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Rapid organic synthesis in reduced steps achieves cost-effectiveness by decreasing both the time and amount of material used to complete a reaction. This study explored the use of microwaves as an alternate energy source to drive the synthesis of thiols from their corresponding halides using potassium thioacetate as an inexpensive thiol source. Departing from previous synthetic routes, which require multiple steps and intermediate product isolation, the reported one-pot synthesis allows for direct conversion of the halide starting material to the corresponding thiol. This method works for alkyl halides, including straight chain, branched, or cyclic. This improved methodology was 6 to 24 times faster than previously reported synthetic methodologies and produced isolated yields of > 90%, a 1.25-fold improvement. [ABSTRACT FROM AUTHOR]

Background. The literature data on the synthesis and properties of mixed-metal complexes of 3d metals with ammonium vanadate and 5-amino-2-mercaptobenzimidazole is limited. Thus, the synthesis and study heterometallic compounds allowed elaborating new aspects of coordination chemistry. Purpose. Elaboration of the synthesis method for mixed-metal complexes of Mn (II), Co (II), Ni (II), Cu (II) and Zn nitrates with ammonium vanadate and 5-amino-2-mercaptobenzimidazole (L) and study of their composition and structure with modern physical and chemical methods. Methodology. A technique for synthesis of mixed-metal complex compounds has been elaborated. For their synthesis, an alcoholic solution of the ligand (molar ratio M: M: L=1: 2: 2) was added to solution of ammonium vanadate and metal chlorides, pH 8. The reaction had been carried out at heating for 40 min. The coordinating competitive donor centers, the electronic and geometric structure of the ligand molecule were investigated by quantum-chemical calculations using the DFT / V3LIP / LanL2DZ method in the Gaussian09 software package. The composition and structure of the synthesized mixed-metal complex compounds were investigated by the methods of elemental, thermal analysis and FTIR- spectroscopy. Originality. A procedure has been developed for synthesis of mixed-metal complex compounds: Mn (II), Co (II), Ni (II), Cu (II), Zn nitrates with ammonium vanadate and 5-amino-2-mercaptobenzimidazole. It was found that in complexation reactions the ligand molecule is coordinated through the nitrogen atom with the negative value of the effective partially localized charge. Findings. The data on coordinating competitive donor centers, the electronic and geometric structure of the ligand molecule. [ABSTRACT FROM AUTHOR]

Highlights • Castor oil-modified bio-mercaptan is used to prepare UV-cured flame-retardant coatings. • The pencil hardness of castor oil-based coating has improved to H grade. • P, S and Si in the coating have a synergistic flame retardant effect. • The coated wood of F4 remains the wood tracheid basic skeleton after combustion. • Bio-mercaptan can reduce the maximum degradation rate of the coatings. Abstract In this paper, a multifunctional castor oil based bio-mercaptan (abbrev. CO SH) was synthesized by esterification between castor oil (abbrev. CO) and 3-mercaptopropionic acid (MPA). In addition, [(6-Oxido-6H-dibenz [c,e][1,2] oxaphosphorin-6-yl) methyl] butanedioic acid (DDP) and allyl glycidyl ether (AGE) were used to synthesize the organic phosphorus flame retardant containing a double bond of allyl ether DDP-AGE (abbrev. DA) via a ring-opening reaction. The synergistic flame-retardant UV-cured coating containing phosphorus (P), silicon (Si) and sulfur (S) was prepared on wood surface with varying molar content of CO SH, DA and 2,4,6-trimethyl-2,4,6-trivinylcyclotrisilazane (TTC) via the thiol-ene click reaction. The results show that when the molar ratio of CO SH, DA and TTC is 5: 3: 3, the UV-cured coated wood samples pass the vertical UL-94 V-0 rating; the limiting oxygen index (LOI) value can reach 27.52%; the second peak of heat release rate (P2HRR) and the second smoke production rate peak (P2SPR) of the coated wood samples can be effectively suppressed, while the total heat release (THR) of 16.99 MJ/m2 is much lower than other samples and the total smoke production (TSP) is equivalent to that of uncoated wood sample; the final char residue rate can reach 14.41% during the cone calorimetry (CONE) tests. Moreover, the thermogravimetric analysis (TGA) demonstrates that CO SH promotes the degradation of films at a lower temperature, while it reduces the maximum degradation rate and delays the decomposition process simultaneously. Besides, the scanning electron microscope (SEM) shows that the coated wood internal tracheid basic skeleton remains basically intact and the char layer tends to exhibit a more compact morphology after the CONE tests if the wood is coated following the molar ratio of CO SH, DA and TTC of 5: 3: 3. Energy dispersive spectrometer (EDS) was used to compare the content of C, O, N, P, Si and S of the char layers formed by the coatings on the surface of coated wood samples after CONE tests, which addresses the synergistic flame retardance of P, S and P, Si. [ABSTRACT FROM AUTHOR]

Due to the normal polarity preferences, arenes form stable complexes with thiols through S−H⋅⋅⋅π interaction and direct dehydrogenative aryl C−S coupling is usually restricted. We report here an umpolung based one pot and direct C−S coupling approach under metal free and mild condition. Electrophile sulfenium ions were generated in situ from thiols using iodine(III) reagent PhI(OAc)2 (PIDA) and subsequently used for aromatic electrophilic substitution (EArS) to synthesize diaryl sulfides. Also by using of appropriate amount of PIDA, cascaded synthesis of C−S and S=O bonds led to aryl sulfinyl arenes in one pot. Covalent self‐sorting or competitive experiments further confirmed the involvement of sulfenium ion in the EArS. [ABSTRACT FROM AUTHOR]

Despite the growing application of tetrazine bioorthogonal chemistry, it is still challenging to access tetrazines conveniently from easily available materials. Described here is the de novo formation of tetrazine from nitriles and hydrazine hydrate using a broad array of thiol‐containing catalysts, including peptides. Using this facile methodology, the syntheses of 14 unsymmetric tetrazines, containing a range of reactive functional groups, on the gram scale were achieved with satisfactory yields. Using tetrazine methylphosphonate as a building block, a highly efficient Horner–Wadsworth–Emmons reaction was developed for further derivatization under mild reaction conditions. Tetrazine probes with diverse functions can be scalably produced in yields of 87–93 %. This methodology may facilitate the widespread application of tetrazine bioorthogonal chemistry. [ABSTRACT FROM AUTHOR]

