcoholic extract from T. inodorum herb (ETIH) against pathogens such as Staphylococcus aureus, Escherichia coli, and Candida albicans. Additionally, the extract exhibited comparable anti-inflammatory effects on diclofenac sodium. These findings contribute to the understanding of the potential pharmacological applications of the developed herb extract. [ABSTRACT FROM AUTHOR]

Rising organic charge in northern freshwaters is attributed to increasing levels of dissolved natural organic matter (DNOM) and changes in water chemistry. Organic charge concentration may be determined through charge balance calculations (Org.−) or modelled (OAN−) using the Oliver and Hruška conceptual models, which are based on the density of weak acid functional sites (SD) present in DNOM. The charge density (CD) is governed by SD as well as protonation and complexation reactions on the functional groups. These models use SD as a key parameter to empirically fit the model to Org.−. Utilizing extensive water chemistry datasets, this study shows that spatial and temporal differences in SD and CD are influenced by variations in the humic-to-fulvic ratio of DNOM, organic aluminum (Al) complexation, and the mole fraction of CD to SD, which is governed by acidity. The median SD values obtained for 44 long-term monitored acid-sensitive lakes were 11.1 and 13.9 µEq/mg C for the Oliver and Hruška models, respectively. Over 34 years of monitoring, the CD increased by 70%, likely due to rising pH and declining Al complexation with DNOM. Present-day median SD values for the Oliver and Hruška models in 16 low-order streams are 13.8 and 15.8 µEq/mg C, respectively, and 10.8 and 12.5 µEq/mg C, respectively, in 10 high-order rivers. [ABSTRACT FROM AUTHOR]

In this paper, we have examined eight new first‐row transition metal complexes (1–8). Mutli‐donor ligands based on barbituric and thiobarbituric acids were used in complexation reactions. The synthesized complexes were analyzed using FT‐IR and UV–vis spectroscopy, elemental (CHN) analysis, and single‐crystal X‐ray diffraction analysis. These complexes exhibited significant urease enzyme inhibition with IC50 values in the range of 13.73 ± 1.08–43.21 ± 1.50 μM. We observed excellent binding orientation of these complexes in the active site of Urease. The molecular docking results correlate well with in vitro observations. [ABSTRACT FROM AUTHOR]

Background: Positron emission tomography (PET) is a highly sensitive method that provides fine resolution images, useful in the field of clinical diagnostics. In this context, Zirconium-89 (89Zr)-based imaging agents have represented a great challenge in molecular imaging with immuno-PET, which employs antibodies (mAbs) as biological vectors. Indeed, immuno-PET requires radionuclides that can be attached to the mAb to provide stable in vivo conjugates, and for this purpose, the radioactive element should have a decay half-life compatible with the time needed for the biodistribution of the immunoglobulin. In this regard, 89Zr is an ideal radioisotope for immuno-PET because its half-life perfectly matches the in vivo pharmacokinetics of mAbs. Results: The main objective of this work was the design and synthesis of a series of bifunctional octadentate pseudopeptides able to generate stable 89Zr complexes. To achieve this, here we investigated hydroxamate, N-methylhydroxamate and catecholate chelating moieties in complexing radioactive zirconium. N-methylhydroxamate proved to be the most effective 89Zr-chelating group. Furthermore, the increased flexibility and hydrophilicity obtained by using polyoxyethylene groups spacing the hydroxamate units led to chelators capable of rapidly forming (15 min) stable and water-soluble complexes with 89Zr under mild reaction conditions (aqueous environment, room temperature, and physiological pH) that are mandatory for complexation reactions involving biomolecules. Additionally, we report challenge experiments with the competitor ligand EDTA and metal ions such as Fe3+, Zn2+ and Cu2+. In all examined conditions, the chelators demonstrated stability against transmetallation. Finally, a maleimide moiety was introduced to apply one of the most promising ligands in bioconjugation reactions through Thiol-Michael chemistry. Conclusion: Combining solid phase and solution synthesis techniques, we identified novel 89Zr-chelating molecules with a peptide scaffold. The adopted chemical design allowed modulation of molecular flexibility, hydrophilicity, as well as the decoration with different zirconium chelating groups. Best results in terms of 89Zr-chelating properties were achieved with the N-methyl hydroxamate moiety. The Zirconium complexes obtained with the most effective compounds were water-soluble, stable to transmetallation, and resistant to peptidases for at least 6 days. Further studies are needed to assess the potential of this novel class of molecules as Zirconium-chelating agents for in vivo applications. [ABSTRACT FROM AUTHOR]

