Sulfide Anion Research Articles

A simple Cu(II)-dppy complex for selective detection of hazardous sulfide anion in water and its application in DNA and BSA binding

The traditional hazardous sulfide species (S2–, HS–, and H2S) are widely dispersed throughout the environment and have widespread applications in various industrial processes. Despite numerous applications, excessive exposure to sulfide species can lead to several chronic diseases. In light of the importance of sulfide detection in water, we have reported a novel water-soluble 1:2 copper complex ([CuL2]Cl2) of 2,2′-(4-(3,4-dimethoxyphenyl)pyridine-2,6-diyl)dipyrazine ligand L. The [CuL2]Cl2 receptor has been utilized for the sulfide detection in the vicinity of other anions of higher concentration (ten equivalents of F−, I −, Br−, Cl−, H2PO4−, NO3− HCO3−, OH−, CH3CO2−, SO42−, CO32−, PPi, SO32−, HPO42−, S2O32− (10 mM)) in water at physiological pH 7.4 (10 mM HEPES buffer) with the help of absorption spectral studies and colorimetric study. The detection limit of sulfide is calculated to be 1.13 µM. DFT calculations suggested that the most exergonic free energy (-31.99 kcal/mol) is associated with sulfide, leading to the displacement of Cu(II) ion from the [CuL2]Cl2 receptor, which well supported the experimental absorption spectral data. In addition, [CuL2]Cl2 receptor also demonstrated noteworthy interactions with Calf-Thymus DNA (CT-DNA) and bovine serum albumin (BSA).

Sulphide and iodide anion recognition by a selective copper hydrogel of a chloro substituted terpyridine ligand

2,2′:6′,2″-Terpyridines (tpy) are well known for their ability to form a gel in the presence of transition metals. Due to the strong binding affinities towards transition metal ions aided by non-covalent interactions, tpy tends to form hydrogel with more than one metal ion. Interestingly, a simple chloro substituted 2,2′:6′,2″-terpyridine ligand L selectively forms a gel with only Cu(II) ion in a mild acidic medium. The hydrogel has a fibrous structure and is sensitive to S2− and I− anions, which is confirmed by both morphological analysis and rheological study. The copper complex was characterized using a variety of techniques, including HRMS, ESR, FTIR, elemental analysis, and DFT calculations. Further, DFT calculations were used to study the non-covalent interactions within the complex and to understand why the hydrogel responds to specific anions. The free energies of the CuI and CuS precipitate formation were calculated to get an idea of the feasibility of the process. Notably, UV–visible absorption spectroscopic study shows that the copper(II) complex CuCl2L selectively detected S2− and I− anions in aqueous acetonitrile with LOD of 2.63 and 2.08 μM, respectively.

Denitrative Formal [5+1] Cycloaddition of 1‐(2‐Nitrophenyl)‐2‐Yn‐1‐Ones with Thioacetamide under Transition‐Metal‐Free Conditions: Synthesis of Thiochromen‐4‐Ones

AbstractA new strategy for thiochromen‐4‐one synthesis that relies on the denitrative formal [5+1] cycloaddition of 1‐(2‐nitrophenyl)‐2‐yn‐1‐ones with thioacetamide is described. Achieved under reaction conditions that did not require transition metal catalysis, nor the exclusion of air or moisture, the reaction is suggested to involve exploiting the propensity of thioacetamide to undergo hydrolysis under basic conditions. This is follows by addition of the ensuing sulfide anion to the 1,3‐alkynone and a nucleophilic aromatic substitution and denitrative rearomatization cascade to give the S‐heterocyclic product in yields of 41–99 %.

