A review of gold extraction using noncyanide lixiviants: Fundamentals, advancements, and challenges toward alkaline sulfur-containing leaching agents

Alkaline sulfur-containing lixiviants,including thiosulfate,polysulfides,and alkaline sulfide solutions,stand out as a promising class of alternatives to cyanide because of their low toxicity,high efficiency,and strong adaptability.In this paper,we summarized the research progress and remaining challenges in gold extraction using these noncyanide reagents.After a brief introduction to the preparation method,the transformation process of various sulfur-containing species in alkaline solutions was discussed.Thereafter,some insights into the mechanism of gold leaching in alkaline sulfur-containing solutions were presented from different aspects,including thermodynamics analysis,electrochemical dissolution,and leaching kinetics.Moreover,recent progress in in-situ generation of sulfur-containing anions from gold-bearing sulfide minerals was outlined as well.Gold passivation caused by sulfur species was discussed in particular because it is considered the greatest challenge facing sulfur-containing leaching systems.Alkaline sulfur-containing lixiviants are expected to serve as alternatives in industrial applications of gold extraction,particularly for refractory gold ores containing copper and carbonaceous matter.

Synthesis and Characterization of New Schiff Bases Formed by Condensation of 2,9-Phenathroline-1,10-dialdehyde with Sulfur-Containing Amines

Four new Schiff bases of 1,10-phenanthroline-2,9-dicarboxaldehyde with sulfur-containing amines such as 2-mercaptoaniline, S-alkyl/aryl dithiocarbazates and thiosemicarbazide have been synthesized and characterized by spectroscopic and X-ray crystallographic techniques. A comparative study of the methods of synthesis has been made using both traditional and microwave techniques. A significant reduction in reaction time has been observed when the microwave method was used. In some of the reactions, the yields also increased significantly.

QSPR Study on the Boiling Points of Some Oxygenand Sulfur-containing Organic Compounds

Structural and thermodynamic parameters of 56 oxygen-containing and 56 sulfur- containing organic compounds were computed at the B3LPY/6-311G＊＊ level using density functional theory （DFT） method. Furthermore,the dependent equations between the experimental data of boiling points （Tb） and theoretical parameters were proposed with SPSS12.0 for windows software,whose correlation coefficients R2 are 0.933 and 0.945. These dependent equations were validated by cross-validation method （q2 are 0.923 and 0.929,respectively）. VIF （variance inflation factors） and t-value methods were also used to verify the significance and self-correlationship of each variable. Results indicate that our dependent equation exhibits good prediction ability,and molecular polarizability （α） is the main factor affecting the Tb of oxygen- and sulfur-containing organic compounds. To our interest,obvious dependence could also be found among the oxygen- and sulfur-containing organic compounds＇ experimental data of boiling points （Tb） with R^2 of 0.857.

The Synthesis of New Sulfur-containing Chiral Macrocyclic Ligands

Five new chiral sulfur-containing macrocyclic ligands which can be used in chiral recognition to guests have been synthesized and characterized

An Innovative Method for the Determination of Sulfur-containing Compounds by Vapor Molecular Absorption Spectrometry

Since the most sensitive resonance lines of nonmetallic elements are situated in vacuum ultraviolet region （below 190 nm）, they can not be directly determined with a common AAS instrument covering the spectral range from 190 to 700 nm. The molecular absorption spectrometry is often used for the determination of nonmetallic elements. Syty et al. used vapor molecular absorption spectrometry（VMAS） to determine the sulfur dioxide and sulfide, in which a hydrogen hollow cathode lamp was used as a continuum source to determine SO;at 210 nm and a deuterium arc

Sulfur-containing amino acid methionine as the precursor of volatile organic sulfur compounds in algea-induced black bloom

After the application of methionine, a progressive and significant increase occurred in five volatile organic sulfur compounds （VOSCs）： methanethiol （MESH）, dimethyl sulfide （DMS）, dime^yl disulfide （DMDS）, dimethyl trisulfide （DMTS） and dimethyl tetrasulfide （DMTeS）. Even in the untreated control without a methionine addition, methionine and its catabolites （VOSCs, mainly DMDS） were found in considerable amounts that were high enough to account for the water＇s offensive odor. However, blackening only occurred in two methionine-amended treatments. The VOSCs production was observed to precede black color development, and the reaching of a peak value for total VOSCs was often followed by water blackening. The presence of glucose stimulated the degradation of methionine while postponing the occurrence of the black color and inhibiting the production of VOSCs. In addition, DMDS was found to be the most abundant species produced after the addition of methionine alone, and DMTeS appeared to be the most important compound produced after the addition of methionine＋glucose. These results suggest that methionine acted as an important precursor of the VOSCs in lakes suffering from algea-induced black bloom. The existence of glucose may change the transformation pathway of methionine into VOSCs to form larger molecular weight compounds, such as DMTS and DMTeS.