In the present study, we report the solid-state isolation and structural characterization of novel iron(III) complexes of the veterinary antibiotic monensin. Monensic acid (MonH × H2O) forms a dinuclear complex of composition with FeCl3 [FeCl(Mon)2]2 (1), while its interaction with FeSO4 leads to the isolation of a triangular oxo-ferric coordination species [Fe3O(Mon × H2O)6(H2O)2(OH)] (2). During the procedure resulting in 2, oxidation of the Fe(II) ions by atmospheric oxygen was observed. In the presence of organic bases, both complexation reactions proceeded to successfully deprotonate the carboxylic function of the ligand. Iron(III) complexes 1 and 2 were characterized by IR, EPR, NMR, and Mössbauer spectroscopies as well as with thermal (TG-DTA/MS) and elemental analyses. In addition, the structures of the two coordination compounds were modelled and selected calculated parameters were compared with the experimental results. The biological assay revealed the enhanced antibacterial potential of the newly obtained complexes against the Gram-positive aerobic microorganisms Bacillus cereus and Bacillus subtilis. [ABSTRACT FROM AUTHOR]

Leishmaniasis is a group of parasitic diseases with the potential to infect more than 1 billion people; however, its treatment is still old and inadequate. In order to contribute to changing this view, this work consisted of the development of complexes derived from MI metal ions with thioureas, aiming to obtain potential leishmanicidal agents. The thiourea ligands (HLR) were obtained by reactions of p-toluenesulfohydrazide with R-isothiocyanates and were used in complexation reactions with AgI and AuI, leading to the formation of complexes of composition [M(HLR)2]X (M = Ag or Au; X = NO3− or Cl−). All compounds were characterized by FTIR, 1H NMR, UV-vis, emission spectroscopy and elemental analysis. Some representatives were additionally studied by ESI-MS and single-crystal XRD. Their properties were further analyzed by DFT calculations. Their cytotoxicity on Vero cells and the extracellular leishmanicidal activity on Leishmania infantum and Leishmania braziliensis cells were evaluated. Additionally, the interaction of the complexes with the Old Yellow enzyme of the L. braziliensis (LbOYE) was examined. The biological tests showed that some compounds present remarkable leishmanicidal activity, even higher than that of the standard drug Glucantime, with different selectivity for the two species of Leishmania. Finally, the interaction studies with LbOYE revealed that this enzyme could be one of their biological targets. [ABSTRACT FROM AUTHOR]

¹H-NMR spectroscopy was used to monitor the reactions of an arylidene 2-thiohydantoin derivative, 3-((phenylmethylene)amino)-2-thioxo-4-imidazolidinone (3), with PdCl2, cis-[PdCl2(dmso-S)2] and K2[PdCl4] in DMSO-d6 in order to elucidate the reaction kinetics and mechanism. The 2-thiohydantoin derivative 3 formed cis-[Pd(3-N,S)(dmso-S)2]+ complex (5) in reactions with PdCl2 and cis-[PdCl2(dmso-S)2], while no reaction with K2[PdCl4] was observed. A two-step mechanism for the reactions of 3 with PdCl2 and cis--[PdCl2(dmso-S)2] is proposed, in which fast coordination to the side chain nitrogen occurs in the first step, while chelation and coordination to the sulfur atom in the 2-thiohydantoin ring is the second, slower, rate-determining step. The reaction rate constants were calculated and reactivities of the 2-thiohydantoin derivative 3 towards the palladium(II) salts were compared and discussed. Reaction of 3 with cis-[PdCl2(dmso-S)2] was faster than with PdCl2. The investigated palladium(II) salts also react with the solvent, DMSO-d6, and the influence of these side reactions on the outcome and kinetics of the 2-thiohydantoin derivative complexation reaction is discussed in detail. The obtained results of this study can have an impact in explanation of the coordination behavior of antitumor active palladium(II) and platinum(II) complexes. [ABSTRACT FROM AUTHOR]

