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Abstract To obtain high efficient elimination of ammonia (NH4 +) from wastewater, Cu(II), Ni(II), and Co(II)) were loaded on Dowex-50WX8 resin (D-H) and studied their removal efficiency towards NH4 + from aqueous solutions. The adsorption capacity of Cu(II)-loaded on D-H (D-Cu2+) towards NH4 + (qe = 95.58 mg/g) was the highest one compared with that of D-Ni2+ (qe = 57.29 mg/g) and D-Co2+ (qe = 43.43 mg/g). Detailed studies focused on the removal of NH4 + utilizing D-Cu2+ were accomplished under various experimental conditions. The pseudo-second-order kinetic model fitted well the adsorption data of NH4 + on D-Cu2+. The non-linear Langmuir model was the best model for the adsorption process, producing a maximum equilibrium adsorption capacity (qmax = 280.9 mg/g) at pH = 8.4, and 303 K in less than 20 min. The adsorption of NH4 + onto D-Cu2+ was an exothermic and spontaneous process. In a sustainable step, the resulting D-Cu(II)-ammine composite from the NH4 + adsorption process displayed excellent catalytic activity for the degradation of aniline blue (AB) and methyl violet 2B (MV 2B) dyes utilizing H2O2 as an eco-friendly oxidant.

Molecular targets for a promising antitumor agent based on trans-stilbene containing a pyridoxine fragment were identified. The lead compound, (E)-6-(3,4-dimethoxystyryl)-2,2,5,8-tetramethyl-4H-[1,3] dioxino[4,5-c]pyridine, was found to selectively induce apoptosis in MCF-7 breast adenocarcinoma cells overexpressing estrogen receptor, but not in MDA-MB-231 cells negative for estrogen receptor. The mechanism by which the novel trans-stilbene derivative acts as a selective estrogen receptor modulator was analyzed, and the affinity for human estrogen receptor α (ERα) was assessed by fluorescence polarization. Unlike its structural analogs—tamoxifen and raloxifene, the lead compound showed no affinity for ERα and did not form complexes with it. Therefore, it was concluded that the selective action of the pyridoxine-containing derivative of trans-stilbene on estrogen-positive breast cancer cells occurs through an alternative mechanism. The EC50 values for the displacement of the fluorescent ligand from the ERα active site were 22, 120, and 595 nM for estradiol, raloxifene, and tamoxifen, respectively.

We have been working with carbon nanotube separation through host–guest chemistry. Herein, a new macrocyclic host molecule, Cu-tethered square nanobrackets, is designed, synthesized and applied to single-walled carbon nanotubes (SWNTs) for their diameter-based separation. The complexation between copper ions and dipyrrin moieties of the nanobracket gives Cu-tethered square nanobrackets, which is confirmed by absorption, Raman and MALDI-TOF mass spectra. Upon extraction of SWNTs with the nanobracket and copper(II), in situ-formed square Cu-nanobrackets are found to interlock SWNTs to disperse them in 2-propanol. The interlocking is confirmed by Raman spectroscopy after thorough washing of the extracted SWNTs. Pristine SWNTs were recovered through demetalation of the interlocked ones along with the nanobracket. Raman and absorption spectroscopies of the extracted SWNTs reveals the diameter enrichment of only several kinds of SWNTs in the diameter range from 0.94 to 1.10 nm among ≈20 kinds of SWNTs from 0.76 to 1.20 nm in their diameter range. The diameter selectivity is supported by the theoretical calculations with the GFN2-xTB method, indicating that the most preferred SWNT diameter for the square Cu-nanobrackets is 1.04 nm.

To obtain high efficient elimination of ammonia (NH4+) from wastewater, Cu(II), Ni(II), and Co(II)) were loaded on Dowex-50WX8 resin (D-H) and studied their removal efficiency towards NH4+ from aqueous solutions. The adsorption capacity of Cu(II)-loaded on D-H (D-Cu2+) towards NH4+ (qe = 95.58 mg/g) was the highest one compared with that of D-Ni2+ (qe = 57.29 mg/g) and D-Co2+ (qe = 43.43 mg/g). Detailed studies focused on the removal of NH4+ utilizing D-Cu2+ were accomplished under various experimental conditions. The pseudo-second-order kinetic model fitted well the adsorption data of NH4+ on D-Cu2+. The non-linear Langmuir model was the best model for the adsorption process, producing a maximum equilibrium adsorption capacity (qmax = 280.9 mg/g) at pH = 8.4, and 303 K in less than 20 min. The adsorption of NH4+ onto D-Cu2+ was an exothermic and spontaneous process. In a sustainable step, the resulting D-Cu(II)-ammine composite from the NH4+ adsorption process displayed excellent catalytic activity for the degradation of aniline blue (AB) and methyl violet 2B (MV 2B) dyes utilizing H2O2 as an eco-friendly oxidant. [ABSTRACT FROM AUTHOR]

Research on the recovery of rare earth elements from wastewater has attracted increasing attention. Compared with other methods, biosorption is a simple, efficient, and environmentally friendly method for rare earth wastewater treatment, which has greater prospects for development. The objective of this study was to investigate the biosorption behavior and mechanism of Yarrowia lipolytica for five rare earth ions (La3⁺, Nd3⁺, Er3⁺, Y3⁺, and Sm3⁺) with a particular focus on biosorption behavior, biosorption kinetics, and biosorption isotherm. It was demonstrated that the biosorption capacity of Y. lipolytica at optimal conditions was 76.80 mg/g. It was discovered that the biosorption process complied with the pseudo-second-order kinetic model and the Langmuir biosorption isotherm, indicating that Y. lipolytica employed a monolayer chemical biosorption process to biosorb rare earth ions. Characterization analysis demonstrated that the primary functional groups involved in rare earth ion biosorption were amino, carboxyl, and hydroxyl groups. The cooperative biosorption of rare earth ions by Y. lipolytica was facilitated by means of surface complexation, ion exchange, and electrostatic interactions. These findings suggest that Y. lipolytica has the potential to be an effective biosorbent for the removal of rare earth elements from wastewater. [ABSTRACT FROM AUTHOR]

