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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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

• Terrestrial-derived DOM (FA) and autochthonous-derived DOM (B1) inhibit Cd(Ⅱ) sequestration by sediments. • Anthropogenic-derived DOM (SDBS) increased Cd(Ⅱ) sequestration by sediments. • Characterize DOM components based on EEM-PARAFAC. • Characterize the complexation ability between DOM components and Cd(Ⅱ) by complexation reaction models. • Humic-like components significantly inhibit Cd sequestration by sediments. China's lakes are plagued by cadmium (Cd) pollution. Dissolved organic matter (DOM) significantly regulates Cd(II) transport properties at the sediment-water interface. Understanding the effects of different DOM components on the transportation properties of Cd(II) at the sediment-water interface is essential. In this study, typical DOM from different sources was selected to study Cd(II) mobility at the sediment-water interface. Results showed that terrestrial-derived DOM (fulvic acids, FA) and autochthonous-derived DOM (α-amylase, B1) inhibit Cd(II) sequestration by sediments (42.5% and 5.8%, respectively), while anthropogenic-derived DOM (sodium dodecyl benzene sulfonate, SDBS) increased the Cd(II) adsorption capacity by sediments by 2.8%. Fluorescence quenching coupling with parallel factor analysis (EEM-PARAFAC) was used to characterize different DOM components. The results showed that FA contains three kinds of components (C1, C3: protein-like components, C2: humic-like components); SDBS contains two kinds of components (C1, C2: protein-like components); B1 contains three kinds of components (C1, C2: protein-like components, C3: humic-like components).Three complex reaction models were used to characterize the ability of Cd(II) complex with DOM, and it was found that the humic-like component could hardly be complex with Cd(II). Accordingly, humic-like components compete for Cd(II) adsorption sites on the sediment surface and inhibit Cd(II) adsorption from sediments. Fourier transform infrared spectroscopy (FTIR) of the sediment surface before and after Cd(II) addition was analyzed and proved the competitive adsorption theory. This study provides a better understanding of the Cd(II) mobilization behavior at the sediment-water interface and indicates that the input of humic-like DOM will increase the bioavailability of Cd. [Display omitted] [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]

Some seriously weathered jades of Fubin culture were unearthed at the Moyishan site in Lingnan, South China. These long-buried jades have many secondary changes such as discoloration, microstructural change and chemical composition variation. To explore the formation mechanism of secondary changes, the microstructure, mineral components, and chemical content of the jade samples and their buried soil are analyzed separately. The jade with red-brown shell is preserved well and shows better structural stability, further research indicates that it's the result of surface complexation reactions. During the long-term burial in acidic soil environment, the jade wrapped in the negatively charged kaolinite which absorbed Fe3+ to complexed on the jade surface. Iron(ⅲ) precipitates causes the dense shell to appear red-brown. [ABSTRACT FROM AUTHOR]

• The sorption behaviour of ROX on ferrihydrite has been systematically investigated. • H-bonding and surface complexation reactions are the main mechanisms that control the sorption of ROX. • The 2D-COS analysis revealed that substituents were involved in the dynamic binding process. • The H-bonding reaction takes precedence over surface complexation and is more susceptible to external interference. • More substituents were altering the sorption process of phenylarsonic compounds. The retention and fate of Roxarsone (ROX) onto typical reactive soil minerals were crucial for evaluating its potential environmental risk. However, the behavior and molecular-level reaction mechanism of ROX and its substituents with iron (hydr)oxides remains unclear. Herein, the binding behavior of ROX on ferrihydrite (Fh) was investigated through batch experiments and in-situ ATR-FTIR techniques. Our results demonstrated that Fh is an effective geo-sorbent for the retention of ROX. The pseudo-second-order kinetic and the Langmuir model successfully described the sorption process. The driving force for the binding of ROX on Fh was ascribed to the chemical adsorption, and the rate-limiting step is simultaneously dominated by intraparticle and film diffusion. Isotherms results revealed that the sorption of ROX onto Fh appeared in uniformly distributed monolayer adsorption sites. The two-dimensional correlation spectroscopy and XPS results implied that the nitro, hydroxyl, and arsenate moiety of ROX molecules have participated in binding ROX onto Fh, signifying that the predominated mechanisms were attributed to the hydrogen bonding and surface complexation. Our results can help to better understand the ROX-mineral interactions at the molecular level and lay the foundation for exploring the degradation, transformation, and remediation technologies of ROX and structural analog pollutants in the environment. [Display omitted] [ABSTRACT FROM AUTHOR]