СООТНОШЕНИЕ H2S/ГОМОЦИСТЕИН КАК ПОТЕНЦИАЛЬНЫЙ БИОМАРКЕР ПРОГНОЗИРОВАНИЯ ПРОГРЕССИРОВАНИЯ АРТЕРИАЛЬНОЙ ГИПЕРТЕНЗИИ У ДЕТЕЙ

Background. The H2S/homocysteine ratio is a potential biomarker for predicting the progression of cardiovascular diseases. The purpose. To establish the features of changes in the H2S/homocysteine ratio in children with arterial hypertension. Material and methods. A total of 111 children aged 14 to 18 years were examined. Based on the results of 24-hour blood pressure monitoring (n=81), two groups were formed: group 1 (n=51) – children with arterial hypertension (AH), group 2 (n=30) – children with high-normal blood pressure (HNBP). Group 3 included 30 healthy children. Plasma homocysteine level was determined by high-pressure liquid chromatography [Naumov A.V. et al., 2010]. The level of endogenous hydrogen sulfide was assessed by spectrophotometric method based on the reaction between sulfide anion and an acidic solution of the reagent N, N-dimethyl-p-phenylenediamine hydrochloride [Norris Eric J., 2011]. Results. A significant increase in plasma homocysteine concentration was revealed in patients with AH and HNBP compared with healthy children. The plasma levels of hydrogen sulfide in children with AH were significantly lower than in the comparison group. Hypertensive children in comparison to healthy children showed significantly lower plasma H2S/homocysteine ratio. Correlations have been established between the H2S/homocysteine ratio and plasma levels of homocysteine and hydrogen sulfide. Conclusions. Hypertensive children have a lower H2S/homocysteine ratio, which is due to the presence of hyperhomocysteinemia and reduced H2S levels. The H2S/homocysteine ratio can be used as a potential marker for predicting the progression of AH.

Formation of 2D Amorphous Lithium Sulfide Enabled by Mo2C Clusters Loaded Carbon Scaffold for High-Performance Lithium Sulfur Batteries.

Lithium-sulfur (Li-S) batteries, operated through the interconversion between sulfur and solid-state lithium sulfide, are regarded as next-generation energy storage systems. However, the sluggish kinetics of lithium sulfide deposition/dissolution, caused by its insoluble and insulated nature, hampers the practical use of Li-S batteries. Herein, leaf-like carbon scaffold (LCS) with the modification of Mo2C clusters (Mo2C@LCS) is reported as host material of sulfur powder. During cycles, the dissociative Mo ions at the Mo2C@LCS/electrolyte interface are detected to exhibit competitive binding energy with Li ions for lithium sulfide anions, which disrupts the deposition behavior of crystalline lithium sulfide and trends a shift in the configuration of lithium sulfide toward an amorphous structure. Combining the related electrochemical study and first-principle calculation, it is revealed that the formation of amorphous lithium sulfides shows significantly improved kinetics for lithium sulfide deposition and decomposition. As a result, the obtained Mo2C@LCS/S cathode shows an ultralow capacity decay rate of 0.015% per cycle at a high mass loading of 9.5mg cm-2 after 700 cycles. More strikingly, an ultrahigh sulfur loading of 61.2mg cm-2 can also be achieved. This work defines an efficacious strategy to advance the commercialization of Mo2C@LCS host for Li-S batteries.

Ratiometric Sensing of Azithromycin and Sulfide Using Dual Emissive Carbon Dots: A Turn On-Off-On Approach.

A novel ratiometric fluorescence probe was developed for the determination of azithromycin (AZM) and sulfide ions based on the differential modulation of red emissive carbon dots (R-N@CDs) and blue emissive carbon dots (B-NS@CDs). The addition of sulfide anion selectively quenched the red emission of R-N@CDs while the blue emission of B-NS@CDs unaffected. Upon subsequent introduction of AZM to this R-N@CDs@sulfide system, the quenched red fluorescence was restored. Comprehensive characterization of the CDs was performed using UV-Vis, fluorescence, FTIR spectroscopy, XPS, and TEM. The proposed method exhibited excellent sensitivity and selectivity, with limits of detection of 0.33 µM for AZM and 0.21 µM for sulfide. Notably, this approach enabled direct detection of sulfide without requiring prior modulation of the CDs with metal ions, as is common in other reported methods. The ratiometric probe was successfully applied for the determination of AZM in biological fluids and sulfide in environmental water samples with high selectivity. This work presents the first fluorometric method for the detection of AZM in biological fluids.