CO2 mineral carbonation is an important method to sequester carbon dioxide (CO2) in the form of stable mineral carbonates for permanent storage. The slow kinetics of carbonation, especially for iron-rich olivine, is the major challenge for potential application. This work proposes methods to accelerate the mineral carbonation process of different materials in the general mineral grouping of divalent metals–olivine for simultaneous nickel and cobalt recovery. It is found that nickel-olivine is facile for mineral carbonation compared to ferrous and magnesium olivine. Ferrous olivine is the most difficult form of olivine to carbonate as illustrated in both thermodynamics and experimental test results. The increase in iron content in olivine inhibits the CO2 mineral carbonation process by forming an iron-silica-rich passivation interlayer. The use of a reducing gas or reagent can enhance the mineral carbonation of olivine probably through hindering oxidation of Fe(Ⅱ). The addition of sodium nitrilotriacetate (NTA) as a metal complexing agent is much more efficient for the acceleration than usage of a reducing atmosphere. The combination of sodium bicarbonate/CO2 gas supply and NTA can enhance the diffusion of all divalent metal ions from the reacting olivine surface, thereby limiting the formation of the passivation interlayer. Meanwhile, highly selective nickel and cobalt leaching can be simultaneously achieved along with the CO2 mineral carbonation, 94% nickel, and 92% cobalt leaching as well as 47% mineral carbonation versus only 10% iron and 1% magnesium leached in 2 h. This work provides a novel direction to achieve critical metals recovery with accelerated mineral carbonation process. [ABSTRACT FROM AUTHOR]

The 3-diethylaminophenol (3-DEAP) incorporated anthraquinone mono-azo dye derivative [(E)-1-((4-(diethylamino)-2-hydroxyphenyl)diazenyl)anthracene-9,10-dione] DAAD was synthesized through an electrophilic substitution reaction. The interaction between the -OH functional group and the nitrogen atom of the azo moiety may result in intramolecular proton transfer in the DAAD. DAAD was treated with metal ions such as Co(II), Ni(II), and Cu(II) acetates in a ratio of 2 : 1 revealing an octahedral structure. Many analytical and spectroscopic methods, including UV-vis, FT-IR, (1H and 13C) NMR, HRMS, TGA, VSM, ESR, and powder XRD methods, were used to verify the structural characteristics of the compounds. Additionally, the potency of the in-vitro antioxidant properties of the ligand and its Cu(II), Ni(II), and Co(II) complexes were evaluated; the results revealed that the Co(II) complex showed a maximum percent inhibition of 85 μM against the standard ascorbic acid. [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]

The studies showed the effectiveness of green-synthesized SiO2NPs in mitigating the toxicity of Arsenic. Density Functional Theory (DFT) is a computational method used to determine electronic structure, energy gap, and toxicity prediction. Experimentally, silicon nanoparticles of 0 (S0) and 100% v/v (S100) were applied to the surface of the soil. 150 mL of Arsenic trioxide was applied twice at a rate of 0 (As0) and 3.2 g/mL (As3.2) at an interval of three weeks. Green synthesized SiO2NPs possessed a higher chemical potential (µ) and electrophilicity index; consequently, charges could be transferred and easily polarized. The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels of the green synthesized SiO2NPs enable them to donate electrons and complex with arsenic, reducing their bioavailability and toxicity. Evidence from the studies further showed that SiO2NPs had buffered the soil acidity and electric conductivity, posing a high binding site and reactivity with exchangeable cations and micronutrients due to their smaller energy gap. Furthermore, the catalytic activities of the soil enzymes dehydrogenase (DHA) and peroxidase (POD) were greatly increased, which enhanced the electrostatic interaction between the SiO2NPs and As. [ABSTRACT FROM AUTHOR]

In this study, three hydration heat controlling materials (HHCMs), respectively, containing pure hydroxyl (polyvinyl alcohol, PVA), carboxylic (polyacrylic acid, PAA) and ester groups (maleic acid-ethylene glycol ester, P(MA-EG)) were synthesized and mixed with cement-based materials, and the hydration heat and setting time of cement pastes and the SEMI adiabatic temperature rise and strength of mortars were tested. The results showed that PAA and P(MA-EG) reduced the peak value of hydration exothermic rate by 77.45% and 62.28%, respectively, and prolonged 54.14 h and 15.56 h, respectively. Mechanism studies showed that HHCMs containing carboxylic or hydroxyl groups adsorbed on cement particles by Ca2+ complexation, while HHCMs containing ester groups hydrolyzed to carboxylic groups in alkaline cement pastes, which hydrolysis rate changed with the hydration temperature of cement-based materials to regulate the hydration process. This study aims to provide technical feasibility and theoretical basis for exploring new avenues of synthesizing HHCMs with different functional groups. [ABSTRACT FROM AUTHOR]