Synthesis of 1-[(2,2-dimethyl-1,3-dioxolan-4-yl)methyl]-1H-indole- -2,3-dione (10) was achieved by coupling 1H-indole-2,3-dione (16) with (R)- -(2,2-dimethyl-1,3-dioxolan-4-yl)methyl 4-methylbenzenesulfonate (15) in the presence of sodium hydride in dry N,N-dimethylformamide at room temperature in a closed Erlenmeyer flask. Condensation of 10 with hydrazinecarbothioamide in water afforded the thiosemicarbazone derivative 17; its subsequent cyclization with potassium carbonate in water gave the corresponding thione 18 in good yield. The 3-allylthio and 3-benzylthio derivatives 20 and 21 were also prepared by alkylating thiol 19 with alkyl halides in aqueous sodium hydroxide or coupling of 3-(allylthio/benzylthio)-5H-1,2,4-triazino[5,6-b]indoles (23 and 24) with compound 15 in NaH/DMF. Compound 20 was isomerized to a mixture of geometrical isomers (E/Z)-5-[(2,2-dimethyl-1,3-dioxolan-4-yl)- methyl]-3-(prop-1-en-1-ylthio)-5H-1,2,4-triazino[5,6-b]indoles (25 and 26), evidenced by their 1H- and 13C-NMR spectra taken in deuterodimethyl sulfoxide. Structural elucidation of the synthesized compounds was realized using FT-IR, 1H-NMR, 13C-NMR, mass spectrometry and elemental analysis. The newly synthesized compounds were found to possess moderate inhibitory activity against the fungus Candida albicans compared to clotrimazole as reference control. Compounds 10, 17, 19, 20, 21, 23 and 24 had mean growth inhibition zones (IZ) and minimal inhibitory concentrations (MIC) in the range of 12-15 mm and 31.25-200 μg mL-1, respectively, with inhibition levels in the range 70.58-88.23 %. Compound 19 exhibited moderate activity against Gram-positive bacteria Staphylococcus aureus relative to imipenem as the standard drug. All compounds were inactive against Escherichia coli and Pseudomonas aeruginosa. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Direct synthesis of PMMA microspheres with clickable double bonds on the surface. • A RAFT-assisted dispersion photopolymerization process was employed. • Photo-click reaction of the obtained microspheres with thiolated biotin. • Immobilizing FITC-SAv via the specific adsorption of biotin to streptavidin. Abstract Introducing clickable groups onto polymer microspheres allows the microspheres to be facilely functionalized via a click reaction. In this report, we have synthesized monodisperse PMMA microspheres with clickable double bonds on the surface by one-step RAFT-assisted dispersion photopolymerization using a cyclohexyl-containing macro-RAFT agent as a stabilizer. This macro-RAFT agent, named P(THPAA- b -AA)-TTC, was synthesized by RAFT-mediated block copolymerization of a cyclohexyl-containing monomer (THPAA, obtained by esterification of cis-1,2,3,6-tetrahydrophthalic with 2-hydroxyethyl acrylate) and acrylic acid. The obtained microspheres were analyzed by 1H NMR and Iodometric method, indicating that the content of carbon double bonds on the microspheres increased with increasing the amount of P(THPAA- b -AA)-TTC in the polymerization feed. We then used a thiolated biotin to perform the photo-click reaction with the cyclohexene double bond on the microspheres, thereby attaching the biotin unit onto the microspheres. The biotinylated PMMA microspheres were found to be able to effectively immobilize fluorescein isothiocyanate streptavidin (FITC-SAv) via the specific adsorption of biotin to streptavidin, and thus exhibited clear fluorescence under confocal microscope. This study provides a convenient and feasible way to prepare surface-functionalized microspheres, which has great potential in biological applications as well as other fields. [ABSTRACT FROM AUTHOR]

Abstract A pair of stable isotope labeling (SIL) reagents, N -(4-(carbazole-9-yl)-phenyl)- N -maleimide (NCPM-d 0) and its heavy analogue NCPM-d 2 , were used for labeling thiol-containing drugs. On basis of SIL, a global isotope internal standard quantitative method for the detection of five thiol-containing drugs by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was developed. The NCPM-d 0 and NCPM-d 2 can easily label thiol-containing drugs under mild conditions within 10 min at 40 °C. The NCPM-d 0 and NCPM-d 2 labeled thiol-containing drugs can generate two characteristic product ions (m / z at 372.5 and 374.5) under collision induced dissociation, respectively, which is used to establish the multiple reaction monitoring (MRM) based detection. The NCPM labeling combined with MRM analysis not only allowed trace detection of thiol-containing drugs due to the extremely high sensitivity, but also efficiently corrected the matrix effects during HPLC-MS/MS and the instrument fluctuation in the MS/MS signal intensity. The detection sensitivities of thiol-containing drugs improved by 14.5–650.5-fold due to NCPM-labeling, while the matrix and ion suppression effects were markedly minimized by the SIL strategy. The limits of detection (LODs) and the limits of quantitation (LOQs) were in the range 10.0–15.0 ng·mL−1 and 31.0–50.0 ng·mL−1, respectively. The proposed method was used for the simultaneous determination of five thiol-containing drugs in plasma samples with satisfactory recoveries in the range of 95.0–97.5%. Highlights • A stable isotope labeling strategy for analyzing thiol-containing drugs has been developed. • A pair of SIL reagents NCPM-d 0 and NCPM-d 2 were used to label thiol-containing drugs. • The detection sensitivities of thiol-containing drugs improved by 14.5–650.5-fold. • The proposed method was successfully applied to pharmacokinetic study of captopril. [ABSTRACT FROM AUTHOR]