Trace metals (Mn, Ni, Cu, Zn and Pb) dynamics in the system soil–soil solution—uncultivated grass vegetation was investigated by experimental analytical studies of natural soil samples, uncultivated grass vegetation samples, as well as aqueous soil extracts prepared in laboratory. Additionally, thermodynamic modeling was applied to calculate the trace metals chemical species in these extracts. Two thermodynamic models were used—the classical ion-association model for calculating the inorganic metal species and the Stockholm Humic Model (SHM) accounting for the complexation reactions of trace metals with organic matter. The computer program Visual Minteq was used. Experimental data for the total concentrations of major and trace metals, dissolved organic carbon and pH were used as input data for the calculations. The highest mobility was registered for Mn, followed by Zn and Cu. No mobile Ni and Pb were extracted in water. The metal-organic species with fulvic acids were calculated to be dominant in the case of Cu and Zn, while inorganic species, mainly free ions and carbonates, were the dominant ones for Mn. The highest phytoaccumulation coefficients in the uncultivated grass vegetation were calculated for Cu and Zn, exceeding that of Mn by 1–2 orders of magnitude. Hence, it may be assumed that the domination of metal-organic species of Cu and Zn probably facilitates their phytoaccumulation in the examined vegetation. Despite the high Mn content in the aqueous soil extracts, its phytoavailability was very low, since organic complexes did not dominate for Mn. [ABSTRACT FROM AUTHOR]

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The preparation of iron ore tailings (IOTs) into supplementary cementitious materials (SCMs) is an effective approach to achieve value-added utilization of industrial solid waste. This study systematically investigates the hydration pattern and strength development of Portland cement systems with the incorporation of IOTs, steel slag (SS), granulated blast-furnace slag (GBFS), and fly ash (FA) under the action of different chemical additives. The hydration products, and microstructure and pore structure of the SCMs are analyzed using X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and mercury intrusion porosimetry. The findings of this study demonstrate that chemical activation plays a significant role in the strength development of SCMs. Among the five chemical activators tested, Triethanolamine (TEA) had the greatest influence on mechanical properties. The maximum compressive strength of the SCMs at 28 days was 42.9 MPa at a dosage of 1%. Specifically, the addition of TEA promotes volcanic ash reactions, and the high fineness of SCM provides nucleation sites for hydration products. Interactions between the volcanic ash reaction and the complexation reaction of TEA have a positive effect on compressive strength development. This research expands the potential for IOTs SCMs through chemical activation methods for value-added applications. [ABSTRACT FROM AUTHOR]

Conventional neutralization treatment for manganese (Mn)-bearing mine drainage provides a challenge of cost-efficiency, and new approaches should be explored for efficient removal of Mn. We focused on Mn neutralization sludge, a by-product of the Mn-bearing drainage treatment process, which was assumed to be useful as a water purification material. Mn and zinc (Zn) removal tests in simulated drainage were performed using Mn neutralization sludge, and the reaction mechanism was elucidated using geochemical modeling and X-ray absorption fine structure (XAFS) analysis. The results showed that the addition of sludge enabled to lower the Mn and Zn concentration below Japanese effluent standard (10 mg dm−3 for Mn; 2 mg dm−3 for Zn) within 1 h. Furthermore, heavy metal immobilization was achieved at neutral pH (7–8) with the sludge addition, while the conventional neutralization process without adding the sludge requires higher pH (>10) to lower Mn concentration. These removal behaviors were not explainable by considering only well-known phenomena: hydroxide precipitation, surface complexation reaction onto δ-MnO2, and autocatalytic Mn oxidation. Hence, we advanced the geochemical model for simulation, suggesting that a surface complexation reaction onto γ-MnOOH greatly contributed to the removal of Mn. Besides, Zn was calculated to be predominantly precipitated as ZnMn2O4. Solid residue analysis by XAFS measurement supported the result of above calculation, validating the reliability of the constructed geochemical model. Overall, we concluded that the advanced geochemical model would be useful in predicting the Mn and Zn behavior during mine drainage treatment with Mn neutralization sludge. [ABSTRACT FROM AUTHOR]