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Thiophene, a heterocyclic compound characterized by a five-membered ring comprising four carbon atoms and one sulfur atom, has garnered significant attention in recent research due to its versatile applications in medicinal and chemosensing fields. Thiophene derivatives formed complexes with various transition metals. These complexes exhibit promising anti-inflammatory, anticancer, antibacterial, antifungal and other biological properties. Certainly, the complexation phenomenon involving thiophene derivatives can be effectively used for the recognition of various cations. Thiophene-based compounds can act as selective ligands, forming stable complexes with specific heavy metal ions. This property has significant implications for environmental monitoring, industrial safety, and public health, as the presence of heavy metal ions beyond permissible levels can lead to detrimental effects. This paper explored the versatile applications of thiophene derivatives, investigating their chemosensing potential for the determination of various metal ions covering the period from 2018 to 2024. Thiophene derivatives serve as versatile ligands for metal ions and exhibit fluorescence and colorimetric changes for selective detection of metal ions. Additionally, this study also explores the anticancer efficacy demonstrated by metal complexes derived from thiophene, with a specific emphasis on those formed with platinum-group metals (Ir(III), Ru(II), Ru(III), Rh, Os(II), Os(IV), Pd(II), Pt(II)). [ABSTRACT FROM AUTHOR]

Heavy metals such as Iron, Copper, and Zinc are micro-essential trace metal and involve animportant biological role, but it quickly turns toxic at exceeding the permissible limit, causing gastrointestinal irritation, liver, bone, and kidney damage, as well as disorders including Wilson's, Parkinson's, and Alzheimer's. It is important to detect the metal ions as well as their concentration quickly and affordable cost using organic probes. Among the organic probes,the coumarin fluorescent probe shows a very prominent candidate with heavy metal ions. Therefore, in the present review, we reviewed the very recent literature the identify the heavy metals using modified coumarin fluorescent probes. Readers will get information quickly about the method of preparation of modified coumarin core and their use as fluorescent probes with heavy metals using absorption and emission spectroscopic methods along with the probable mechanistic pathway of detection. [ABSTRACT FROM AUTHOR]

The ongoing development of bacterial resistance to antibiotics is a global challenge. Research in that field is thus necessary. Analytical techniques are required for such a purpose. From this perspective, the focus was on atomic absorption spectrometry (AAS). Although it is old, AAS often offers unexpected potential. Of course, this should be exploited. The aim was therefore to demonstrate the versatility of the technique in antibacterial research. This is illustrated by various examples of its practical application. AAS can be used, for example, to confirm the identity of antibacterial compounds, for purity controls, or to quantify the antibiotics in pharmaceutical preparations. The latter allowed analysis without laborious sample preparation and without interference from other excipients. In addition, AAS can help elucidate the mode of action or resistance mechanisms. In this context, quantifying the accumulation of the antibiotic drug in the cell of (resistant) bacteria appears to play an important role. The general application of AAS is not limited to metal-containing drugs, but also enables the determination of some organic chemical antibiotics. Altogether, this perspective presents a range of applications for AAS in antibacterial research, intending to raise awareness of the method and may thus contribute to the fight against resistance. [ABSTRACT FROM AUTHOR]

In this work, complexes formed by sodium caseinate (NaCn) and xanthan gum (XG) were tested as novel natural stabilizers. They were prepared at pH 4, using a constant concentration of XG (0.4%) and different NaCn concentrations. Then, they were characterized in terms of turbidity, surface tension (ST), and rheology. The acquired results indicated that the ST of NaCn solution and NaCn/XG dispersion decreases with NaCn concentration. In addition, the ST of NaCn/XG is higher than that of NaCn solution indicating interactions between NaCn and XG. In addition, the turbidity of the dispersions increases while ST decreases with NaCn concentration. Fourier transform spectroscopy (FTIR) spectra confirmed the formation of a complex between NaCn and XG through electrostatic interactions. Structural analyses demonstrated that the morphologies of the complex particles are different compared to the pure biopolymer ones. Furthermore, the oil‐in‐water (O/W) emulsions based on NaCn/XG complexes formed into acid conditions were studied. The obtained results showed that the stability, the average diameter of the droplets, and the rheological behavior of the formulated emulsions depend on the NaCn:XG ratio. Emulsion formulated with 0.5:1, 1:1, 1.5:1, 2:1 NaCn:XG ratio presented good creaming stability during 1 month of storage at 25°C. On the other hand, samples formulated with a 1:1 ratio of NaCn/XG exhibited the best stability. Their average diameter (29.026 μm) remained constant during the storage. Emulsions formulated with higher ration PR:PS (2.5:1, 3:1) were unstable and have larger droplets. Also, all formulations showed a shear‐thinning and elastic behavior. [ABSTRACT FROM AUTHOR]

Aquatic humic substances (AHS) are defined as an important components of organic matter, being composed as small molecules in a supramolecular structure and can interact with metallic ions, thereby altering the bioavailability of these species. To better understand this behavior, AHS were extracted and characterized from Negro River, located near Manaus city and Carú River, that is situated in Itacoatiara city, an area experiencing increasing anthropogenic actions; both were characterized as blackwater rivers. The AHS were characterized by 13C nuclear magnetic ressonance and thermochemolysis GC–MS to obtain structural characteristics. Interaction studies with Cu (II), Al (III), and Fe (III) were investigated using fluorescence spectroscopy applied to parallel factor analysis (PARAFAC) and two-dimensional correlation spectroscopy with Fourier transform infrared spectroscopy (2D-COS FTIR). The AHS from dry season had more aromatic fractions not derived from lignin and had higher content of alkyls moities from microbial sources and vegetal tissues of autochthonous origin, while AHS isolated in the rainy season showed more metals in its molecular architecture, lignin units, and polysacharide structures. The study showed that AHS composition from rainy season were able to interact with Al (III), Fe (III), and Cu (II). Two fluorescent components were identified as responsible for interaction: C1 (blue-shifted) and C2 (red-shifted). C1 showed higher complexation capacities but with lower complexation stability constants (KML ranged from 0.3 to 7.9 × 105) than C2 (KML ranged from 3.1 to 10.0 × 105). 2D-COS FTIR showed that the COO− and C-O in phenolic were the most important functional groups for interaction with studied metallic ions. [ABSTRACT FROM AUTHOR]