Oxidative stress is considered to be one of the molecular changes that are the underlying causes of tinnitus. The aim of this study was to investigate the dynamic thiol/disulphide homeostasis as a new oxidative stress parameter in tinnitus patients as well as to investigate the lipid hydroperoxide (LOOH), total antioxidant status (TAS), total oxidant status (TOS) and oxidative stress index (OSI) parameters and compare the results with the results of the healthy control group. A prospective controlled trial was performed on tinnitus patients in Harran University hospital. A total of 70 subjects, including 35 tinnitus patients and 35 healthy individuals participated in this study. Their total thiol, native thiol levels and LOOH, TAS, TOS levels were measured in plasma of all tinnitus patients and healthy volunteers participants. TOS and OSI levels were significantly increased, and TAS levels were significantly lower in the patient groups compared with the control group (p < 0.01). Native thiol levels and Native thiol/total thiol ratios were significantly lower in the tinnitus group compared to the control group (p < 0.01). Disulphide level and disulphide/native thiol and disulphide/total thiol ratios were significantly higher in the patients (p < 0.01). Also, LOOH ratios were significantly higher in the tinnitus group (p < 0.01). The results of this study reveal that in tinnitus cases, the oxidative stress and antioxidant enzyme imbalance were more significant than in healthy control group. The nature of the relationship between oxidative stress and tinnitus should be clarified with larger studies. [ABSTRACT FROM AUTHOR]

A combination of ring‐opening polymerization (ROP) and reversible addition of fragmentation chain transfer (RAFT) polymerization techniques was successfully employed for the synthesis of a novel pH‐ and glucose‐responsive thiol‐end‐capped ABC triblock copolymer, namely, poly(acrylic acid)‐block‐poly(vinylphenylboronic acid)‐block‐poly(ε‐caprolactone)–SH (PAA‐b‐PVPBA‐b‐PCL‐SH). The synthesized triblock copolymer was characterized using Fourier transform infrared (FTIR) and proton nuclear magnetic resonance (1H NMR) spectroscopies. The molecular weights of each segment in the synthesized triblock copolymer were calculated using both gel permeation chromatography (GPC) and 1H NMR spectroscopy. The self‐assembly behavior of the fabricated triblock copolymer under various pHs as well as in the presence of glucose were investigated using dynamic light scattering (DLS) measurement. The PAA‐b‐PVPBA‐b‐PCL‐SH triblock copolymer was conjugated with gold nanoparticles (GNPs). In addition, the morphologies of GNPs, PAA‐b‐PVPBA‐b‐PCL‐SH triblock copolymer, and GNPs@polymer were observed using transmission electron microscopy (TEM). As the results, the fabricated GNPs@Polymer can be employed as drug delivery system and micellar glucose biosensor. [ABSTRACT FROM AUTHOR]

Siegesbeckia orientalis L. is a promising species for cadmium (Cd) phytoextraction with large biomass and fast growth rate, while little information about their intracellular mechanisms involved in Cd tolerance and detoxification has been explored. A soil pot experiment with total target Cd concentrations of 0, 10, 50, 100, and 150 mg kg−1 were designed to investigate the subcellular distribution, chemical forms and thiol synthesis characteristics of Cd in S. orientalis. More than 90% of Cd was bound to the soluble fractions (48.4-76.5%) and cell walls (19.9-46.3%). Increasing soil Cd concentrations enhanced Cd sequestration into the cell walls. Most of the Cd (69.8-82.7%) in the plant organ was mainly in the forms of pectate and protein integrated Cd and undissolved Cd phosphate, while a minor portion (6.8-20.9%) was in the forms of the inorganic Cd and the water soluble Cd. Nonprotein thiols and phytochelatins significantly increased with increasing soil Cd treatment levels, while glutathione concentrations had no obvious change trends. Therefore, intracellular detoxification mechanisms of Cd in S. orientalis mainly rely on formation of less toxic Cd chemical forms, store of a large amount of Cd in cell wall and synthesis of thiol compounds. [ABSTRACT FROM AUTHOR]

Abstract: Highly toxic heavy metal ions such as mercury ions (Hg2+) are a great threat to human life and the environment. Developing new strategies and materials to remove the toxic heavy metal ions has attracted more and more attentions. Herein a facile self‐protection synthesis of thiol‐based nanoporous adsorbents for efficient mercury removal via a polymerization‐cutting strategy is reported. The direct free‐radical polymerization of divinyl disulfide derivative and subsequently cutting off the disulfide linkage, without post‐synthesis or modification, can give rise to an exceptionally high density of thiol chelating sites. Moreover, the resultant thiol‐based nanoporous adsorbents (NAs‐SH) exhibit a high saturation uptake capacity (1240 mg g−1) and reused ability for mercury removal from water solution. The proposed polymerization‐cutting strategy may provide an alternative and cost‐effective method for the design and synthesis of various efficient nanoporous adsorbents at large scale in the future. [ABSTRACT FROM AUTHOR]

In order to address the increasingly severe pollution issue caused by heavy metals, activated carbon-based absorbents have gained considerable attention. Herein, two novel adsorbents, amino-functionalized activated carbon (N-AC) and thiol-functionalized activated carbon (S-AC), were successfully synthesized by stepwise modification with tetraethylenepentamine (TEPA), cyanuric chloride (CC) and sodium sulfide. The pristine and synthesized materials were characterized by BET analysis, SEM, FTIR spectroscopy, elemental analysis and zeta-potential analyzer. Meanwhile, their adsorption properties for Cd 2+ and Pb 2+ and the effects of various variables on the adsorption processes were systematically investigated. The findings confirmed that amino-groups and thiol-groups endowed the AC with a strong affinity for metal ions and that the pH of solution affected the uptake efficiencies of the adsorbents by influencing their surface charges. Furthermore, six isotherm models (Langmuir, Freundlich, Temkin, Dubinin-Radushkevich, Sips and Redlich-Peterson) and four kinetic models (pseudo-first-order, pseudo-second-order, Intra-particle diffusion and Elovich) were applied to interpret the adsorption process at three different temperatures (288 K, 298 K and 308 K). The results indicated that temperature played an important role and that the rate-limiting step was chemosorption. A better fit for all adsorption systems was obtained with Langmuir model, with the maximum adsorption capacities at 298 K of 79.20 mg Cd 2+ /g and 142.03 mg Pb 2+ /g for N-AC, 130.05 mg Cd 2+ /g and 232.02 mg Pb 2+ /g for S-AC, respectively. Subsequently, the thermodynamic parameters revealed the nature of the adsorption was endothermic and spontaneous under the experimental condition. The possible adsorption procedures and the underlying mechanisms comprising physical and chemical interactions were proposed. Moreover, the as-synthesized adsorbents exhibited excellent regeneration performance after five adsorption/desorption cycles. The overall results demonstrated that both N-AC and S-AC could be the promising efficient candidates for removing Cd 2+ and Pb 2+ from contaminated water. [ABSTRACT FROM AUTHOR]