For further pharmaceutical applications, a novel Schiff base derivative of aminothiazole and its Co (II), Cu (II), Zn (II), and Th (IV) chelates were designed and prepared. For this purpose, 2‐aminothiazole and 2,4‐dihydroxybenzaldehyde have been coupled before the complexation reaction with the metal salts. Elemental analysis, FT‐IR, 1HNMR, UV–Vis spectra, transmission electron microscopy (TEM), X‐ray powder diffraction (XRD), molar conductance, and magnetic moment measurements were used to determine the structural formula of the ligand and its produced chelates. The acquired data pointed out that the ligand was chelated with metal through the nitrogen of azo group and deprotonated ortho phenolic oxygen atoms. In Cu (II) complex the copper ion chelated with two ligand molecules, whereas in other complexes the metal binds with one molecule only of ligand. It was shown by XRD patterns and high‐resolution TEM images that the complex particles had a uniform distribution across the chelates' surfaces and were nanometric in size. Extremely, antimicrobial and anticancer activity for the prepared ligand and complexes were investigated, which showed high activity, especially after complex formation. Docking studies have been performed to predict the compounds' efficacy as antitumor agents through their interaction with the co‐crystal structure of proteins for breast cancer cells (PDB ID: 3S7S) and protein of liver cancer 2 (PDB ID: 2JW2). The experimental results of the anticancer activity showed promising results, especially for Cu (II) compound which exhibited the greatest antitumor efficacy (IC50 = 12.81 μg/ml) contra HepG‐2 carcinoma and Mcf‐7 cells (IC50 = 18.92 ± 0.91 μg/ml). Antimicrobial activity against the strains Klebsiella pneumoniae (K. pneumoniae), Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), Bacillus subtilis (B. subtilis), C. albicans (C. albicans), and Aspergillus niger (A. niger) also gave very promising results when it is compared with the standard drugs. [ABSTRACT FROM AUTHOR]

A.Z. El-Sonbati et al., in their article "Synthesis, characterization of Schiff base metal complexes and their biological investigation" (Appl. Organometal. Chem. 2019, 33, e5048) reported on the synthesis of a new Schiff base named (E)-2-(((3-aminophenyl)imino)methyl)phenol (also known as N-salicylidene-m-phenylenediamine, HL), which was obtained through condensation reaction of m-phenylenediamine and salicylaldehyde in a 1:1 molar ratio. The reported Schiff base HL was involved in the complexation reaction with a series of metal cations named Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II). Although no crystal structures of either the parent ligand HL or its complexes with the mentioned metal cations were reported, the newly synthesized compounds were characterized by means of elemental analysis, IR-, UV-vis- and 1H NMR spectroscopy, mass-spectrometry, magnetic susceptibility, conductivity and thermal analyses. The antimicrobial activity of the discussed compounds, together with the molecular docking results, were also reported. Additionally, both the Schiff base HL and its metallocomplexes were thoroughly examined by quantum chemical calculations. Despite a plethora of different methods being applied to characterize the obtained compounds, herein, I argue that discussion of the results is doubtful. Furthermore, the results of quantum chemical calculations are dubious and must be reconsidered. Although numerous synthetic attempts failed in this work, the hypothetically possible Schiff base HL was revisited using quantum chemical calculations. A.Z. El-Sonbati et al., in their article "Synthesis, characterization of Schiff base metal complexes and their biological investigation" (Appl. Organometal. Chem. 2019, 33, e5048) reported on a new Schiff base (E)-2-(((3-aminophenyl)imino)methyl)phenol (also known as N-salicylidene-m-phenylenediamine, HL) and its metallocomplexes. Herein, I argue that the discussion of the results is doubtful. [ABSTRACT FROM AUTHOR]

Current models for inorganic ion transport in porous media describe the adsorption–desorption processes mostly based on empirical adsorption isotherms or simple thermodynamic mechanisms, often overlooking the adsorption kinetics. This study introduces a novel unified reactive solute transport model framework that incorporates well-established surface complexation models to describe the adsorption–desorption of ions in the transport process and takes into full consideration the non-equilibrium adsorption, enabling the use of the same set of thermodynamic-kinetic parameters to accurately describe ion transport under different chemical conditions. To evaluate the constructed model, Cr(VI), P(V), and As(V) column transport experiments were carried out using goethite-coated sand as the porous medium. Kinetic constants derived from single-ion transport experiments accurately predicted the cotransport behaviors of Cr(VI), P(V), and As(V) under various flow chemistry conditions, especially the overshooting phenomena of Cr(VI) under P(V) and As(V) competition. The model framework can be easily incorporated into solute transport models with various surface complexation reactions to predict the fate and transport of ions under complexed chemical conditions without extensive parameterization, and thus is a useful complement to the current reactive transport model. [ABSTRACT FROM AUTHOR]