Structure formation in the chitosan + L-(D-)aspartic acid + water system during the spontaneous formation of polymer nanoparticles is discussed. The molar electric conductivity of chitosan L-(D-)asparaginate solutions in Kohlrausch coordinates decreases with increasing polymer concentration due to a decrease in the mobility of the ions of the acid residue under the action of the electrostatic potential of the macroion. The concentration dependence of the specific electric conductivity and the hydrodynamic parameters indicate partial compensation of the charges of macrochains through the formation of –anion ion pairs. The discovered tendencies are a complex function of association of counterions with the polycation, leading to phase segregation of the polymer substance at the nanoparticle level. The counterionic condensation effects and the diameter of the formed nanoparticles are largely determined by the [acid] : [~–NH2] molar ratio and the enantiomeric form of the acid residue. [ABSTRACT FROM AUTHOR]

This study deals with a search for relationships between the composition and properties of CaCO3 in bile and amino acid concentrations in it. Twenty two calcium carbonate samples were synthesized in bile by varying the concentrations of the amino acids histidine (His), methionine (Met), arginine (Arg), and tryptophan (Trp). It was found by thermodynamic modeling that the introduction of amino acids increases the stability of bile due to the reduction of the mole fraction of free Ca2+ ions. The CaCO3 content in the solid phase of the synthesized samples was determined; the maximum content was found for the samples obtained with Arg, and the minimum one, for those obtained with Met. The X-ray diffraction (XRD) analysis and Fourier transform IR spectroscopy studies showed that all the resulting powders were based on vaterite. For the amino acids Met and Arg, their stabilizing effect in relation to metastable aragonite was proved. Optical microscopy showed the presence of vaterite spherulites in all the resulting powders. It was established by photon correlation spectroscopy (PCS) that calcium carbonate microparticles with a radius of less than 10 μm are represented by three fractions. All the amino acids under study can be used as medicines for treatment and prevention of microcholelithiasis. [ABSTRACT FROM AUTHOR]

The complexation behavior in systems containing Ni2+, MoO42-, P2O74-, Cit3- - ions have been thoroughly investigated. The study determined the composition and instability constants of both mono- and biligand complex compounds at a constant ionic strength of the solution (Ic=1). By analyzing the concentration ratios of the complexing agent and ligands, the composition of mono- and polyligand complexes was elucidated. The complexation study utilized the potentiometric method, which is based on the functional dependence of the potential of the indicator electrode on the concentration of the complexing agent ions. The results enabled the calculation of the ionic composition of aqueous solutions of nickel complexes with citrate and diphosphate ions, depending on their concentrations. A proposed scheme for the formation of heteronuclear nickel-molybdenum complexes takes into account the sequence of component introduction into the electrolyte to form complexes of a specific composition. These findings were applied to develop electrolyte compositions for coating with alloys based on iron subgroup metals with molybdenum. These alloys exhibit several valuable properties, including corrosion resistance, electrocatalytic activity in hydrogen production, and enhanced operational characteristics. [ABSTRACT FROM AUTHOR]

[Display omitted] • Interfacial complexation of Fe3+ and Bi 2 MoO 6 is established in the presence of PDS. • The complexation between Fe3+ and Bi 2 MoO 6 accelerates the Fe3+/Fe2+ cycle. • Efficient organic contaminants degradation is achieved by Bi 2 MoO 6 /Fe3+/PDS/Vis system. • The Fe3+/Fe2+ redox cycle is employed to promote the continuous activation of PDS. To address the observed decrease in efficiency during Fe2+-mediated persulfate (PDS) activation caused by slow electron transfer rates and challenges in cycling between Fe3+/Fe2+ states, we devised a strategy to establish interfacial complexation between Fe3+ and Bi 2 MoO 6 in the presence of PDS. The proposed approach facilitates more efficient capture of photogenerated electrons, thereby accelerating the rate-limiting reduction process of the Fe3+/Fe2+ cycle under visible light irradiation and promoting PDS activation. The Bi 2 MoO 6 /Fe3+/PDS/Vis system demonstrates complete degradation of organic pollutants, including Atrazine (ATZ), carbamazepine (CBZ), bisphenol A (BPA), and 2,4-dichlorophenol (DCP) at a concentration of 10 mg/L within a rapid reaction time of 30 min. Radical scavenging experiments and electron paramagnetic resonance spectra (EPR) confirm that the sulfate radical (•SO 4 −) is the dominant species responsible for organic contaminant degradation. The real-time conversion process between Fe3+ and Fe2+ was monitored by observing changes in iron species forms and concentrations within the reaction system. X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy verify the formation of a complexation between Fe3+ and Bi 2 MoO 6 , facilitating anchoring of Fe3+ onto material surface. Based on these findings, we propose a reliable mechanism for the activation reaction. This work presents a promising heterogeneous PDS activation method based on Fe3+/Fe2+ cycle for water treatment. [ABSTRACT FROM AUTHOR]

Rare earth elements (REEs) have recently been classified as critical and strategic metals due to their importance in modern society. Research on the geochemical behaviors and mineralization of REEs not only provides essential guidance for mineral exploration but also holds great significance in enhancing our understanding of Earth's origin and evolution. This paper reviews recent research on the occurrence characteristics, deposit types, and hydrothermal behaviors of REEs, with a particular focus on comparing the complexation and transport of REEs by F, Cl, S, C, P, OH, and organic ligands in fluids. Due to the very weak hydrolysis of REE ions, they predominantly exist as either hydrated ions or free ions in low-temperature and acidic to weakly basic fluids. As the ligand activity increases, the general order of transporting REEs is Cl− ≈ S O 4 2 − > F− ≈ P O 4 3 − > C O 3 2 − > OH− under acidic conditions or OH− > S O 4 2 − ≈ Cl− > F− under alkaline conditions. In acidic to neutral hydrothermal systems, the transport of REEs is primarily dominated by S O 4 2 − and Cl− ions while the deposition of REEs could be influenced by F−, C O 3 2 − , and P O 4 3 − ions. In neutral to alkaline hydrothermal systems, REEs mainly exist in fluids as hydroxyl complexes or other ligand-bearing hydroxyl complexes. Additionally suggested are further comprehensive investigations that will fill significant gaps in our understanding of mechanisms governing the transport and enrichment of REEs in hydrothermal fluids. [ABSTRACT FROM AUTHOR]