In this report, we describe the radiosynthesis of a new thiol-targeting prosthetic group for efficient radioactive iodine labeling of biomolecules. Radioiodination using the precursor 3 was performed to obtain 125 I-labeled tetrazole 4b with high radiochemical yield (73%) and radiochemical purity. Using the radiolabeled 4b , a single free cysteine containing peptide and human serum albumin were labeled with 125 I in modest-to-good radiochemical yields (65–99%) under mildly reactive conditions. A biodistribution study of [ 125 I] 7 in normal ICR mice exhibited lower thyroid uptake values than those of 125 I-labeled human serum albumin prepared via a traditional radiolabeling method. Thus, [ 125 I] 7 could be employed as an effective radiotracer for molecular imaging and biodistribution studies. The results clearly demonstrate that 4b has the potential to be effectively implemented as a prosthetic group in the preparation of radiolabeled biomolecules. [ABSTRACT FROM AUTHOR]

Abstract: We report a new method herein coined SP‐CLipPA (solid‐phase cysteine lipidation of a peptide or amino acid) for the synthesis of mono‐S‐lipidated peptides. This technique utilizes thiol–ene chemistry for conjugation of a vinyl ester to a free thiol of a semiprotected, resin‐bound peptide. Advantages of SP‐CLipPA include: ease of handling, conversions of up to 91 %, by‐product removal by simple filtration, and a single purification step. Additionally, the desired lipidated products show high chromatographic separation from impurities, thus facilitating RP‐HPLC purification. To showcase the utility of SP‐CLipPA, we synthesized a potent calcitonin gene‐related peptide (CGRP) receptor antagonist peptide in excellent yield and purity. This peptide, selected from a series of lipidated analogues of CGRP8–37 and CGRP7–37, has potential for the treatment of migraine. [ABSTRACT FROM AUTHOR]

Abstract: In protein or peptide chemistry, thiols are frequently chosen as a chemical entity for chemoselective modification reactions. Although it is a well‐established methodology to address cysteines and homocysteines in aqueous media to form S−C bonds, possibilities for the chemoselective formation of asymmetric disulfides have been less approached. Focusing on bioreversibility in conjugation chemistry, the formation of disulfide bonds is highly desirable for the attachment of thiol‐containing bioactive agents to proteins or in cross‐linking reactions, because disulfide bonds can combine stability in blood with degradability inside cells. In this Concept article, recent approaches in the field of activating groups for thiol moieties incorporated in peptide and polymer materials are highlighted. Advantageous combinations of stability during synthesis of the material with high reactivity towards thiols are explored focusing on simplification and prevention of side reactions as well as additional deprotection and activation steps prior to disulfide formation. Moreover, applications of this chemistry are highlighted and future perspectives are envisioned. [ABSTRACT FROM AUTHOR]

Aim The purpose of this study was to develop a novel thiolated starch polymer with improved mucoadhesive properties by conjugation of cysteamine to starch as a natural polymer of restricted mucoadhesive properties. Methods Aldehyde substructures were integrated into starch via oxidative cleavage of vicinal diols by increasing amounts of sodium periodate followed by covalent attachment of cysteamine to oxidized starch via reductive amination. Thiol groups were quantified via Ellman’s reaction and their impact on mucoadhesion was analyzed by rheological investigations, the rotating cylinder method and tensile studies on porcine mucosa. Results The total amount of immobilized thiol groups revealed a correlation between degree of oxidation and thiolation. Modified starch demonstrated an up to 1.66-fold increase in water uptake in comparison to native starch. Modification of starch resulted in greatly improved cohesive properties and improvement in mucoadhesion. Rheological investigations revealed a 2- to 4-fold rise in viscosity of mucus. Tensile studies revealed a linear correlation between degree of oxidation/thiolation and enhancement of maximum detachment force and total work adhesion. Conclusion In terms of these results, thiolated starch is a new, promising, polymer in the field of mucoadhesive drug delivery systems. [ABSTRACT FROM AUTHOR]

ABSTRACT: A multiblock copolymer consisting of hard (poly(arylene ether sulfone)) and soft (poly(alkyl disulfide)) segments was successfully synthesized by oxidative coupling of the corresponding thiol‐terminated oligomers. Its structure was confirmed by 1H and 13C NMR spectroscopy. The GPC data (Mw = 82,000, Mw/Mn = 2.7) and inherent viscosity (0.67 dL g−1) indicated the formation of a high‐molecular‐weight multiblock copolymer, while AFM and DSC indicated a microphase‐separated morphology. Tensile testing of the multiblock copolymer films showed a large elongation at break, which is characteristic of microphase‐separated hard/soft multiblock copolymers. Over 90% of the elongation at break of damaged samples (notched or cut) was recovered by UV irradiation. The elongation recovery was proportional to the UV irradiation energy, and the high recovery was achieved by relatively weak irradiation (<170 J cm−2). The high content of disulfide bonds in the multiblock copolymer resulted in a lower self‐healing energy. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 1358–1365 [ABSTRACT FROM AUTHOR]

Abstract: The use of adhesives for fracture fixation can revolutionize the surgical procedures toward more personalized bone repairs. However, there are still no commercially available adhesive solutions mainly due to the lack of biocompatibility, poor adhesive strength, or inadequate fixation protocols. Here, a surgically realizable adhesive system capitalizing on visible light thiol–ene coupling chemistry is presented. The adhesives are carefully designed and formulated from a novel class of chemical constituents influenced by dental resin composites and self‐etch primers. Validation of the adhesive strength is conducted on wet bone substrates and accomplished via fiber‐reinforced adhesive patch (FRAP) methodology. The results unravel, for the first time, on the promise of a thiol–ene adhesive with an unprecedented shear bond strength of 9.0 MPa and that surpasses, by 55%, the commercially available acrylate dental adhesive system Clearfil SE Bond of 5.8 MPa. Preclinical validation of FRAPs on rat femur fracture models details good adhesion to the bone throughout the healing process, and are found biocompatible not giving rise to any inflammatory response. Remarkably, the FRAPs are found to withstand loads up to 70 N for 1000 cycles on porcine metacarpal fractures outperforming clinically used K‐wires and match metal plates and screw implants. [ABSTRACT FROM AUTHOR]