Selective sensing of sulphide ion by a simple mercury (II) complex of an amino-substituted terpyridine in aqueous solution

A novel mercury complex HgCl2L of 4′-(4-N,N´-dimethylaminophenyl)-2,2´:6′,2´´-terpyridine ligand L has been synthesized and characterised using 1H NMR, HRMS, FT-IR spectroscopy and CHN analysis. The crystal structure of HgCl2L exhibits distorted square pyramidal geometry. Further, the complex HgCl2L is utilised for selectively detecting sulphide (S2−) anion with other competitive anions in aqueous acetonitrile (4:1 v/v) medium. UV–visible absorption spectral studies and colorimetric approach confirmed the selectivity of the complex towards S2- and the limit of detection has been determined to be 1.01 μM.

RbEr2AsS7: A Rubidium-Containing Erbium Sulfide Thioarsenate(III) with (S2)2− Ligands According to RbEr2S(S2)[AsS2(S2)

The new rubidium-containing erbium sulfide thioarsenate(III) with the structured formula RbEr2S(S2)[AsS2(S2)] was obtained from the syntheses of elemental erbium (Er), arsenic sesquisulfide (As2S3) and rubidium sesquisulfide (Rb2S3) with elemental sulfur (S) at 773 K as transparent, orange, needle-shaped crystals. RbEr2AsS7 crystallizes monoclinically in the space group C2/c with a = 2339.86(12) pm, b = 541.78(3) pm, c = 1686.71(9) pm and β = 93.109(3) ° for Z = 8. The crystal structure features complex [AsS2(S2)]3− anions with two S2− anions and a (S2)2− disulfide dumbbell coordinating end-on as ligands for each As3+ cation. Even outside the ligand sphere of As3+, S2− and (S2)2− can be found as sulfide anions. Two distinct Er3+ cations are surrounded by either nine or seven sulfur atoms. The [ErS9] polyhedra are corner- and face-connected, while the [ErS7] units share common edges, both building chains along [010]. These different chains undergo edge connectivity with each other, resulting in the formation of corrugated layers, which are held together by Rb+ in chains of condensed [RbS9] polyhedra. So, a three-dimensional network is generated, offering empty channels along [010] apt to take up the As3+ lone-pair cations. Wavelength-dispersive X-ray spectroscopy verified a molar Rb:Er:As:S ratio of approximately 1:2:1:7 and diffuse reflectance spectroscopy showed the typical f–f transitions of Er3+, while the optical band gap was found to be 2.42 eV.

Controlled and Regioselective Ring-Opening Polymerization for Poly(disulfide)s by Anion-Binding Catalysis.

Poly(disulfide)s are an emerging class of sulfur-containing polymers with applications in medicine, energy, and functional materials. However, the constituent dynamic covalent S-S bond is highly reactive in the presence of the sulfide (RS-) anion, imposing a persistent challenge to control the polymerization. Here, we report an anion-binding approach to arrest the high reactivity of the RS- chain end to control the synthesis of linear poly(disulfide)s, realizing a rapid, living ring-opening polymerization of 1,2-dithiolanes with narrow dispersity and high regioselectivity (Mw/Mn ∼ 1.1, Ps ∼ 0.85). Mechanistic studies support the formation of a thiourea-base-sulfide ternary complex as the catalytically active species during the chain propagation. Theoretical analyses reveal a synergistic catalytic model where the catalyst preorganizes the protonated base and anionic chain end to establish spatial confinement over the bound monomer, effecting the observed regioselectivity. The catalytic system is amenable to monomers with various functional groups, and semicrystalline polymers are also obtained from lipoic acid derivatives by enhancing the regioselectivity.