Palladium-107 is one of the selected radionuclides in the safety assessment of geological disposal of radioactive waste. Although isosaccharinic acid (ISA) forms strong complexes with many elements and enhances element solubility, the thermodynamic evaluation of the complex of Pd with ISA has not been conducted. In this study, the solubility of Pd(OH)2 at pH 8.5–12.5 in the presence of ISA was investigated under inert gas (N2) atmosphere. Furthermore, the coordination state of aqueous Pd and ISA was investigated by X-ray absorption and Fourier transform infrared spectroscopy, respectively. According to experimental results, the number of OH ligands in the mixed complex depends on pH. The thermodynamic model and conditional equilibrium constants of the Pd-ISA complex were estimated by slope analyses of solubility experiments at different pH levels and ionic strengths based on the specific ion interaction theory. Hence, the impact of complexation with ISA on Pd(II) solubility under disposal conditions could be quantified using the proposed thermodynamic models in this study. [ABSTRACT FROM AUTHOR]

Some transformations involving AuCl(PPh3) in CH3CN/H2O solution are considered and compared with data known for auranofin. The reaction with GSH leads to the formation of binuclear complex (GSH)[Au(PPh3)]2 (at CGSH/CAu < 0.5) or mononuclear complex Au(GSH)(PPh3) (CGSH/CAu > 0.5); PPh3 substitution is not observed. The reaction with BSA leads to Cl– substitution. A cyclic voltammetry study showed the presence of several peaks of irreversible oxidation of AuCl(PPh3) and complexes with GSH. [ABSTRACT FROM AUTHOR]

This research demonstrated and analyzed the complexation capabilities of the dipodal chelator N¹,N³-bis(2-((E)-2,3,4-trihydroxybenzylidene)amino)ethyl)malonamide (MEP) with heavy metal ions, viz., Al3+, Fe3+, and Cr3+, by engaging potentiometric and spectrophotometric methods. The whole experiment was carried out in a pH-dependent manner in a highly aqueous medium with a pH range of 2 to 11. The potentiometric and spectrophotometric results suggest the highest binding affinity of the chelator MEP with Al3+ metal ions among all three metal ions under study, with a stability constant value of log β = 27.13. [ABSTRACT FROM AUTHOR]

Complexometric titration is often used for determining the metal content, either through direct titration or back titration. This study aimed to investigate redox titration between Mohr salt solutions and potassium dichromate in an acidic atmosphere in the pH range 2. The results showed that the reaction proceeded effectively at pH 2, with Mohr's salt solution acting as titrant. Furthermore, experiments were conducted to compare the effectiveness of EDTA ligands and SCN- ligands in improving the sharpness of the Fe2+/ Cr2O72- redox titration curve at pH 2. Results show that EDTA ligands are more effective than SCN- ligands in improving the sharpness of the titration curve. However, it should be noted that the addition of EDTA ligands can shift the equivalent point volume earlier, so adjustments need to be made in redox titration analysis. Research has also shown that adding excess moles of EDTA to total Fe (II) ions can decrease redox potential in Fe2+/ Cr2O72- systems. These results provide additional insight into the use of EDTA ligands in redox titration analysis and their relevance to redox potential changes in the systems studied.

Research efforts on permanganate (Mn(VII)) combined with redox-mediator (RM), have received increasing attention due to their significant performance for bisphenol-A (BPA) removal. However, the mechanisms underpinning BPA degradation remain underexplored. Here we show the overlooked interactions between RM and BPA during permanganate oxidation by introducing an RM—N-hydroxyphthalimide (NHPI). We discovered that the concurrent generation of MnO2 and phthalimide-N-oxyl (PINO) radical significantly enhances BPA oxidation within the pH range of 5.0–6.0. The detection of radical cross-coupling products between PINO radicals and BPA or its derivatives corroborates the pivotal role of radical cross-coupling in BPA oxidation. Intriguingly, we observed the formation of an NHPI-BPA complex, which undergoes preferential oxidation by Mn(VII), marked by the emergence of an electron-rich domain in NHPI. These findings unveil the underlying mechanisms in the Mn(VII)/RM system and bridge the knowledge gap concerning BPA transformation via complexation. This research paves the way for further exploration into optimizing complexation sites and RM dosage, significantly enhancing the system's efficiency in water treatment applications.