In this study, S-, S,S- and S,O-substituted novel nitrodiene compounds were synthesized. Cyclization products were formed when difunctional nucleophiles were used. The stereoisomerism of a heterocyclic nitrodiene is discussed with the help of XRD studies. The structures of all compounds were characterized by spectroscopic methods (FT-IR, 1H NMR, 13C NMR, 19F NMR, MS) and microanalysis. [ABSTRACT FROM AUTHOR]

Two ‘turn on’ TCF-based fluorescence probes were developed for the detection of biological thiols (TCF-GSH and TCFCl-GSH). TCF-GSH was shown to have a high sensitivity towards glutathione (GSH) with a 0.28 μM limit of detection. Unfortunately, at higher GSH concentrations the fluorescence intensity of TCF-GSH decreased and toxicity was observed for TCF-GSH in live cells. However, TCFCl-GSH was shown to be able to detect GSH at biologically relevant concentrations with a 0.45 μM limit of detection. No toxicity was found for TCFCl-GSH and a clear ‘turn on’ with good photostability was observed for the exogenous addition of GSH, Cys and HCys. Furthermore, TCFCl-GSH was used to evaluate the effects of drug treatment on the levels of GSH in live cells. [ABSTRACT FROM AUTHOR]

Radical decyanation of aliphatic nitriles was achieved in the presence of NaBH4 and a thiol. The reaction proceeds via a radical mechanism involving borane radical anion addition to nitrile to form an iminyl radical, which undergoes carbon–carbon cleavage. Reductive radical addition to acrylonitrile is followed by decyanation to give a two-carbon homologated product in a net radical ethylation reaction. [ABSTRACT FROM AUTHOR]

Summary: Background: Oxidative stress (OS) has an important effect on the pathogenesis of atopic dermatitis (AD). Thiols are antioxidants that regulate intracellular redox metabolism and protect keratinocytes against OS damage in the stratum corneum. Aim: To investigate dynamic thiol‐disulphide homeostasis (dTDH) as a novel OS parameter in children with AD, and its relationship with disease severity and chronicity. Methods: Severity of AD was determined by using the instruments SCORing Atopic Dermatitis (SCORAD) and Eczema Area And Severity Index (EASI) upon enrolment in the study (SCORAD1 and EASI1) and after 1 year (SCORAD2 and EASI2). Native thiol, total thiol and disulphide levels were measured as novel OS parameters, and the ratios of disulphide/native thiol, disulphide/total thiol and native/total thiol were calculated as dTDH. Results: In the AD group, the serum disulphide level and the ratios of disulphide/native thiol and disulphide/total thiol were significantly lower than in healthy controls (P = 0.01, P < 0.01 and P < 0.01, respectively). There was no significant association between OS parameters and disease severity (P > 0.05). SCORAD2 and EASI2 were positively correlated with disulphide/native thiol ratio (r = 0.29, P < 0.03 and r = 0.35, P < 0.01, respectively), whereas they were negatively correlated with the native/total thiol ratio (r = −0.30, P = 0.02 for both). Conclusions: Both OS and impaired dTDH were found to be related to childhood AD. None of the OS parameters was associated with AD severity. dTDH is a possible diagnostic tool to predict AD chronicity. [ABSTRACT FROM AUTHOR]

Abstract: A simple, efficient and catalyst‐free sulfenylation of imidazoheterocycles with sulfonyl hydrazides has been developed in water under additive free condition. This method is highly regioselective, and the corresponding thio products were obtained in good to excellent yields. Experimental studies were indicative of the formation of sufonothioate intermediates from sufonyl hydrazides as the active thiol carrier for this transformation. [ABSTRACT FROM AUTHOR]

We report a facile approach to tailor the wettability of ligno-cellulosic substrates via photo-induced thiol-yne click coupling. First, cellulosic surfaces were functionalized with 4-pentynoic acid to introduce terminal alkyne moieties for the subsequent photo-induced coupling in heterogeneous phase. Next, the (primed) surfaces were reacted with various thiol-containing molecules to systematically tailor the surface energy. Finally, the method was applied to nanocellulose films and paper to develop micro-patterned surfaces via UV lithography, endowing the substrates with thin hydrophilic channels (~ 250 μm thickness) and hydrophobic boundaries between neighboring water droplets, as small as 100 μm in width. Overall, we propose thiol-click as a facile method toward spatially-resolved wetting that enables paper-based electronics in smart labels and point-of-care bioplatforms. [ABSTRACT FROM AUTHOR]

Magnetic porous organic polymers (MOPs) with abundant thiol groups were synthesized successfully in high yield through a template-free and catalyst-free diazo-coupling reaction. The reaction was conducted under mild conditions in aqueous solution, in which the introduction of magnetism and thiol-functionalization was realized simultaneously, avoiding the use of environment-unfriendly organic solvents. The magnetic nanoparticles (MNPs) were embedded into hierarchical porous network structures of porous organic polymers (POPs) physically and the magnetism of thiol-functionalized MOPs (MOP-SH) was easily controlled by varying the amount of spiked MNPs. The obtained MOP-SH exhibited high thermal stability and chemical stability within a wide pH range (2-13), and good adsorption performance for Hg(II) over a wide pH range due to the abundant thiols in its hierarchical structure. After the adsorption process by using MOP-SH, the concentration of Hg in the spiked domestic sewage reached 1.1 μg L-1, which is even lower than the acceptable limit of national standard for drinking water (2 μg L-1). Besides, the prepared MOP-SH exhibited high adsorption capacity, fast adsorption kinetics, and easy-recycling behavior, providing a new avenue for the preparation of green functionalized adsorbents with good performance for water decontamination. [ABSTRACT FROM AUTHOR]

ABSTRACT Joint crosslinked gels containing disulfide linkage have been synthesized by oxidation reaction of multi-functional thiol monomers, trimethylolpropane tris(3-mercaptopropionate), tris-[3-mercaptopropionyloxy-ethyl]-isocyanurate, pentaerythritol tetrakis (3-mercaptopropionate), and dipenta-erythritol hexakis (3-mercaptopropionate) in dimethyl sulfoxide (DMSO). Both the oxidation reactions with DMSO at 85 °C and Albright-Goldman oxidation in the presence of acetic anhydride at 50 °C yielded the corresponding gels. The oxidation reaction with DMSO showed higher reaction conversion than that with Albright-Goldman oxidation. Network structure of the gels was quantitatively characterized by means of a scanning microscopic light scattering. The reactions formed homogeneous network structure with about 0.5 nm of mesh in the gels. Mechanical properties of the obtained gels were investigated by compression test. Increasing of the crosslinking density with increasing of the monomer concentration, number of thiol group of the monomer or reaction conversion, raised Young's modulus, and breaking stress of the gels. Cogelation of the tri-, tetra-, of hexa-thiol monomer and dithiol monomers yielded soft and flexible gels. Reduction of the disulfide bonds in the gels by dithiothreitol turned the gel into solution. Heating of the resulting solution induced the regelation by reforming of the disulfide bonds. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 3749-3756 [ABSTRACT FROM AUTHOR]