Sulfur-containing compounds as electrolyte additives for lithium-ion batteries

Originating from“rocking-chair concept”,lithium-ion batteries(LIBs)have become one of the most important electrochemical energy storage technolo-gies,which have largely impacted our daily life.The utilization of electrolyte additives in small quantities(≤5%by wt or vol)has been long viewed as an economical and efficient approach to regulate the properties of electrolyte and electrode–electrolyte interphases and consequently improve the cycling perfor-mance of LIBs.Among all the kinds of electrolyte additives,sulfur-containing compounds have gained significant attention due to their unique features in building stable electrode–electrolyte interphases and protect battery cells from overcharging.In this work,advances and progresses of sulfur-containing addi-tives used in LIBs are overviewed,with special attention paid to the working mechanisms of these electrolyte additives.Particularly,four representative sulfur-containing compounds(i.e.,1,3-propane sultone,prop-1-ene-1,3-sultone,1,3,2-dioxathiolane-2,2-dioxide,and ethylene sulfite)are comparatively dis-cussed concerning their impact on electrode–electrolyte interphases and cell per-formances.Future work on the development of sulfur-containing compounds as functional electrolyte additives is also provided.The present review is antici-pated to be not only a base document to access the status quo in this research domain but also a guideline to select specialized additives and electrolytes for practical applications.

Thiocytochalasins A−D,four sulfur-containing cytochalasans from an endophytic fungus Phoma multirostrata XJ-2-1

Four unprecedented sulfur-containing cytochalasans,thiocytochalasins A−D(1−4),were isolated from an endophytic fungus Phoma multirostrata XJ-2-1.Thiocytochalasins A(1)and B(2)feature a novel 5/6/14/5 tetracyclic scaffold,which are the first examples of cytochalasan containing a thiophene moiety.Thiocytochalasins C(3)and D(4)are epimeric cytochalasan homodimers formed via a thioether bridge.Their structures with absolute configurations were established by detailed analysis of the HRESIMS,NMR,and X-ray crystallography.The plausible biogenetic pathway of 1−4 was postulated.Compounds 3 and 4 exhibited significant cytotoxicity against CT26 cells with IC_(50) values of 0.85 and 0.76µmol/L,respectively.

The intriguing chemistry and biology of sulfur-containing natural products from marine microorganisms(1987-2020)

Natural products derived from marine microorganisms have received great attention as a potential resource of new compound entities for drug discovery.The unique marine environment brings us a large group of sulfur-containing natural products with abundant biological functionality including antitumor,antibiotic,anti-inflammatory and antiviral activities.We reviewed all the 484 sulfur-containing natural products(non-sulfated)isolated from marine microorganisms,of which 59.9%are thioethers,29.8%are thiazole/thiazoline-containing compounds and 10.3%are sulfoxides,sulfones,thioesters and many others.A selection of 133 compounds was further discussed on their structure-activity relationships,mechanisms of action,biosynthesis,and druggability.This is the first systematic review on sulfur-containing natural products from marine microorganisms conducted from January 1987,when the first one was reported,to December 2020.

Sulfur-containing polymer cathode materials: From energy storage mechanism to energy density

Besides lithium-ion batteries, it is imperative to develop new battery energystorage system with high energy density. In conjunction with the developmentof Li-S batteries, emerging sulfur-containing polymers with tunable sulfur-chain length and organic groups gradually attract much attention as cathodematerials. This can avoid the problems that are impeding the development ofthe typical Li-S batteries, such as volume expansion, active material dissolu-tion, shuttle effect, and so on. This review aims to generalize the type ofsulfur-containing polymers and the working principles in Li-S batteries. Thesulfur-containing polymers (R-Sn-R) with different sulfur-chain length (n > 6,n ≤ 2, and 3 ≤ n ≤ 6) are summarized. It also discusses several organic groupssuch as phenyl rings, N-heterocycles, and unique structure with cross-linkednetworks and multi-micropores skeleton. This review also explores other strat-egies of sulfur-containing polymers in the rest of Li-S batteries, providing asummary of the advantages of sulfur-containing polymers, recent develop-ment, in-depth discussion of the mechanism in Li-S batteries, and organicgroup-structure-performance relationship. This review would have guidelinesfor future development of sulfur-containing polymers in Li-S batteries.