Past ocean conditions are often reconstructed using the elemental composition of foraminiferal calcite. However, foraminiferal remains are often impacted by post‐depositional contaminants; thus, they require cleaning prior to element/Ca (El/Ca) analysis. To explore the impact of sample pretreatment on foraminiferal El/Ca ratios (Li, Na, Mg, Al, Mn, Fe, Zn, Sr, I, Ba, and U) we performed six cleaning procedures on four foraminifera populations from distinct depositional environments: Two from South Pacific carbonate ooze (ELT25‐11) and two from the hemi‐pelagic sediments of the California Margin (ODP1017E, SPR0901‐04BC). Despite differences in regional oceanography, sample type (i.e., surface‐ or deep‐dwelling planktic, benthic), and cleaning procedure, the main driver of El/Ca variability in the data set is the sedimentary depositional environment, suggesting site‐specific differences in element concentrations and contaminants. This finding challenges the notion that sample cleaning procedures should be informed by the El/Ca of paleoclimate interest, as elements may be found in different contaminants and/or elemental abundances in unique environments. Our data also show that traditional cleaning methods which use a combination of rinsing, sonication, oxidation/reduction, and complexation reactions effectively remove contaminants found on foraminifera in either depositional environment. However, even after contaminant removal, some elements (i.e., U and Fe) remain higher in California Margin foraminifera relative to South Pacific foraminifera. This suggests that the range of acceptable El/Ca values in the literature must be expanded when working with foraminifera from unusual depositional environments (i.e., hemipelagic, siliciclastic sites with high sedimentation regimes) versus values associated with more typical sites (i.e., a pelagic carbonate ooze). Key Points: Differences in the depositional environment contribute to the greatest variability in the elemental composition of foraminifera samplesThe cleaning procedure steps developed for contaminants in pelagic carbonate oozes are effective in dissimilar depositional environmentsTraditional El/Ca indicators of diagenetic contamination (i.e., Fe, U) may be a primary calcite signal in some depositional environments [ABSTRACT FROM AUTHOR]

Rare-earth elements are widely used in the study of source tracing and geochemical characteristics, which can reflect the degree of influence of human activities on water environment. In order to reveal the additive effects of various human activities on the geochemical characteristics of rare-earth elements in the surface water environment, the content of rare-earth elements in the river in the coal grain composite area of eastern China was determined by inductively coupled plasma mass spectrometry (ICP-MS). The results showed that all water samples were alkaline, ΣREE content ranged 0.18–0.88 μg·L−1, with an average value of 0.28 μg·L−1. All the water samples showed significant enrichment of light rare-earth elements due to a combination of natural processes and external inputs. The spatial distribution and fractionation characteristics of rare-earth elements show that rare-earth elements (especially Ce) are prone to adsorption/complexation reactions with colloidal particles, resulting in their removal from rivers, Eu anomaly is related to plagioclase crystallization and human activities (coal development, agricultural production, urbanization process), and Gd anomaly is only related to human activities. The research results can provide scientific reference for revealing the distribution of rare-earth elements and geochemical environmental behavior in rivers environment under the superimposed influence of various human activities. [ABSTRACT FROM AUTHOR]

In this work, KIT‐6 mesoporous silica material was used to create heterogeneous catalyst due to its excellent surface area, substantial pore volume, and highly functionalized surface. A copper(II) Schiff‐base complex was fabricated on the surface of KIT‐6. For this purpose, (3‐iodopropyl)trimethoxysilane (IPTMS) was synthesized as a linker from (3‐choloropropyl)trimethoxysilane through a simple SN2 reaction using NaI. On the other hand, ligand (a) was synthesized from condensation of diethylenetriamine (DETA) and salicylaldehyde (SA), which was identified by IR and 1H‐NMR techniques. In order to, prepare Sal(PMeOSi)DETA (b), ligand (a) was reacted with IPTMS. One of the challenges of this synthesis was to prove the linkage between the ligand (a) and the IPTMS, which was proved by 1H‐NMR technique. In the next step, the Schiff base complex of copper(Cu(II)[Sal(PMeOSi)DETA]) (c) was synthesized using a complexation reaction of Cu(NO3)2.3 H2O and b. Finally, the obtained copper complex was fixed on KIT‐6, {Cu(II)[Sal(PMeOSi)DETA]} as the new reusable and practical catalyst. This catalyst has been identified using IR, BET, EDS, XRD, SEM, and TGA methods and employed in the synthesis of different tetrazoles for the first time. All tetrazoles were prepared with high yields, and good TOF and TON values, indicating excellent catalytic performance. This catalyst shows excellent homoselectivity in the synthesis of five‐substituted 1H‐tetrazoles. Also, it can be recovered and reused several times without a significant decrease in its catalytic activity or copper leaching. [ABSTRACT FROM AUTHOR]