The aluminum chemistry involved redox mechanisms in transition metal dichalcogenides

Transition metal dichalcogenides (TMDs) featured an open framework structure and versatile electronic properties are attractive for their higher capacitance when used as cathodes for aluminum-ion batteries (AIBs). However, the inexhaustive understanding of cell chemistry involving complicated charge transfer stalls the deployment of this type AIBs electrode materials. Here the sulfide materials of MS2 (M = Fe, Ni, Co) served as emblematic conversion-type electrodes are taken as models to shed light on the regularity among the Al storage mechanisms in TMDs cathodes. To explain such chemistry, we therefore interrogate the redox mechanisms between MS2 (M = Fe, Ni, Co) from a broad range of experimental and mechanistic characterization perspectives. Remarkably, as indicated by characterization results, the detailed Al insertion and removal processes occurring in MS2 (M = Fe, Ni, Co) cathodes are revealed, accompanied by the anionic-redox reaction of sulfide anion (S2−), whereas the valence state transitions of the metal element in CoS2 (Co2+∼Co3+) also occur simultaneously during the insertion/extraction of Al3+. Using theoretical calculations, we further clarify the essential reasons for the mechanistic discrepancy, and discuss the energy storage regularity in TMDs. These foundations not only contribute to a profound understanding for the charge storage mechanisms in TMDs but also expand the palette of property boosting electrode materials for practical AIBs.

Dual-mode fluorescence and colorimetric sensing of sulfide anion in natural water based on near-infrared Ag2S quantum dots and MnO2 nanosheets complex

Near infrared (NIR) emission Ag2S quantum dots (QDs) are of great value for biochemical sensing with strong anti-interference and low toxicity. Herein, NIR fluorescence Ag2S QDs were synthesized successfully. Combined with the excellent oxidase-like characteristics of manganese dioxide (MnO2) nanosheets, a fluorescence and colorimetric dual-mode sensor for sulfide anion was developed. MnO2 nanosheets could effectively catalyze the oxidation of TMB to produce blue TMB oxide (ox TMB), at the same time, the fluorescence of Ag2S QDs could be effectively quenched by fluorescence internal filtration effect (IFE) and dynamic quenching effect. The enzyme-like activity was weakened and the NIR fluorescence of Ag2S QDs was restored when sulfide anion (S2−) was added, due to the reduction of MnO2 to Mn2+.The linear ranges for fluorescence and colorimetric analysis of S2− were 2–250 μM and 0.3–50 μM, with detection limits of 0.6 and 0.215 μM, correspondingly. The dual-mode sensor had a wider detection range, higher sensitivity and shorter reaction time, which could be used for highly selective detection of S2− in different concentration ranges. In addition, it had been successfully applied to the determination of sulfide in water samples with satisfactory accuracy and sensitivity.

Role of sulfide anion in the development of chronic alcoholic hepatitis under the conditions of modulation of adenosine monophosphate kinase – a correlational study

Introduction and aim. Hydrogen sulfide (H 2 S) has attracted the attention of researchers as a novel signaling molecule that affects vascular metabolism, immune function, stress and inflammation. It plays an important role in pathophysiological disorders under the conditions of the development of obesity, diabetes, non-alcoholic fatty liver disease and cardiovascular diseases. The purpose of this work is to establish correlation ratios of H 2 S concentration with markers of oxidative-nitrosative stress and extracellular matrix metabolism of the liver during chronic alcoholic hepatitis modeling and AMPK modulation by phenformin and doxorubicin. Material and methods. The experiments were performed on 36 white, sexually mature male Wistar rats, weighing 180-220 g. Alcoholic hepatitis was modelled by alcohol administration, on the background of alcoholic hepatitis animals received phenformin orally at a dose of 10 mg/kg or doxorubicin at a dose of 1.25 mg/kg intraperitoneally. Statistical processing of the results of biochemical studies was carried out using the non-parametric method of Spearman to determine correlations. Results. H 2 S during alcoholic hepatitis inversely proportionally strongly correlates with the concentration of nitrites, oxyproline and arginase activity. Phenformin administration during alcoholic hepatitis leads to formation of inversely proportionally strongly correlation of H 2 S with the production of superoxide anion radical, the concentration of malondialdehyde, activities of constitutive NO-synthases, nitrite reductases, nitrate reductases, and arginase. Doxorubicin administration during alcoholic hepatitis leads to formation of directly proportional strongly correlation of H 2 S with the activity of constitutive NO-synthases, nitrite reductases, nitrate reductases. Conclusion. Administration of phenformin or doxorubicin expands correlations between H 2 S and indicators of oxidative-nitrosative stress.