A comprehensive thermodynamic and structural study of the complexation affinities of tetra (L1), penta (L2), and hexaphenylalanine (L3) linear peptides towards several inorganic anions in acetonitrile (MeCN) and N,N-dimethylformamide (DMF) was carried out. The influence of the chain length on the complexation thermodynamics and structural changes upon anion binding are particularly addressed here. The complexation processes were characterized by means of spectrofluorimetric, 1H NMR, microcalorimetric, and circular dichroism spectroscopy titrations. The results indicate that all three peptides formed complexes of 1:1 stoichiometry with chloride, bromide, hydrogen sulfate, dihydrogen phosphate (DHP), and nitrate anions in acetonitrile and DMF. In the case of hydrogen sulfate and DHP, anion complexes of higher stoichiometries were observed as well, namely those with 1:2 and 2:1 (peptide:anion) complexes. Anion-induced peptide backbone structural changes were studied by molecular dynamic simulations. The anions interacted with backbone amide protons and one of the N-terminal amine protons through hydrogen bonding. Due to the anion binding, the main chain of the studied peptides changed its conformation from elongated to quasi-cyclic in all 1:1 complexes. The accomplishment of such a conformation is especially important for cyclopeptide synthesis in the head-to-tail macrocyclization step, since it is most suitable for ring closure. In addition, the studied peptides can act as versatile ionophores, facilitating transmembrane anion transport. [ABSTRACT FROM AUTHOR]

This study assessed the effect of whey protein isolate (WPI) and its coconut oil complexes (CO-WPI) on the viability of Limosilactobacillus reuteri KUB-AC5 during spray drying and storage. Varied CO concentrations (0%, 4%, and 8%, w/w) and spray drying temperatures (110 °C and 130 °C) influenced secondary structures, free sulfhydryl groups, disulfide bonds, and DPPH• and ABTS•+ scavenging activities of WPI. Throughout the spray drying and storage processes, CO-WPI effectively reduced lipid peroxidation in the probiotic membranes, as detected by advanced 1H-nuclear magnetic resonance, compared to WPI alone. Microencapsulation in 4CO-WPI at 110 °C provided the highest cell viability during drying (1.34 × 1011 CFU g−1), coupled with the highest cholesterol assimilation (58.43%). After 12 months at 4 °C, viability remained high (5.57 × 1010 CFU g−1). This study demonstrated CO-WPI's potential in reducing oxidative damage and improving probiotic survival, highlighting its efficacy as a microencapsulant in spray drying. [ABSTRACT FROM AUTHOR]

Flumequine ligand (FLQ) metal complexes of the [M(FLQ)2(Cl)(H2O)].nH2O type, where M are (La(III), Sm(III), and Tb(III)) and FLQ is flumequine have been synthesized. The FLQ metal complexes could be prepared using MCl3 : flumequine in stoichiometry of 1:2 in situ bidentate chelation. The characterization of FLQ complexes obtained have been done using elemental analyses (%C, %H and %N), molar conductivity (Λm), infrared spectroscopy (FTIR), electronic spectra (UV-Vis), thermal analysis (TGA), and physicochemical techniques such as X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) measurements at room temperature. Accordingly, these complexes are indicative of an octahedral coordination structure. Flumequine ligand has a bidentate fashion through the oxygen atoms of carbonyl (quinolone) and carboxylic groups. The findings demonstrated the anti-cancer efficacy of these compounds against HepG-2 and MCF-7 cancer cell lines at extremely low doses of up to 58.2 · g/mL. The La(III) complex was shown to have the highest selectivity against cancer cells in comparable with both samarium and terbium(III) complexes. [ABSTRACT FROM AUTHOR]

[Display omitted] Zn-Ni batteries have garnered considerable attention due to their high specific energy, consistent discharge voltage, favorable performance at low temperatures, and environmentally benign nature. Nevertheless, anode interface issues such as dendrite growth, hydrogen evolution, and interfacial side reactions lead to poor cycling stability of Zn-Ni batteries, significantly limiting their further commercial applications. In this study, we propose a facile electrolyte engineering strategy to optimize the Zn anode interfacial environment and stabilize the Zn anode by introducing tannic acid (TA) into the KOH electrolyte. The incorporated TA complexing agent addition will be used to prevent the direct contact of H 2 O with the anode surface and promote the desolvation of Zn2+ through complexation, thus suppressing the interfacial corrosion. Consequently, the Zn symmetric battery using TA electrolyte cycles stably for 178 h at 1 mA cm−2. The Zn-Ni full batteries with TA electrolyte maintain 98.08 % capacity retention after 2000 cycles at 20C. This study will be of immediate benefit in commercializing large-scale, practical energy storage applications. [ABSTRACT FROM AUTHOR]

5-Hydroxy-6-methyluracil (5-OH-6-MU) was shown to form a 1:1 complex with N-acetylcysteine (N-AC), i.e., the compounds interacted in an equimolar ratio. The temperature dependence of the stability constant was studied in the range 291-316 K. The thermodynamic parameters of the complexation process were determined. Aprocedure for the synthesis of the 5-OH-6-MU...N-AC complex was developed based on the results. The toxicity and antihypoxic activity of the complex were subsequently studied. The synthesized compound at a dose of 500 mg/kg in mice had low toxicity and antihypoxic activity significantly superior to those of the reference drugs (5-OH-6-MU and N-AC). [ABSTRACT FROM AUTHOR]

The structure characteristics of lignin were summarized・ The inhibitory mechanism of lignin on Gram-positive and Gram-negative bacteria was described, that is, the phenol hydroxyl group can promote the decrease of pH value around cells, thus destroying cell membranes, denaturating proteins, inhibiting the activity of respiratory system and electron transfer enzyme system of microbial cells, and achieving the inhibitory effect, while the reduction of molecular weight can increase the phenol hydroxyl group content of lignin・ The water solubility of lignin can be improved effectively with the increase of hydrophilicity ・ Based on the research status at home and abroad, the main methods to improve the antibacterial activity of lignin (depolymerization, fractionation, extraction of lignin and lignin-silver complex) were introduced, the methods for improving the antibacterial activity of lignin modified by different methods were discussed, and the prospect of improving the antibacterial activity of lignin was also discussed. [ABSTRACT FROM AUTHOR]