Octadecylamine（ODA） is a commonly used collector in the production of potassium chloride by positive flotation. For control and optimization of the production process of high-purity potassium salt products, it is essential to rapidly and precisely determine the amount of ODA in the sample at the flotation stage. According to the complexation reaction between ODA and methyl orange in a weak acidic environment, the concentration of ODA in the solution was obtained by measuring the absorbance of the remaining methyl orange at a specific wavelength, and a spectrophotometric method for rapid determination of the concentration of ODA in salt solution was established. The determination wavelength is 463 nm, the linear correlation equation is A=-0.086 56c+2.517 26, the linear correlation coefficient（R²） is 0.993 46, the detection limit is 0.048 mg/L, and the relative standard deviation（RSD） is 0.148%～0.297%. The analysis and testing of the slurry obtained in different sections of potassium fertilizer flotation indicate that the recovery rate of spiking is between 99.65% and 104.06%. This method benefits from the simple operation, high sensitivity, fast detection, and low cost. It can be used to determine the concentration of ODA in aqueous solutions, positive flotation process, and potassium salt products without the usage of a large amount of organic reagents during the analytical procedure. [ABSTRACT FROM AUTHOR]

To investigate the synergistic catalytic effects of boric acid and α-hydroxycarboxylic acids (HCAs), we analyzed and measured the effects of the complexation reactions between boric acid and HCAs on the ionization equilibrium of the HCAs. Eight HCAs, glycolic acid, D-(−)-lactic acid, (R)-(−)-mandelic acid, D-gluconic acid, L-(−)-malic acid, L-(+)-tartaric acid, D-(−)-tartaric acid, and citric acid, were selected to measure the pH changes in aqueous HCA solutions after adding boric acid. The results showed that the pH values of the aqueous HCA solutions gradually decreased with an increase in the boric acid molar ratio, and the acidity coefficients when boric acid formed double-ligand complexes with HCAs were smaller than those of the single-ligand complexes. The more hydroxyl groups the HCA contained, the more types of complexes could be formed, and the greater the rate of change in the pH. The total rates of change in the pH of the HCA solutions were in the following order: citric acid > L-(−)-tartaric acid = D-(−)-tartaric acid > D-gluconic acid > (R)-(−)-mandelic acid > L-(−)-malic acid > D-(−)-lactic acid > glycolic acid. The composite catalyst of boric acid and tartaric acid had a high catalytic activity—the yield of methyl palmitate was 98%. After the reaction, the catalyst and methanol could be separated by standing stratification. [ABSTRACT FROM AUTHOR]

A new sustainable heterogeneous catalyst for copper-catalyzed azide-alkyne cycloaddition reaction (CuAAC) was investigated. The preparation of the sustainable catalyst was carried out through the complexation reaction between the polysaccharide cellulose acetate backbone (CA) and copper(II) ions. The resulting complex [Cu(II)-CA] was fully characterized by using different spectroscopic methods such as Fourier-transform infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX), Ultraviolet-visible (UV-vis), and Inductively Coupled Plasma (ICP) analyses. The Cu(II)-CA complex exhibits high activity in the CuAAC reaction for substituted alkynes and organic azides, leading to a selective synthesis of the corresponding 1,4-isomer 1,2,3-triazoles in water as a solvent and working at room temperature. It is worth noting that this catalyst has several advantages from the sustainable chemistry point of view including no use of additives, biopolymer support, reactions carried out in water at room temperature, and easy recovery of the catalyst. These characteristics make it a potential candidate not only for the CuAAC reaction but also for other catalytic organic reactions. [ABSTRACT FROM AUTHOR]