Structural and computational studies of Schiff base ligand and its metal complexes: Synthesis, solvent effects by post-synthetic modification, computational and selective hazardous sulfide anion detection

We have reported the synthesis and crystal structure analysis of the new Schiff base ligand (Z)-2,4-diiodo-6-(((2-(methylthio)phenyl)imino)methyl)phenol (SL6) and its copper complexes (complex-1: [Cu(SL6)(CH3COO)]n complex-2: [Cu(SL6)(CH3COO)(CH3COOH)]). Post-synthetic modification of complex-1 by solvent-induced effects leads to the formation of complex-2. The crystal structure and computational studies were used to investigate the influence of solvents on structural conformation, coordination polyhedral and supramolecular architecture. The copper complex-1 is a coordination polymer that exhibits interesting type-II halogen‧‧‧halogen tetramer synthon. In complex-2, the polymeric chain is replaced by the 1-D hydrogen-bonded chain influenced by the coordinated acetic acid. Hirshfeld surface, 2-D fingerprint plots, enrichment ratio and QTAIM analysis, were utilized to examine the nature of various noncovalent interactions. The DFT studies were conducted to investigate the electronic properties and local and global parameters of ligand and complexes. Furthermore, in-situ prepared Cu(SL6)(CH3COO)2 receptor was employed for selective detection of hazardous sulfide anion in the vicinity of other anions in aqueous acetonitrile HEPES buffer by utilizing UV–Visible spectroscopic and colourimetric study.

Detection of reed using cnn method and analysis of the dry reed (phragmites australis) for a sustainable lake area

BackgroundCommon reed (Phragmites australis L.) is a highly productive wetland plant and a possible valuable resource of renewable biomass worldwide. For a sustainable management the exploitation of reed is beneficial because the increasing demand for sustainable biomass which presents reed bed areas and wetlands. Knowing the properties of plant biomass obtained from reeds is essential both for the effect on combustion equipment and for the impact on the environment. Brates Lake, situated in Galati, Romania is a natural watershed with reed plantations.ResultsWe used the convolutional neural network method combined with the cropped image techniques represent a powerful tool for high-precision image-based biomass detection in lake areas. The study aimed to investigate the morphological and chemical parameters through SEM–EDX analysis and pH, conductivity, nitrate anion, nitrite anion, total nitrogen, sulphate anion, sulphide anion, phosphate anion concentrations were determined from reed extract. The samples have a moderately acidic reaction pH 4.91–4.98. The number of soluble salts in the reed extract is in the range of 3.24–4.70 g/L, the values are within normal limits, providing the plant with the necessary nutrients.ConclusionsThis is the first time that neural networks are used for the detection and prediction of areas at risk for biodiversity (reduction of water gloss until it disappears, imbalances caused by keeping reeds dry in water) caused by the aggressive and uncontrolled growth of reeds.

Structural studies of Schiff base ligand and its copper complexes: Solvents effect in 1-D polymeric and monomeric copper (II) complexes, computational and sensing studies

The Schiff base ligand (E)-2,4-dibromo-6-(((2-(methylthio)phenyl)imino)methyl)phenol (SL5) and their copper complexes were synthesized. The complex-1 ([Cu (SL5) (CH3COO)]n) and complex-2 ([Cu (SL5) (CH3COO) (CH3OH)]) were obtained by inducing acetic and methanol solvent by post-synthetic modification. Both ligand and metal complexes were characterized by FTIR, SEM, and EDAX analysis. In addition, the photoluminescence behaviour has also been studied. The crystal structures of both ligand and metal complexes were determined by single-crystal X-ray diffraction studies. The structure was solved by direct methods using the SHELXS program and refined by the SHELXL program. The structural changes of ligand in the formation of the metal complexes and the solvent-induced effect of acetic acid and methanol on copper complexes have been studied using crystal structure analysis. The SL5 ligand and complex-2 crystallize in the Monoclinic, P21/n space group and complex-1 crystallize in the Tetragonal, I41/a space group. Complex-1 exhibits six coordinated distorted octahedral geometry. The addition of methanol solvent to complex-1 forms complex-2 and has five coordinated square pyramidal geometry. Complex-1 forms a 1-D coordination polymer chain via Cu1–O3 and it is replaced by the O2–H2‧‧‧O4 interaction with the aid of coordinated methanol solvent in complex-2. The effect of solvents on the coordination sphere directly influences the chelating rings. Complexes-1 exhibits interesting type-II halogen‧‧‧halogen (Br‧‧‧Br) interaction, leading to the formation of tetramer synthons (X4). Halogen-halogen interactions are broken down by adding a methanol solvent, resulting in halogen-hydrogen interactions in complex-2. Crystal structure and quantum computational studies have analyzed the synergetic effect of ligand and solvents on the molecular packing of metal complexes. The Cu(OAc)2SL5 receptor selectively detects sulfide anion in aqueous acetonitrile HEPES buffer solution in the presence of other anions. Further, antibacterial activity has been carried out for MRSA bacteria, and docking studies were carried out for penicillin-binding protein to explore the effect of coordination and solvents.