The interaction of indotricarbocyanine dyes with lipid-transfer protein Ns-LTP1 in Dulbecco's phosphate-buffered saline (PBS) was studied. An orthophenylene bridge with a chlorine in the meso-position of the dye was shown to be ineffective as a linker for protein macromolecules without a free cysteine residue. The indotricarbocyanine dye was modified into the N-hydroxysuccinimide ester to obtain a complex of the indotricarbocyanine dye with the Ns-LTP1 protein. A complex of dye molecules with the Ns-LTP1 protein was obtained by mixing a two-phase system of the protein in PBS and the dye activated ester in 1,2-dichloroethane. The half-width of the absorption spectrum increased from 56 to 61 nm; the fluorescence decay time, from 0.3 to 0.5 ns; and the degree of polarization, from 27 to 31% upon formation of the complex. It was established that HCl at concentrations equivalent to its content in gastric juice (0.1–0.5%) led to irreversible destruction of the dye. Capsules that can withstand stomach acid and dissolve in the intestines could be used to treat erosive and ulcerative lesions with peroral administration of the complex. [ABSTRACT FROM AUTHOR]

The stereospecific analysis of chiral molecules is an important issue in many scientific fields. In separation sciences, this is achieved via the formation of transient diastereomeric complexes between a chiral selector and the selectand enantiomers driven by molecular interactions including electrostatic, ion‐dipole, dipole‐dipole, van der Waals or π‐π interactions as well as hydrogen or halogen bonds depending on the nature of selector and selectand. Nuclear magnetic resonance spectroscopy and molecular modeling methods are currently the most frequently applied techniques to understand the selector‐selectand interactions at a molecular level and to draw conclusions on the chiral separation mechanism. The present short review summarizes some of the recent achievements for the understanding of the chiral recognition of the most important chiral selectors combining separation techniques with molecular modeling and/or spectroscopic techniques dating between 2020 and early 2024. The selectors include polysaccharide derivatives, cyclodextrins, macrocyclic glycopeptides, proteins, donor‐acceptor type selectors, ion‐exchangers, crown ethers, and molecular micelles. The application of chiral ionic liquids and chiral deep eutectic solvents, as well as further selectors, are also briefly addressed. A compilation of all published literature on chiral selectors has not been attempted. [ABSTRACT FROM AUTHOR]

Belonging to the class II drugs according to the biopharmaceutics classification system, silibinin (SLB) benefits from high permeability but suffers poor solubility that negatively affects the development of any delivery system. This research aimed to improve SLB solubility by combined use of co-solvency and complexation phenomena. Solubility studies were performed using the phase solubility analysis according to the shake-flask method in the presence of ethanol and 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) as a co-solvent and inclusion complexing agent, respectively. SLB release studies from chitosan nanoparticles were carried out in double-wall, diffusion cells using the optimized drug release medium. SLB solubility was mathematically optimized constraining to using the lowest concentrations of ethanol and HP-β-CD. SLB solubility increased linearly with the increase of HP-β-CD concentration. The solubility in PBS-ethanol mixtures followed a log-linear model. SLB solubility in the presence of the ethanol co-solvent and HP-β-CD complexing agent was optimized by adopting a genetic algorithm suggesting the phosphate buffer saline solution supplemented by 6%v/v ethanol and 8 mM HP-β-CD as an optimized medium. The optimized solution was examined to study SLB release from chitosan nanoparticles (4.5 ± 0.2% drug loading) at 37 °C under static conditions. The sigmoidal release profile of SLB from the particles indicated a combination of erosion and diffusion mechanisms governing drug release from the nanoparticles. SLB solubility in a buffered solution supplemented by ethanol co-solvent and HP-β-CD complexing agent is a function of free drug present in the semi-aqueous media, the drug-ligand binary complex, and the drug/ligand/co-solvent ternary complex. [ABSTRACT FROM AUTHOR]

The rising use of antibiotics and antioxidants in medicine and animal care has primarily contributed to antibiotic-resistant microbes, decreased oxidative stress, and prompted the hunt for novel and effective medications. This study reports the synthesis, bioactivity, and radical scavenging potential of N-(pyridin-4-yl)(tolu-4-yl)sulphonamide coordinated with zinc (II), copper (II), cobalt (II), and cadmium (II) ions. The condensation reaction of 4-aminopyridine and tosyl chloride produced the sulphonamide derivative. The complexes were synthesized by the reaction of ZnCl2 /Cu(NO3)2.6H2O, Co(NO3)2.6H2O, Cd(NO3)2.6H2O with the sulphonamide derivative. The antimicrobial analysis was conducted via the conventional method, and the free radical scavenging activity was achieved through the use of a 2,2-diphenyl-1-picrylhydrazyl (DPPH) solution. These compounds were characterized by physicochemical analysis, UV-VIS, FT-IR, NMR (1H and 13C) and LC-MS. The ligand and its new complexes were tested against gram (-) Escherichia coli, gram (-) Salmonella typhi, gram (+) Staphylococcus aureus, Aspergillus flavus, Aspergillus niger, and Saccharomyces cerevisiae. The findings revealed that some of the complexes have significant activity against some pathogens and show good free radical scavenging activity. The heterocyclic pyridine nitrogen in the sulphonamide is a good site for complaxation, and the methods employed and the synthesized compounds are viable sources of knowledge for the chemical and pharmaceutical industries. The study recommends further investigation into the formation of new complexes and their bioactivity with other clinical pathogens. [ABSTRACT FROM AUTHOR]

The understanding of the thermodynamic stability and speciation of metal complexes in solution requires access to their enthalpy and entropy of formation. In this work, we specifically focus our investigation on the complexation process of silver(I) ion in acetonitrile (AN) with substituted mono pyridines and cyclic monoamines. The aim of this study is to provide reliable thermodynamic data to obtain insights on metal complex formation, focusing on ligands donor properties and solvation effects. Carefully designed potentiometric and calorimetric experiments allowed to define the species present at different ligand/metal ratios and to obtain the complex formation constants and enthalpies. In general, the enthalpy terms associated with the complex formation are highly exothermic, while the entropy values are always unfavorable. The formation constants of AgLj species for the ligands investigated in AN are compared with those previously obtained in dimethyl sulfoxide (DMSO) and water. The trends in stability constants and enthalpy values are discussed in relation to the pKa data available in the different solvents. Higher pKa values correspond to greater ligand basicity and result in more stable and more enthalpy stabilized complexes. [ABSTRACT FROM AUTHOR]