A method for the quantitation of six polyfunctional thiols, 4-methyl-4-sulfanylpentan-2-one (4MSP), 3-sulfanyl-4-methylpentan-1-ol (3S4MP), 3-sulfanyl-4-methylpentyl acetate (3S4MPA), 3-sulfanyl-3-methylbutan-1-ol (3S3MB), 3-sulfanylhexan-1-ol (3SH), and 3-sulfanylhexyl acetate (3SHA), in hops and beer without organic mercury compounds was developed. The method employed specific extraction of thiols using a silver ion solid phase extraction (SPE) cartridge and gas chromatography--tandem mass spectrometry (GC-MS/MS). For all thiols analyzed, good linearity was achieved by adding thioglycerol as an analyte protectant. Recoveries for both hops (74-100%) and beer (79-113%) were acceptable, and the repeatability for both was also good (relative standard deviations of 2.8-8.4%). The limits of detection for the six polyfunctional thiols were below their odor thresholds in beer. The method was applied to quantitation of hops and beer flavored with thiol-containing hop varieties. Due to their detected levels and level variations in different beers, 4MSP and 3S4MP are thought to be important polyfunctional thiols for the characteristic flavor of hop varieties. [ABSTRACT FROM AUTHOR]

Glycosyl thiols are widely used in stereoselective S-glycoside synthesis. Their epimerization from 1,2-trans to 1,2-cis thiols (e.g., equatorial to axial epimerization in thioglucopyranose) was attained using TiCl4, while SnCl4 promoted their axial-to-equatorial epimerization. The method included application for stereoselective β-D-manno- and β-L-rhamnopyranosyl thiol formation. Complex formation explains the equatorial preference when using SnCl4, whereas TiCl4 can shift the equilibrium toward the 1,2-cis thiol via 1,3-oxathiolane formation. [ABSTRACT FROM AUTHOR]

Objective: Childhood obesity is an important cause of cardiovascular risk with chronic inflammation. Oxidative stress may contribute to the pathogenesis of obesity-related cardiovascular pathologies. We aimed to evaluate thiol/disulphide homeostasis as a novel and sensitive marker of oxidative stress and to evaluate its relationship with some inflammatory and cardiovascular markers in obese children. Methods: In this case-controlled study, 65 children with exogenous obesity and 64 healthy children, as a control group, were included. In both groups, thiol/disulphide homeostasis parameters and inflammatory (white blood cells, platelets, mean corpuscular volume, neutrophil/lymphocyte ratio, and high-sensitivity C-reactive protein) and cardiovascular (epicardial adipose tissue thickness and left ventricular mass index) markers were studied. Correlation analyses of thiol/disulphide homeostasis parameters with body mass index standard deviation scores (BMI SDS) and inflammatory and cardiovascular markers were performed. Receiver-operating characteristic analysis was performed to determine the sensitivity, specificity, and optimal cut-off values of thiol/disulphide homeostasis parameters. Results: Native thiol, total thiol, and native thiol/total thiol ratios (antioxidant parameters) were lower (p<0.05) and disulphide/native thiol and disulphide/total thiol ratios (oxidant parameters) were higher in the obese group than in the control group (p<0.01). A positive correlation of oxidant parameters with BMI SDS and inflammatory markers was found. However, a negative correlation of antioxidant parameters with BMI SDS and inflammatory markers was found. The specificities of disulphide/native thiol and disulphide/total thiol ratios were higher in the obese group. Conclusion: The impairment in thiol/disulphide homeostasis, which is indicative of oxidative stress, is associated with inflammation in obesity. In addition, cardiovascular involvement may also contribute to this impairment. [ABSTRACT FROM AUTHOR]

Poly[2-(methacryloyloxy)ethyl oleate- co-pentafluorophenyl methacrylate] [P(MAEO- co-PFPMA)] random copolymers with oleate and pentafluorophenyl side-chain pendants were synthesized. These copolymers were utilized as dual-reactive polymeric scaffolds in a range of post-polymerization modification strategies involving thiol-ene and para-fluoro-thiol substitution, amidation, trans-esterification, and epoxidation followed by amidation. The 2-(methacryloyloxy)ethyl oleate (MAEO) functional handle in the copolymer is open to functionalization at its internal double bond through thermally initiated thiol-ene reaction, whereas the pentafluorophenyl moiety of the pentafluorophenyl methacrylate (PFPMA) unit undergoes para-fluoro-thiol substitution under basic conditions at room temperature. By means of these modification approaches, the P(MAEO- co-PFPMA) copolymer was orthogonally ligated with thiol compounds having, for example, alkyl, hydroxyl, and protected amine functional groups. Furthermore, different functional groups such as benzyl, allyl, methacrylate, pyrene, and water-soluble poly(ethylene glycol) were easily introduced into the side chain of the P(MAEO- co-PFPMA) copolymer by amidation, trans-esterification, and epoxidation followed by amidation. Functionalization of both the reactive pendants with the various organic substituents was confirmed by 1H and 19F NMR spectroscopy, gel permeation chromatography, and fluorescence spectroscopy. [ABSTRACT FROM AUTHOR]

A copper-catalyzed direct and effective synthesis of aryl thiols from aryl iodides using readily available Na2S·9H2O and 1,2-ethanedithiol was described. A variety of aryl thiols were readily obtained in yields of 76--99%. In this protocol, Na2S·9H2O was used as ultimate sulfur source, and 1,2-ethanedithiol functioned as an indispensable catalytic reagent. [ABSTRACT FROM AUTHOR]