Four kinds of tridentate [OSO] bisphenol titanium complex catalysts [S (2-CH2-4-tBu-6-R-C6H2O)2]TiCl2(R1 = CMe3, R2 = CPhMe2, R3 = CPh2Me, R4 = CPh3) were prepared from 4-tert-butyl phenol through bromination, nucleophilic substitution and metal complexation reaction by changing the ortho-substituent of hydroxyl. The reaction performance of ethylene polymerization was investigated under the conditions of 30, 50, 70 °C, and pressure of 0.6 MPa. Polyolefin products under different conditions were obtained by changing the Al/Ti ratio of the catalyst and the reaction time. The products were characterized and analyzed by gel chromatogram phy (GPC). The four catalysts under different reaction conditions were compared. Due to the effect of R group steric hindrance, the larger the steric hindrance, the higher the activity of the catalyst. Based on the experimental results, it was concluded that the activity of the [S(2-CH2-4-tBu-6-CMePh2-C6H2O)2]TiCl2 catalyst at 50 °C was up to 6.7 x 106 g PE/(mol Ti ⋅ h), and the obtained polyolefin product Mw was 1.68 x 105, with a molecular weight distribution of 3.2. [ABSTRACT FROM AUTHOR]

2-Chlorobenzaldehyde thiocarbohydrazone (2-CBTCH) is proved as a novel analytical chelating reagent to developa simple, fast and selective liquid–liquid extractive spectrophotometric method for trace level determination of copper(II). The method was based upon the complexation reaction of copper(II) with 2-CBTCH in ethanol. It instantly forms orange coloured [Cu(II)-2 CBTCH] complex at room temperature, which was quantitatively extracted in 1-butanol and shows maximum absorption at 470 nm. The values of molar absorptivity and Sandell's sensitivity of [Cu(II)-2CBTCH] complex are found to be 0.3429 × 104 Lmol−1 cm−1 and 0.01851 µgcm−2, respectively. The system follows Beer's law up to 17.5 µgmL−1. The stoichiometry of the [Cu(II)-2CBTCH] complex in 1-butanol is determined by Job's method, mole ratio method is 1:2 and was confirmed by log-log plot method. To intuit the peak extraction conditions several experimental factors such as pH, reagent concentration, selection of solvent, shaking time, interference of cations and anions has been studiedwell. The usage of masking agent lifts the selectivity of the present method. The method has been effectively used for the determination of copper(II) in alloy samples, pharmaceutical samples, fertiliser samples and environmental samples such as leafy vegetables and water samples. [ABSTRACT FROM AUTHOR]

In this study, we present a facile method for preparing oxidation-resistant Cu nanoparticles through a liquid-phase reduction with imidazole compounds (imidazole, 2-methylimidazole, 2-phenylimidazole, and benzimidazole) that serve as protective and dispersing agents. Through a complexation reaction between Cu atoms, the imidazole compounds can form a protective film on the Cu nanoparticles to prevent the particles from rapidly oxidizing. We compared the effects of the four kinds of imidazole compounds on the oxidation resistance and sintering properties of Cu particles. The Cu particles prepared with benzimidazole could be stored in the air for 30 days without being oxidized. After sintering at 300 °C and 2 MPa, the joint of the particles could reach a shear strength of 32 MPa, which meets the requirements for microelectronic packaging. [ABSTRACT FROM AUTHOR]