This study was conducted to investigate the ability of hesperidin (HES) to form metal-complexes (HES-M) by chelation with transition metals such iron(III), copper(II), zinc(II), and silver(I), in addition to screen the antioxidant activity (DPPH free radical scavenging and phosphomolybdenum reduction potential methods PRP), anti-Alzheimer activity [(acetylcholinesterase (AChE)] inhibition assay) and coagulant activity (prothrombin time PT assay). The results indicated that HES could form a 1:1 complex with the studied metals in methanolic solution. The complex has been synthesized and characterized by physicochemical methods. Complexing of hesperidin with metals leads to increase in the antioxidant activity by 15.4-33%. Also, the total antioxidant capacities of HES-M complexes were increased by 13.8-251%. Cu-complex revealed the most increasing antioxidant activity by 33% for DPPH scavenging activity and 251% for PRP activity. The inhibition capacity of the HES, as well as of the HESM complexes on the enzyme AChE, was revealed that only HES-Zn complex has higher anti-Alzheimer activity (IC50 1.18 mg/mL). HES and HES-M complexes led to accelerate the clotting time by 28.9-67.3%, where HES-Zn complex was the most accelerating clotting time by 67.3%. The high increase in total antioxidant activity of hesperidin after chelating with copper (251%) opens the door for further research. [ABSTRACT FROM AUTHOR]

A colorimetric sensing method for salicylic acid (SA) was developed by designing and fabricating bimetallic oxide nanozymes. Firstly, by calcinating MIL-100(Fe)@PMo12 (MOFs@POMs) at different temperature, Fe2(MoO4)3-Ts (T = 400℃, 500℃, 600℃, 700℃) nanoparticles (NPs) were successfully prepared. Secondly, by evaluating the peroxidase-like activities, Fe2(MoO4)3–600 NPs shows the best peroxidase-like activity attributed to the Fenton-like effect and the synergistic coupling interaction between Mo and Fe. Finally, based on the specific complexation between SA and Fe3+, a sensitive colorimetric sensor for SA was established, which exhibits superior selectivity and interference with a detection limit of 0.11 μM and a linear range of 10 to 100 μM, the lowest LOD for SA to date, to the best of our knowledge. [ABSTRACT FROM AUTHOR]

Zinc 13-(N,N-diethylamino)methyl-3,3,7,8,12,17,18-heptaethyl-2-oxochlorin was prepared from 2,3,7,8,12,13,17,18-octaethylporphyrin via the regioselectively acid-catalyzed double dehydration of cis-12,13-diethyl-ds-12,13-dihydroxy-2-oxobacteriochlorin to the corresponding 12-ethyl-13-vinyl-2-oxochlorin. The synthetic zinc amino-oxochlorin was axially ligated with the imidazolyl group of Nα-protected histidines in chloroform, and concomitantly the amino group of the former was hydrogen-bonded with the carboxy group of the latter. The resulting two-point bonding supramolecules served as models for the complexes of chlorophylls with peptides in photosynthetic apparatuses including light-harvesting antennas and charge-separating reaction centers. A similar 1:1 complex was produced by the interaction of the zinc amino-chlorin with the related methionine possessing thioether and carboxylic acid moieties. [ABSTRACT FROM AUTHOR]

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Spectrophotometry is used to determine constants of stability for coordination compounds of apple pectin with indole and L-tyrosine—structural analogs of aromatic amino acids (tryptophan and phenylalanine). It is found that the presence of phenolate oxygen in tyrosine favors bonding to pectin and is attributed to this species' participation in the forming of H bonds with the carbonyl functional group of the polysaccharide, which ensures better stability of the pectin–tyrosine complex than that of a pectin–phenylalanine system. It is shown that the key contribution to the stability of pectin complex comes from the indole moiety of tryptophan. Based on analysis of thermodynamic characteristics, it is shown that the formation of 1 : 1 molecular complexes for pectin–indole and pectin–tyrosine systems is governed only by the enthalpy component (∆H0 < 0, ∆S0 < 0). The thermal properties of modified pectins are determined. [ABSTRACT FROM AUTHOR]

The paper presents the thermodynamic parameters of acid–base equilibria of 1-methyl-2-mercaptoimidazole (1MI) and its complexation with the silver(I) ion in aqueous dimethylsulfoxide. An analysis of the solvation contributions of reagents to the change in the Gibbs energy of protonation of 1MI showed that the practically zero changes in the Gibbs energy of the transfer of the reaction from water to a solvent with a composition of 0.1 mole fractions DMSO are due to complete compensation of the solvation contribution of the protonated 1-methyl-2-mercaptoimidazole and proton, and also to the insignificant change in the solvation state of 1MI. At higher DMSO concentrations in the solvent, an increase in the negative values of the Gibbs energy of the 1MI protonation transfer is accompanied by a predominant contribution from increased solvation of the protonated form of 1MI along with the negative contribution from resolvation of proton and 1MI. Both in water and in water–dimethylsulfoxide solvents, the silver(I) ion forms three complex species with 1MI, whose stability increases at increased DMSO contents. Stabilization of 1MI and silver ion transferred from water to the H2O–DMSO solvents makes a negative contribution to the change in the Gibbs energy of the transfer of the monocomplex formation reaction. [ABSTRACT FROM AUTHOR]