The redox capacity, as well as the aurophilicity of the terminal thiol side groups, in poly(Cysteine) lend a unique characteristic to this poly(amino acid) or polypeptide. There are two major application fields for this polymer: (i) biomedical applications in drug delivery and surface modification of biomedical devices and (ii) as coating for electrodes to enhance their electrochemical sensitivity. The intended application determines the synthetic route for p(Cysteine). Polymers to be used in biomedical applications are typically polymerized from the cysteine N-carboxyanhydride by a ring-opening polymerization, where the thiol group needs to be protected during the polymerization. Advances in this methodology have led to conditions under which the polymerization progresses as living polymerization, which allows for a strict control of the molecular architecture, molecular weight and polydispersity and the formation of block copolymers, which eventually could display polyphilic properties. Poly(Cysteine) used as electrode coating is typically polymerized onto the electrode by cyclic voltammetry, which actually produces a continuous, pinhole-free film on the electrode via the formation of covalent bonds between the amino group of Cysteine and the carbon of the electrode. This resulting coating is chemically very different from the well-defined poly(Cysteine) obtained by ring-opening polymerizations. Based on the structure of cysteine a significant degree of cross-linking within the coating deposited by cyclic voltammetry can be assumed. This manuscript provides a detailed discussion of the ring-opening polymerization of cysteine, a brief consideration of the role of glutathione, a key cysteine-containing tripeptide, and examples for the utilization of poly(Cysteine) and poly(Cysteine)-containing copolymers, in both, the biomedical as well as electrochemical realm. [ABSTRACT FROM AUTHOR]

A highly porous metal–organic frame work Cu3BTC2(copper(II)-benzene-1,3,5-tricarboxylate) that is known as MOF-199 was synthesized from the reaction of 1,3,5-benzenetricarboxylic acid and Cu(OAc)2·H2O by a solvothermal method and characterized by several techniques including FT-IR, XRD, EDX and scanning electron microscopy. The MOF-199 used as an efficient catalyst for one-pot synthesis of thiols by domino reactions of aryl halides and thiourea, and subsequently conversion to aryl alkyl sulfides and diaryl disulfides in polyethylene glycols (PEGs). A variety of aryl alkyl sulfides can be obtained in good to excellent yields in a relatively short reaction time and in the presence of the trace amount of catalyst. Also, the catalyst can be separated from the reaction mixture by decanting, and be reused without significant degradation in catalytic activity. [ABSTRACT FROM PUBLISHER]

Selenomethionine (Sem) has been incorporated recombinantly into proteins many times to elucidate their structure and function. In this paper, we revisit incorporation via chemical protein synthesis to shed light on the mechanism of native chemical ligation. The effect of chalcogen position on ligation is investigated, and selenium-containing peptide ligation is optimized. Additionally, selective methylation is performed on selenolates in a peptide in the presence of unprotected thiols. [ABSTRACT FROM AUTHOR]

Gynecological cancer treatment strategies commonly employ pelvic brachytherapy, a technique that temporarily locates radioactive materials in or near the source of the tumor. Despite numerous advances in brachytherapy treatment protocols, advances in the required vaginal packing materials lag significantly. This paper describes a packing material for vaginal brachytherapy based on a poly(ethylene glycol) (PEG)-based hydrogel. Commercially available oligomeric starting materials rapidly formed a hydrogel upon action of mild base (NaHCO 3 ) through a thiol-Michael addition reaction. Tuning the base concentration enabled rapid formation of hydrogels with moduli sufficient for effective tissue displacement (>10 kPa). The poly(ethylene glycol) diacrylate oligomer molecular weight exerted minimal influence on the hydrogel modulus. The hydrogels absorbed up to four times their weight in water from the dry state. CT imaging demonstrated distinguishability between hydrogel, water, and metal medical tools. The hydrogels did not induce significant IL-8 upregulation or cytotoxicity when cultured against vaginal macrophage cells, suggesting lack of immunogenicity. Our findings support these hydrogels as ideal candidates for a packing material in pelvic brachytherapy applications. [ABSTRACT FROM AUTHOR]

The study reports the synthesis of complexes Co(HL)Cl2 (1), Ni(HL)Cl2 (2), Cu(HL)Cl2 (3), and Zn(HL)3Cl2 (4) with the title ligand, 5-(pyrazin-2-yl)-1,2,4-triazole-5-thione (HL), and their characterization by elemental analyses, ESI-MS (m/z), FT-IR and UV/Vis spectroscopy, as well as EPR in the case of the CuII complex. The comparative analysis of IR spectra of the metal ion complexes with HL and HL alone indicated that the metal ions in 1, 2, and 3 are chelated by two nitrogen atoms, N(4) of pyrazine and N(5) of triazole in the thiol tautomeric form, whereas the ZnII ion in 4 is coordinated by the non-protonated N(2) nitrogen atom of triazole in the thione form. pH potentiometry and UV/Vis spectroscopy were used to examine CoII, NIII, and ZnII complexes in 10/90 (v/v) DMSO/water solution, whereas the CuII complex was examined in 40/60 (v/v) DMSO/water solution. Monodeprotonation of the thione triazole in solution enables the formation of the L:M = 1:1 species with CoII, NIII and ZnII, the 2:1 species with CoII and ZnII, and the 3:1 species with ZnII. A distorted tetrahedral arrangement of the CuII complex was suggested on the basis of EPR and Vis/NIR spectra. [ABSTRACT FROM AUTHOR]

Twelve novel triazolothiadiazole derivatives were synthesized from 4-amino-5-substituted-4H-1,2,4-triazole-3-thiols with various aromatic carboxylic acids by cyclization in the presence of phosphorous oxychloride. All the newly synthesized compounds were characterized by FTIR, ¹H NMR, mass spectroscopy and elemental analysis. The antimicrobial activities of the title compounds were examined by disc diffusion method against Escherichia coli, Staphylococcus aureus, Pyricularia oryzae and Rhizoctnia solani. The bioassay indicated all synthesized triazolothiadiazole derivatives possessed moderate to good antibacterial and antifungal activities against the tested organisms. Especially, compounds 2e and 2k exhibited excellent antibacterial and antifungal activities among these triazolothiadiazole derivatives. [ABSTRACT FROM AUTHOR]