Synthesis and self-assembly of phthalocyanines bearing sulfur-containing substituents

Asymmetrically substituted phthalocyanines with sulfur-containing substituents for fabrication of self- assembled monolayers were synthesized. Phthalocyanine 7, bearing a disulfide group, was synthesized from phthalocyanine with a hydroxyl group, which was prepared via mixed condensation of the corresponding substituted phthalonitriles. Phthalocyanine 10, bearing an acetyl protected thiol group, was synthesized through the Pd-catalyzed coupling reaction of an iodophthalocyanine. Their self- assembling behavior on gold substrates was further studied by UV-vis spectroscopy.

Recent advances in the application of sulfinic acids for the construction of sulfur-containing compounds

Sulfur-containing organic compounds display wide applications in the field of materials science,synthetic chemistry,and pharmaceutical industry.Thus,numerous synthetic strategies have been developed for the synthesis of sulfur-containing compounds in synthetic chemistry.In recent years,the utilization of sulfinic acids as versatile synthons has emerged as attractive and powerful approach to access various organosulfur compounds through sulfonylation,sulfinylation or sulfenylation reactions.In this review,we summarized the recent progress in the construction of various sulfur-containing compounds from sulfininc acids.Selected examples of substrates and the related reaction mechanisms are described here.This review intends to provide readers a comprehensive understanding on the synthesis of sulfur-containing molecules from sulfinic acids and provide help for future synthetic research.

Fragment-based discovery of sulfur-containing diarylbenzopyrimidines as novel nonnucleoside reverse transcriptase inhibitors

Two series of sulfur-containing diarylbenzopyrimidines are designed by the fragment combination of a thioacetamide with our previous disclosed DABP 3 and further oxidation.The best compound 6 e with a sulfonyl scaffold displayed EC(50)values of 0.0356μmol/L against WT and 0.0228μmol/L against HIV K103 N mutant strain.More pronounced,it had a lower cytotoxicity(CC(50)=99.6μmol/L),higher selectivity index(SIWT=2799,SIK103 N=4375)and better calculated logarithm of the octanol-water partition coefficient(cLogP)than the lead compound 3.Molecular docking and dynamics provided the binding modes of these compounds with reve rse transcriptase,explaining their activity.Collectively,the new compounds could be candidates for anti-HIV drug discovery.

Carbon–sulfur bond formation via photochemical strategies: An efficient method for the synthesis of sulfur-containing compounds

The development of green and convenient methods for C–S bond formation has received significant attention because C–S bond widely occurs in many important pharmaceutical and biological compounds.Recently, visible-light photoredox catalysis has been established as an efficient and general tool for the construction of C–C and C-heteroatom bonds. In this review, we have focused on the research on recent advances in C–S bond formation via visible-light photoredox catalysis, and the growing opportunities they present to the construction of complex chemical scaffolds for applications encompassing bioactive molecules synthesis, synthetic methodology development, and sulfur-containing drugs. We hope that this review will provide chemists with a synthetic tool that will open the door to further development of organsulfur chemistry.

Microbial reduction of sulfur-containing ketones by Geotrichum sp.

Bioreduction of some β-carbonyl phenyl sulfides, sulfoxides and sulfones (1, 3, 5, 8, 11 and 13) by Geotrichum sp. was studied. Reduction of β-carbonyl phenyl sulfoxides (5 and 8) gave anti-Prelog sulfoxide alcohols. (S,Ss)-3-Chloro-1-phenylsulfinylpropan-2-ol (9) WBP obtained in high yield with 95% e. e. after recrystallization from methylene chloride petroleum ether.

The role of the sulfur 3d orbitals in bond formation in sulfur-containing compounds

The role of the sulfur 3d orbitals in bond formation is discussed by taking into account the influence of the environment on the orbitals of the sulfur atom in the molecules. The ca cula- tion results of a series of prototype molecules containing sulfur such as SF_2, SF_4, NSF_3, SF_1, H_2S are reported. It is convincingly shown that in highly electronegative environment the energy levels of the sulfur 3d orbitals are reduced to the vicinity of those of the ligand valence orbitals and their spatial distributions are contracted to the bonding area, and therefore they can participate in bond formation to a certain extent, which is enhanced by the formation of the d-p π back bonds. It seems that the result reported in this paper is helpful for the solution of the long-standing debate about the sulfur 3d orbital participation in bond formation.