Schwertmannite affects the mobility of antimony (Sb) in acid mine drainage, yet the Sb sorption mechanism remains elusive. In this study, the molecular-level mechanism and the driving force of Sb(V) immobilized on schwertmannite were investigated by a combination of wet chemistry, extended X-ray absorption fine structure (EXAFS) analysis, density functional theory (DFT) calculations, and a surface complexation model (SCM). The observed sorption capacity for Sb(V) was as high as 235.63 mg/g. Such remarkable sorption capacity is primarily achieved by the anion exchange reaction and surface complexation reaction of Sb(V) with sulfate and surface/tunnel inner-surface hydroxyl groups, respectively, and the contribution of the anion exchange reaction to Sb(V) immobilization decreases markedly with increasing Sb(V) loading or pH. The loading of Sb(V) appears to be the key parameter controlling its immobilization mechanism on schwertmannite. Low-loaded Sb(V) primarily generates bidentate-mononuclear and bidentate-binuclear surface complexes (adsorption products) and is concurrently partly incorporated into the Fe-O framework of schwertmannite to form a hexadentate-hexanuclear complex (incorporation product). With increasing Sb(V) loading, Sb is primarily adsorbed on the surface and in the tunnel of schwertmannite with the formation of bidentate-mononuclear (dominant) and bidentate-binuclear complexes without incorporation. The inconsistency of the immobilization mechanism is controlled by the amount of released sulfate induced by Sb(V). The substantial system energy reduction caused by the formation of Sb(V) adsorption and incorporation products on the surface and in the tunnel of schwertmannite is the driving force for the stable immobilization of Sb(V) by schwertmannite, and the energy reduction caused by tunnel complexes is far more obvious than that caused by surface complexes. A charge distribution multisite complexation model was established based on bidentate-mononuclear and bidentate-binuclear surface complexes with fitted Log K values of 21.99 ± 0.18 and 12.84 ± 0.92, respectively, which consistently predicted Sb(V) sorption across pH 3.0–9.0 for all involved Sb(V) loadings. In addition, Sb(V) has a strong stabilizing effect on the schwertmannite structure and broadens its pH stability window (pH 3.0–9.0). This study facilitates elucidation of the fate and geochemical cycling of Sb in the mining environment and helps to promote the application of the microstructure of schwertmannite in other studies of microscopic interface chemistry. [ABSTRACT FROM AUTHOR]

A series of C- and B-substituted nido-carborane derivatives with a pendant pyridyl group was prepared. The synthesized compounds were used as ligands in the complexation reactions with bis(triphenylphosphine)nickel(II) and palladium(II) chlorides to give six new metallacomplexes with unusual η5:κ1(N)-coordination of the metal center. The single crystal structures of 1-(NC5H4-2′-S)-1,2-C2B10H11, 1-(NC5H4-2′-CH2S)-1,2-C2B10H11, Cs [7-(NC5H4-2′-CH2S)-7,8-C2B9H11] closo- and nido-carboranes and 3-Ph3P-3-(4(7)-NC5H4-2′-S)-closo-3,1,2-NiC2B9H10 and 3-Ph3P-3-(4(7)-NC5H4-2′-CH2S)-closo-3,1,2-NiC2B9H10 metallacarboranes were determined using single crystal X-ray diffraction. [ABSTRACT FROM AUTHOR]

Phosphino hydrazones represent a versatile class of nitrogen‐containing phosphine ligands. Herein, we report a modular synthesis of phosphino hydrazone ligands by hydrazone condensation reaction of three different aryl hydrazines with 3‐(diphenylphosphino)propanal (PCHO). Complexation reactions of these phosphino hydrazone ligands with palladium(II) and platinum(II) were investigated and the catalytic activity of the palladium(II) complexes was explored in a Cu‐free Sonogashira cross‐coupling reaction achieving yields up to 96 %. Additionally it was shown that the catalytically active species is homogeneous. [ABSTRACT FROM AUTHOR]

To enhance the sorption efficacy of attapulgite for heavy metals, mercapto-functionalized attapulgite (ATP-SH) was synthesized with mercaptan functional groups. When the mass-to-volume ratio of calcined attapulgite (ATP-C) to 3-Mercapropyltrimethoxysilane (MPTMS) was 1 g:0.5 mL (ATP-SH-0.5) and the pH was set to 8, a strong adsorption capacity for Cd (II) and Pb (II) was demonstrated. This indicates excellent adsorption performance for these heavy metals. ATP-SH-0.5 exhibited a maximum adsorption capacity of 43.81 mg/g and 274.83 mg/g for Cd (II) and Pb (II), respectively, in a single ion system. In a binary ion system, the maximum adsorption capacity was 31.86 mg/L and 254.45 mg/L for Cd (II) and Pb (II), respectively. Various characterizations and experiments showed that the adsorption of Cd (II) and Pb (II) onto ATP-SH-0.5 involves ion exchange reactions involving hydroxyl and thiol functional group complexation reactions. This adsorption process follows a single-molecule layer adsorption mechanism. XPS results indicate that hydroxyl and grafted thiol functional groups on the surface of mercapto-functionalized attapulgite participated in surface complexation reactions with Cd (II) and Pb (II), resulting in the formation of Cd-S and Pb-S species. Overall, this study provides a promising mercapto-functionalized modification material for the remediation of polluted water and soil. [ABSTRACT FROM AUTHOR]