An Improved Synthesis of Chiral 2,2′-Bipyridine Ligand C3-ACBP Without Column Chromatography

AbstractA method for purifying compounds bearing pyridine structure from Mitsunobu reaction mixtures using zinc chloride and releasing bipyridines from Ullmann coupling reaction mixtures by using sulfide anion for competitively coordinating the copper ion were developed for the facile synthesis of the chiral 2,2′-bipyridine ligand (Ra ,S,S)-C3-ACBP. With these improvements, an improved synthesis of the chiral ligand at a 7 gram scale has been fulfilled in 48% overall yield without column chromatography within 3–4 days.

Influence of NF-κB on the development of oxidative-nitrosative stress in the liver of rats under conditions of chronic alcohol intoxication

Alcohol-related liver disease is the most common cause of liver disease worldwide. The purpose of this work is the establishment of the influence of the transcription factor κB on the development of oxidative-nitrosative stress in the liver of rats under conditions of chronic alcohol intoxication. The experiments were performed on 24 male Wistar rats weighing 180-220 g. The animals were divided into 4 groups of 6 animals: control; animals, which were administered NF-κB inhibitor, namely ammonium pyrrolidinedithio­carbamate (PDTC) at a dose of 76 mg/kg 3 times a week; animals, on which we simulated alcoholic hepatitis and group of combination of alcoholic hepatitis and NF-κB inhibitor. We determined in rat liver homogenate the following biochemical parameters: the activi­ty of NO synthase isoforms, superoxide dismutase and catalase activity, the concentration of malonic dialdehyde, the concentration of peroxynitrite, nitrites and nitrosothiols, concentration of sulfide anion and superoxide anion radical production. Chronic alcohol intoxication led to increased production of reactive oxygen and nitrogen species on the background of decreased antioxidant activity, thus intensifying lipid peroxidation in the liver. Blockade of the transcription factor κB during chronic alcohol intoxication despite an increase in antioxidant activity and decrease of reactive oxygen and nitrogen species production did not ameliorate oxidative damage to the liver. Blockade of activation of nuclear transcription factor κB in rat liver by PDTC reduced the risk of oxidative damage to hepatocytes, but did not reduce the risk of developing nitrosative damage to hepatocytes. Keywords: chronic alcohol intoxication, NF-κB, oxidative-nitrosative stress, PDTC, rat liver

Noncovalent chalcogen and tetrel bonding interactions: Spectroscopic study of halide–carbonyl sulfide complexes

AbstractChalcogen and tetrel intermolecular bonding interactions formed between carbonyl sulfide and halide anions have been studied utilizing a combined experimental and theoretical approach. In particular, high‐level CCSD(T) energetics and experimental anion photoelectron spectroscopy have been used in order to assign the dominant binding motif exhibited in these complexes. Halide anions solvated by multiple carbonyl sulfide molecules have also been investigated in order to ascertain the effect that additional binding partners has on the strength of the noncovalent interactions. The experimental and computational results support the main binding motif of carbonyl sulfide molecules with halide anions being chalcogen bonding, both in dimer complexes and larger solvated complexes. In addition, comparison between the noncovalent interactions formed by halides with carbon disulfide, carbonyl sulfide, and carbon dioxide allows a deeper understanding of noncovalent binding strength in relation to isoelectronic species.Key points Spectroscopic and ab initio characterization of halide–carbonyl sulfide van der Waals complexes bound through chalcogen and tetrel bonding. Detailed insight into chalcogen and tetrel bond strength in the context of changing chemical environments. Effect of increasing solvation on noncovalent binding strength.