The complexation of 5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrin and 5,10,15,20-tetrakis(2,6-difluorophenyl)porphyrin and metal exchange reactions of their cadmium complexes with manganese(II) chloride in DMF were studied with the goal of finding optimal conditions for the synthesis of manganese(II) and manganese(III) complexes with tetrapyrrole macrocyclic compounds. ortho-Substituted manganese com-plexes were synthesized by prolonged heating of the corresponding porphyrins with excess MnCl2 in boiling DMF. Metal exchange reactions of cadmium(II) 5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrin and cadmium(II) 5,10,15,20-tetrakis(2,6-difluorophenyl)porphyrin with MnCl2 in DMF produced the corresponding manganese(III) tetraphenylporphyrins. In contrast, the complexation of tetraphenylporphyrins substituted at both pyrrole and phenyl rings with manganese(II) chloride in DMF under mild conditions afforded manga-nese(II) 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrin, which was oxidized to a mixture of manganese(II) and manganese(III) porphyrins on exposure to air, and manganese(II) 2,3,7,8,12,13,17,18-octachloro-5,10,15,20-tetrakis(2,6-difluorophenyl)porphyrin. The synthesized compounds were identified by electronic absorption spectroscopy, 1H NMR, and mass spectrometry. The metal exchange reactions of ortho-substituted cadmium(II) tetraphenylporphyrins and the complexation of 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrin with manganese(II) chloride in DMF were studied by spectrophotometry, and their kinetic and activation parameters were determined. A significant effect of β- and ortho-substitution on the complexation and metal exchange reactions was revealed. [ABSTRACT FROM AUTHOR]

Here, we describe the recent progress on metal‐coordinated supramolecular structures with unique characteristics and controlled helicity based on coordination geometry and dynamic intermolecular binding events. The current major research area is the self‐assembly of a metal‐containing molecule into nanomaterials. It generated a large number of supramolecular polymers, which have various structures and functions. Although the dynamic coordination complexation reactions between various metal ions and ligands are spontaneous, we successfully achieved unique morphological transformations with helical inversion of metal‐containing supramolecular polymers via the kinetic control of dynamic coordination complexation reactions. Our findings have a significant impact on the development of novel and advanced supramolecular materials, and dynamic coordination bonds in the molecular design of metal‐containing complexes for modulating self‐assembly pathways, which may be relevant for the fabrication of supramolecular materials with interesting properties. Our contributions may be useful to the understanding of chiral assembly processes in biological systems. [ABSTRACT FROM AUTHOR]

[Display omitted] The high binding affinity of iron(oxyhydr)oxides for phosphate has recently been used in medicine to treat hyperphosphatemia, an abnormally elevated phosphate concentration in the blood. For iron(oxyhydr)oxide nanoparticles, the composition of the organic shell has a more significant influence on their interaction with phosphate than is often assumed. This study shows different mechanisms in phosphate binding, using the example of two similar new phosphate-binding agents. We characterized the phosphate-binding behavior of two iron(oxyhydr)oxide-based nanomaterials with similar composition and particle properties and investigated their binding mechanisms by spectroscopic methods. For the often prescribed Velphoro, we demonstrated a phosphate binding capacity of>210 mg/g. A similar active ingredient named C–PAM binds over 573 mg/g. Spectroscopic measurements highlighted differences in the binding mechanism. While Velphoro binds phosphate via surface complexation independent of pH and adsorbent concentration, C–PAM shows a strong concentration dependence. At low concentrations, phosphate is bound via complexation reactions. The iron(oxyhydr)oxide structure was dissolved at higher phosphate concentrations and formed various iron phosphate species. The substances behave differently upon interaction with phosphate, although being very similar in composition and crystal structure. Thus, we demonstrated a crucial influence of the ligands in the shell on the binding mechanism. [ABSTRACT FROM AUTHOR]

In this work, we explored coordination compounds featuring caffeine‐based carbene co‐ligands and tridentate dianionic pincer luminophores derived from 2,6‐bis(1H‐1,2,4‐triazol‐5‐yl)pyridine (N), as well as from 2‐phenyl‐6‐(1H‐1,2,4‐triazol‐5‐yl)pyridine (C), bearing either Ad (adamantyl) or tBu (tertiary butyl) substituents. The new 2‐phenyl‐6‐(1H‐1,2,4‐triazol‐5‐yl)pyridine‐based ligand precursors along with four Pt(II) complexes, namely Pt(C‐tBu), Pt(C‐Ad), Pt(N‐tBu) and Pt(N‐Ad) were characterized. Further on, the influence of the different substituents at the chelating luminophores and of the caffeine‐based NHC‐co‐ligand on the photophysical properties (including photoluminescence quantum yields (ΦL), excited‐state lifetimes (τ), radiative (kr), and non‐radiative (knr) deactivation rate constants) was assessed in fluid solutions at room temperature (RT) and in frozen glassy matrices at 77 K. All four luminophores perform equivalently well within the experimental uncertainty. In deoxygenated fluid solutions at RT, photoluminescence quantum yields reaching up to 24 ± 2% and excited‐state lifetimes of around 12 μs were found. The generally long excited‐state lifetimes and only minor blue shift upon cooling to 77 K along with mostly well‐resolved vibrational progressions point to metal‐perturbed ligand‐centered excited states. Notably, the yield of the complexation reaction in case of Pt(C‐tBu) and Pt(C‐Ad) was almost two times higher compared to Pt(N‐tBu) and Pt(N‐Ad). Cyclometallation is not an essential feature to achieve high photoluminescence quantum yields, but it can improve the synthetic efficiency. In summary, it can be observed that coordination chemical concepts based on natural products can lead to stable phosphorescent species with interesting excited‐state properties. [ABSTRACT FROM AUTHOR]