Selenium-doped cathode materials with polyaniline skeleton for lithium-organosulfur batteries

Sulfur-containing polymer(SCP)is considered as an outstanding cathode material for lithium-sulfur batteries.However,undesirable soluble polysulfides may shuttle in electrolyte,concluding long-chain Li_(2)S_(n)(n>4)and short-chain Li2Sn(n≤4),as well as the sluggish conversion kinetics are yet to be solved to enhance the performance of lithium-sulfur batteries.Here Se-doped sulfurized polyaniline with adjusted sulfur-chain-S_(x)-(x≤6)contribute to ensure the absence of long-chain polysulfides,and the skeleton with quinoid imine can endow strongly adsorption towards short-chain polysulfides by the reversible transition between deprotonated/protonated imine(-NH^(+)=and-N=),which offer double insurance against suppressing“shuttle effect”.Furthermore,Se atoms are doped into sulfurized polysulfides to accelerate the redox conversion and take a frontier orbital theory-oriented view into catalytic mechanism.Se-doped sulfurized polyaniline as active materials for lithium-organosulfur batteries delivers good electrochemical performance,including high rate,reversible specific capacity(680 mA h g^(-1)at 0.1 A g^(-1)),and lower capacity decay rate only of 0.15%with near 100%coulomb efficiency during long-term cycle.This work provides a valuable guiding ideology and promising solution for the chemistry-oriented structure design and practical application for lithium-organosulfur batteries.

Determination of sulfur anions by ion chromatography-postcolumn derivation and UV detection

A novel method for determination of formaldehyde sulfoxylate, sulfite, thiocyanate, and thiosulfate in foodstuffs by ion chromatography separation with postcolumn derivation and UV detection has been developed. All species are separated at Dionex IonPac AG22A and AS22A with mobile phase of a mixture of 4.5 mmol/L sodium carbonate and 0.8 mmol/L sodium bicarbonate at a flow-rate of 1.0 mL/min. The postcolunm derivation solution was 0.24% iodine in 0.2% phosphate acid and the detection wavelength was set at 288 nm. The detection limits （LOD, signal-to-noise ratio of 3） of formaldehyde sulfoxylate, sulfite, thiocyanate, and thiosulfate were 0.004, 0.006, 0.006, and 0.007 mg/L, respectively. Within-day relative standard deviations （RSD, n = 10） of formaldehyde sulfoxylate, sulflte, thiocyanate, and thiosulfate were 3.24%, 3.76%, 2.68%, and 2.07%, respectively. The recoveries of the four anions were in the range of 67.2-116.5%.

Involvement of sulfur assimilation in the low β subunit content of soybean seed storage protein revealed by comparative transcriptome analysis

The β subunit of soybean [Glycine max (L.) Merr.] seed storage protein is of great significance in sulfur-containing amino acid balance and soybean processing properties. The objective of this study was to elucidate the relationship between the β subunit and sulfur-containing amino acid composition, and the potential regulatory mechanism. The β subunit was independently accumulated in comparison with other major subunits (α/α′, acidic, basic, and A3) during seed filling, and a low level of β subunit content (BSC) was formed during the accumulation process. In low-BSC mature seeds, crude protein, oil content, and fatty acid composition were not changed, but sulfur-containing amino acids (Cys + Met) in the low- BSC seeds increased significantly (by 31.5%), suggesting that an internal regulatory mechanism within seed might be responsible for the rebalance of seed protein composition and that sulfur assimilation might be deeply involved in β subunit accumulation. Transcriptomic analysis revealed that genes involved in anabolism of cysteine, methionine, and glutathione were up-regulated but those involved in the catabolism of these compounds were down-regulated, suggesting a relationship between the elevation of methionine and glutathione and low BSC. Our study sheds light on seed composition in low BSC lines and on the potential molecular regulatory mechanism of β subunit accumulation, broadening our understanding of soybean seed protein synthesis and its regulation.

Specialized metabolites as versatile tools in shaping plant-microbe associations

Plants are rich repository of a large number of chemical compounds collectively referred to as specialized metabolites.These compounds are of importance for adaptive processes including responses against changing abiotic conditions and interactions with various co-existing organisms.One of the strikingly affirmed functions of these specialized metabolites is their involvement in plants’life-long interactions with complex multi-kingdom microbiomes including both beneficial and harmful microorganisms.Recent developments in genomic and molecular biology tools not only help to generate well-curated information about regulatory and structural components of biosynthetic pathways of plant specialized metabolites but also to create and screen mutant lines defective in their synthesis.In this review,we have comprehensively surveyed the function of these specialized metabolites and discussed recent research findings demonstrating the responses of various microbes on tested mutant lines having defective biosynthesis of particular metabolites.In addition,we attempt to provide key clues about the impact of these metabolites on the assembly of the plant microbiome by summarizing the major findings of recent comparative metagenomic analyses of available mutant lines under customized and natural microbial niches.Subsequently,we delineate benchmark initiatives that aim to engineer or manipulate the biosynthetic pathways to produce specialized metabolites in heterologous systems but also to diversify their immune function.While denoting the function of these metabolites,we also discuss the critical bottlenecks associated with understanding and exploiting their function in improving plant adaptation to the environment.