Investigation and Determination of Electrochemical Reaction Kinetics in Lithium-Sulfur Batteries with Electrolyte LiTFSI in DOL/DME

A major challenge in the simulation of Li-S batteries is that the electrochemical reaction parameters supplied from the fitting of 0-d or 1-d models depend on the cathode and separator microstructure, so these parameters cannot be used in the design and optimization of material microstructure. The present investigation fits the electrochemical reaction kinetics employing a continuum model taking into account the pore size distribution and tortuosity of cathode and separator in the transport of sulfur molecules and ion species (Li+ ion, electrolyte and sulfide anions) in solvated or desolvated form depending on pore size. Hence, the specified reaction kinetics parameters are independent from the material microstructure. The Li-S redox reaction model includes six redox reactions in the cathode and the lithium redox reaction at the anode. Reactions are assumed to take place in the electrolyte solution rather than in the solid phase of sulfur or lithium sulfide precipitates, where dissolution/precipitation kinetics is modeled especially for the low solubility compounds: sulfur, Li2S and Li2S2. The fitting exercise is conducted based on experimental data of a cyclic voltammetry cycle accompanied by in operando UV–vis spectroscopy. The investigated battery has electrolyte LiTFSI in DOL/DME and no electrocatalysts in any part of the cell.

The geochemistry of zinc and copper stable isotopes in marine hydrothermal brine pools: Perspectives from metalliferous sediments of the Atlantis II Deep, Red Sea

This study provides a zinc and copper stable isotope characterization (δ66Zn, δ68Zn, and δ65Cu) of metalliferous seafloor sediments from the Atlantis II Deep, a hydrothermally influenced brine basin in the Red Sea. Samples collected from box cores that capture the entire stratigraphy in the Deep have δ66Zn and δ65Cu values of −0.31 to 0.34 ‰ (0.02 ‰ median) and − 1.81 to 1.02 ‰ (−0.34 ‰ median) relative to the JMC-Lyon and NIST SRM 976 standards, respectively. These results suggest enrichments of light stable isotopes in sediments compared to the hydrothermal inputs to the basin, which likely overlap the mantle-like isotopic signatures of basalts beneath the Deep. Such shifts to lower δ66Zn and δ65Cu values are consistent with widespread metal sulfide deposition from the brines because sulfide anions preferentially consume the light stable isotopes of zinc and copper. However, this interpretation contrasts with observations in the open ocean, where the fractionation of zinc and copper stable isotopes is strongly influenced by biological utilization and organic matter. Previous studies proposed that metal deposition in the Atlantis II Deep is also driven by adsorption onto iron oxides/hydroxides and their weakly crystalline (Si-)Fe-OOH precursor phases within the brines. However, because this process should accumulate heavy zinc and copper stable isotopes, its influence on isotopic fractionation is likely limited. Controls by metal sulfide precipitation are also indicated by spatial covariations between δ66Zn and concentrations of zinc and copper, that is, δ66Zn values increase whereas metal contents decrease with distance away from hydrothermal venting. Comparable trends are lacking for copper isotopes, perhaps because of additional influence by redox processes or, compared to zinc, a much stronger influence by adsorption onto (Si-)Fe-OOH phases, particularly in areas distal to hydrothermal venting where reduced sulfur could be scarce. Collectively, our results from the Atlantis II Deep indicate that zinc and copper stable isotopes could provide information about base and precious metals deposits from similar paleoenvironments. Firstly, zinc and copper stable isotopes shed light on metal sourcing and accumulation processes. Secondly, mineral precipitation in hydrothermally influenced brine pools produces zinc stable isotope patterns that, at least theoretically, could be of interest in mineral exploration at sub-basin and deposit scales.