New complexes of manganese(II) hexafluoroacetylacetonate [Mn(hfac)2] with 2-(1-R-3-pyrazol-4-yl)-4,4,5,5-tetramethyl-2-imidazoline-3-oxide-1-oxyl (R = CHF2, CH2CH2F, CH2CHF2 or CH2CF3) were synthesised and characterised structurally and magnetically. All complexes were prepared under similar conditions. Nonetheless, their crystal structures were considerably different. Depending on the structure of fluorinated alkyl substituent R, the complexation reaction led to complexes of three types: chain-polymeric complexes with the head-to-head or head-to-tail motif and complexes of molecular structure. All complexes show strong antiferromagnetic behaviour in a high-temperature region (150–300 K) and weak ferro- or antiferromagnetic exchange interactions at low temperatures. The stronger antiferromagnetic exchange, −101.7 ± 1.5 or −136 ± 10 cm−1, −82.3 ± 1.3 cm−1 and −87.4 ± 1.3 cm−1, was attributed to the magnetic interaction in three- or two-spin clusters: {>N∸O–Mn2+–O∸N<} or {>N∸O–Mn2+}, respectively. The weaker antiferromagnetic interaction, −0.005, between three-spin clusters or ferromagnetic interactions, 0.18–0.81 cm−1, between two-spin clusters are realised through the pyrazole ring or intermolecular contacts. [ABSTRACT FROM AUTHOR]

A new cyclam-based ligand bearing two methylene(2,2,2-trifluoroethyl)phosphinate pendant arms was synthesized and its coordination behaviour towards selected divalent transition metal ions [Co(II), Ni(II), Cu(II), Zn(II)] was studied. The ligand was found to be very selective for the Cu(II) ion according to the common Williams–Irving trend. Complexes with all the studied metal ions were structurally characterized. The Cu(II) ion forms two isomeric complexes; the pentacoordinated isomer pc-[Cu(L)] is the kinetic product and the octahedral trans-O,O′-[Cu(L)] isomer is the final (thermodynamic) product of the complexation reaction. Other studied metal ions form octahedral cis-O,O′-[M(L)] complexes. The complexes with paramagnetic metal ions showed a significant shortening of 19F NMR longitudinal relaxation times (T1) to the millisecond range [Ni(II) and Cu(II) complexes] or tens of milliseconds [Co(II) complex] at the temperature and magnetic field relevant for 19F magnetic resonance imaging (MRI). Such a short T1 results from a short distance between the paramagnetic metal ion and the fluorine atoms (∼6.1–6.4 Å). The complexes show high kinetic inertness towards acid-assisted dissociation; in particular, the trans-O,O′-[Cu(L)] complex was found to be extremely inert with a dissociation half-time of 2.8 h in 1 M HCl at 90 °C. Together with the short relaxation time, it potentially enables in vitro/in vivo utilization of the complexes as efficient contrast agents for 19F MRI. [ABSTRACT FROM AUTHOR]

Cyanocobalamin (CNCbl), a medicinal form of vitamin B12, is resistant to glutathione (GSH), and undergoes intracellular processing via reductive decyanation producing the Co(II)-form of Cbl (Cbl(II)) mediated by the CblC-protein. Alteration of the CblC-protein structure might inhibit CNCbl processing. Here, we showed that introducing a bromine atom to the C10-position of the CNCbl corrin ring facilitates its reaction with GSH leading to the formation of Cbl(II) and cyanide dissociation. In a neutral medium, the reaction between C10-Br-CNCbl and GSH proceeds via the complexation of the reactants further leading to dimethylbenzimidazole (DMBI) substitution and electron transfer from GSH to the Co(III)-ion. The reaction is accelerated upon the GSH thiol group deprotonation. The key factors explaining the higher reactivity of C10-Br-CNCbl compared with unmodified CNCbl towards GSH are increasing the electrode potential of CNCbl two-electron reduction upon meso-bromination and the substantial labilization of DMBI, which was shown by comparing their reactions with cyanide and the pKa values of DMBI protonation (pKa base-off). Aquacobalamin (H2OCbl) brominated at the C10-position of the corrin reacts with GSH to give Cbl(II) via GSH complexation and subsequent reaction of this complex with a second GSH molecule, whereas unmodified H2OCbl generates glutathionyl-Cbl, which is resistant to further reduction by GSH. [ABSTRACT FROM AUTHOR]