This work concerns the study of the extraction of copper (II) in the perchlorate medium by Bis‐2‐ethylhexyl phosphoric acid (D2EHPA) in methyl isobutyl ketone (MIBK) at 25 °C at different ionic strength (1, 1/6, 1/10 mol kg−1). The stoichiometry of the reaction of extracted complexations was determined by the slope method. The organometallic complexes extracted in the organic phase are of the type CuL2 in methyl isobutyl ketone has unit ionic strength. The organometallic complexes extracted in the organic phase are of the type CuL2ClO4(H2O) or CuL2ClO4 (MIBK)x in methyl isobutyl ketone has different ionic strength Efficiency of the extraction of copper (II) depends on the ionic strength of the aqueous medium. Hence when the ionic strength of the aqueous perchlorate medium increases the extraction of copper (II) increases. [ABSTRACT FROM AUTHOR]

This study was conducted to ascertain the effect of heavy metals on the general quality of borewell water in a municipality near Kollam District, Kerala state, India. Red-water iron contamination in borewell water has been a major concern for many years that has not been fully resolved. This research introduces an innovative, reliable, and efficient organoclay scavenger for the adsorptive removal of Fe(III) ions from watersheds, by grafting MBO onto Na-MMT clay (MBO/Na-MMT), which was produced via one-pot oxidation reaction using H 2 O 2 to introduce the active functional groups, like the -SOH group, onto the montmorillonite clay. This special alteration of this material improved Na-MMT's capacity to adsorb ferric ions. To evaluate the material's characteristics, X-ray diffraction, SEM-EDS, FTIR, CHNS, TG, and Zeta potential were used. Batch adsorption tests with different solution pH, Fe(III) ion concentrations, agitation periods, adsorbent dose and temperatures were conducted in order to optimise the adsorption procedure. The MBO/Na-MMT exceeded several of the reported adsorbent materials in the literature with an impressive adsorption capacity of 83.33 mg/g and efficiency (97.9%), which was accomplished by spontaneous complexation reaction. Fe(III) spontaneously attached to MBO/Na-MMT by a complex formation reaction mechanism with PSO kinetics and the variability of the adsorption process was highlighted by Elovich kinetic model because of heterogeneity of the surface. The adsorbent material demonstrated a remarkable capability for regeneration, ensuring the material's stability and reusability. [Display omitted] • The adsorption capacity of MBO/Na-MMT for Fe(III) ions was examined. • Fe(III) ion enhanced adsorption capacity of 83.33 mg/g was attained. • A SN2 Mechanism is used in one-pot oxidation to activate chemicals. • FTIR, XRD, SEM, and pH experiments were used to suggest the mechanism of Fe(III) ion binding. • Excellent material reusability for adsorption. [ABSTRACT FROM AUTHOR]

In order to realize the resource utilization of agricultural waste waste fungus sticks (EF), KM-n04 and CuCl2 ⋅ 2H2O were used to modify EF biochar (EFBC) prepared at low temperature to prepare copper-manganese modified EFBC (Cu-Mn-EFBC). SEM, BET, XRD, FTIR, Zeta potential and EA characterization were carried out, and the effects of preparation and reaction conditions on the adsorption of tetracycline hydrochloride (TCH) in water by Cu-Mn-EFBC were investigated and the mechanism was analyzed. The results showed that the removal rate of TCH by Cu-Mn-EFBC was 90. 03%, which was much higher than that of EFBC (21.44% ), the dosage of biochar and ionic strength had little effect on the adsorption, and the pH value of the solution has a great influence; the pseudo-second-order kinetic equation and the Freundlich equation can better fit the adsorption process. The adsorption mechanism is mainly cation-π interaction, π- π interaction, hydrogen bonding and complexation reaction. [ABSTRACT FROM AUTHOR]

Triazine derivatives have attracted increasing attention due to their diverse applications in medicinal chemistry. They have been reported to be remarkably effective compounds regarding their bioactivities. Therefore, the synthesis and identification of new triazine-derived compounds are of interest for their therapeutic effects. Various approaches have been developed to synthesize triazine derivatives. In this review, a considerable number of studies on the synthesis of 1,2,4-triazine derivatives are investigated with 4-amino-3-thioxo-6-substituted-1,2,4-triazin-ones and 4-amino-3-hydrazino-6-substituted-1,2,4-triazin-5-ones as starting materials. Different types of chemical reactions have been applied to the efficient synthesis of 3-thioxo/hydrazino-6-substituted-1,2,4-triazin-5-ones, such as alkylation, acylation, aroylation, elimination, substitution, acidic/basic hydrolysis, oxidation, cyclocondensation, cycloaddition, phosphorylation, and complexation reactions. Interestingly, a set of compounds is identified to possess various biological activities, such as anticancer antibacterial, antifungal, acaricidal, and molluscicidal properties. Also, some 4-amino-3-thioxo-6-substituted-1,2,4-triazin-5-one derivatives are found to form metal complexes, be used as inhibitor probes for mild steel corrosion, prepare a selective sensor for the determination of gadolinium (III) ions in the soil and sediment samples, and demonstrate antibacterial activities. Finally, 4-amino-3-hydrazino-6-methyl-1,2,4-triazin-5-one was used as an ionophore to develop a chromium (III) ion-selective sensor beside the formation of silver complexes. [ABSTRACT FROM AUTHOR]

[Display omitted] Nanoscale zero-valent iron (nZVI)-based composites have been widely utilized in environmental cleanup due to their low cost, high adsorption performance and strong redox activity. Herein, removal mechanism of U(VI) on nZVI/clay composites was demonstrated by batch, XPS and modeling techniques. The batch experiments showed that nZVI/clay composites exhibited the high removal capacity (88.90 mg/g at pH 4.0) and good regeneration towards U(VI) from aqueous solution. The adsorbed U(VI) was mostly reduced to U(IV) by nZVI/clay composites according to XPS analysis. The removal process of U(VI) on nZVI/clay composites was satisfactorily fitted by surface complexation modeling using strong and weak sites, indicating the high chemisorption of U(VI) on nZVI/clay composites. However, the fitting results underestimated U(VI) adsorption at pH 7.0–9.0 due to the reduction of U(VI) into U(IV), whereas the overestimation of U(VI) at pH 4.0–6.0 could be attributed to fewer surface complexation reaction involved. These findings are crucial for the application of nZVI-based composites for the highly efficient removal of radionuclides in actual environmental remediation. [ABSTRACT FROM AUTHOR]

[Display omitted] Nanoscale zero-valent iron (nZVI)-based composites have been widely utilized in environmental cleanup due to their low cost, high adsorption performance and strong redox activity. Herein, removal mechanism of U(VI) on nZVI/clay composites was demonstrated by batch, XPS and modeling techniques. The batch experiments showed that nZVI/clay composites exhibited the high removal capacity (88.90 mg/g at pH 4.0) and good regeneration towards U(VI) from aqueous solution. The adsorbed U(VI) was mostly reduced to U(IV) by nZVI/clay composites according to XPS analysis. The removal process of U(VI) on nZVI/clay composites was satisfactorily fitted by surface complexation modeling using strong and weak sites, indicating the high chemisorption of U(VI) on nZVI/clay composites. However, the fitting results underestimated U(VI) adsorption at pH 7.0–9.0 due to the reduction of U(VI) into U(IV), whereas the overestimation of U(VI) at pH 4.0–6.0 could be attributed to fewer surface complexation reaction involved. These findings are crucial for the application of nZVI-based composites for the highly efficient removal of radionuclides in actual environmental remediation. [ABSTRACT FROM AUTHOR]