Thiolation of polyaniline (PANI) films with 2-mercaptoethanol was studied by cyclic voltammetry (CV) and chronoamperometry (CA). The sulfur content in the PANI films thiolated in acidic and neutral conditions at different applied potentials was used as the measure of the degree of thiolation. FTIR spectroscopy was used to study the changes in the PANI structure after thiolation. The thiolation experiments were performed in 1.0 M HCl and 0.1 M KCl with three different thiol concentrations. Thiolation provides an easy and straight-forward method to bind covalently molecules, even biomolecules to the PANI backbone. Optimization of the thiolation conditions is the key issue when designing PANI-based biosensors. The results show that with the CA technique it is possible to bind thiolated molecules on PANI both in HCl and in KCl. Furthermore, the results indicate that the potential applied, the thiolation medium and the concentration of the added thiol affect the thiolation process. CA offers an opportunity to enhance the thiolation allowing to some extent also to control the entire process opening up new possibilities to prepare PANI based biosensor substrates. [ABSTRACT FROM AUTHOR]

The removal of heteroelements issued from petroleum products is an important problematic in the developments of the refining processes, in particular for the refining of the unconventional oils for which it is necessary to better understand and quantify the chemical environments of those heteroelements. The aim of this work was to evaluate how the speciation of sulphur, nitrogen and oxygen in oils with the X-ray photoelectron spectroscopy in the “cold” mode could be the appropriate technique. The characterization of liquids and solids with low melting point, has been possible thanks to the use of the liquid nitrogen cooling system, for which the temperature can reach −135 °C on the sample holder in the analysis chamber. The S 2p high resolution spectra recorded for the sulphur organic compounds has allowed establishing a valuable database for sulphur environments where six classes can be distinguished. The methodology developed in this work has been applied to the analysis of a straight run atmospheric residue for which thiol and thiophenic/sulfide environment has been identified. The relative concentration of those two chemical classes has been evaluated. 70% of the whole sulphur is present in thiophenic/sulfide group whereas the rest is thiol chemical class. The analyses performed on hydrotreated effluents highlight larger reactivity of the thiol compounds. But, we are facing a quite high detection limit of the XPS technique estimated at 0.1 at.% not permitting the detection of sulphur in the highly desulphurised effluents. This is still a main limitation for deep hydrotreatment applications but this technique can be used to investigate visbreaking, deasphalting or combustion processes where the heteroelement removing is less severe. Developments on the XPS technique have to be continued in order to reduce its detection limit. The whole quantitative analysis must be considered carefully as hydrogen is not detected by XPS. However, the S/C, N/C and O/C atomic ratio of the reference samples are relatively consistent with combustion techniques. [ABSTRACT FROM AUTHOR]

A series of newer 1,2,4-triazole-3-thiol derivatives 5 ( a – m ) and 6 ( a – i ) containing a triazole fused with pyrazine moiety of pharmacological significance have been synthesized. All the synthesized compounds were screened for their in vitro antileishmanial and antioxidant activities. Compounds 5f (IC 50 = 79.0 µM) and 6f (IC 50 = 79.0 µM) were shown significant antileishmanial activity when compared with standard sodium stibogluconate (IC 50 = 490.0 µM). Compounds 5b (IC 50 = 13.96 µM) and 6b (IC 50 = 13.96 µM) showed significant antioxidant activity. After performing molecular docking study and analyzing overall binding modes it was found that the synthesized compounds had potential to inhibit L. donovani pteridine reductase 1 enzyme. In silico ADME and metabolic site prediction studies were also held out to set an effective lead candidate for the future antileishmanial and antibacterial drug discovery initiatives. [ABSTRACT FROM AUTHOR]

The alkylation of 4,5-dihydro-1 H-imidazole-2-thiol with 1-iodomethyl(dimethyl)phenylsilane, 1-(iodomethyl)-1,1,3,3,3-pentamethyldisiloxane, and 1,3-bis(iodomethyl)-1,1,3,3-tetramethyldisiloxane involved iodine-catalyzed cleavage of the Si-C and Si-O bonds with liberated ( in situ) hydrogen iodide to afford 2-({[(4,5-dihydro-1 H-imidazolium-2-ylsulfanyl)methyl]-1,1,3,3-tetramethyldisiloxanylmethyl}sulfanyl)-4,5-dihydro-1 H-imidazolium di- and tetraiodides. Replacement of iodide ion in the products by triiodide gives new organosilicon ionic liquids with several charged fragments. [ABSTRACT FROM AUTHOR]

A novel thiol-functionalized graphene oxide/Fe-Mn composite (SGO/Fe-Mn) was synthesized via three different methods, i.e., acetic acid method (SGO/Fe-Mn-ac), neutral method (SGO/Fe-Mn-ne), and ammonium hydroxide method (SGO/Fe-Mn-am). The composites were characterized and tested for aqueous methylmercury removal. SGO/Fe-Mn was prepared using 3-mercaptopropyltrimethoxysilane (3-MPTS) as a silanizing reagent, and hydrolyzed 3-MPTS mainly interacted with GO/Fe-Mn through surface oxygen-containing groups (i.e., OH, C O, epoxy C O C, carboxyl O C O, and C O) and π-π interactions, partially through self-polymerization. SGO/Fe-Mn-am showed the largest hydrodynamic diameter, strongest π-π bond, fewest S oxidation products, most thiol groups, negative charge, sp 3 defects, and FeOOH. Pseudo-second-order kinetic model and Langmuir and Freundlich isotherm models fitted well with methylmercury sorption kinetic and isotherm data, respectively, resulting in a CH 3 Hg + maximum sorption capacity of 43.88 mg/g for SGO/Fe-Mn-am, 36.33 mg/g for SGO/Fe-Mn-ac, and 28.00 mg/g for SGO/Fe-Mn-ne. The removal mechanism was described by electrostatic attraction, ligand exchange, and surface complexation. This study demonstrates potential and viability of SGO/Fe-Mn for enhanced immobilization of CH 3 Hg + in surface water, groundwater, and soil/sediments. [ABSTRACT FROM AUTHOR]

Cysteine (Cys), homocysteine (Hcy) and Glutathione (GSH) are small-molecular biothiols that play key roles in various biological systems. The development of fluorescent probes for thiols has attracted intense interest. Inspired by the appealing advantages of near-infrared (NIR) fluorescent detection, we herein report a novel NIR fluorescent probe for biothiols detection based on the widely-used thiol-selective 2,4-dinitro-benzenesulfonyl (DNBS) group. The probe is intrinsically nonfluorescent; however, after being reacted with thiols, the DNBS group is substituted by the −SH group, which elicits a significant NIR fluorescent turn-on response. Probe displays 160-fold fluorescence intensity enhancement at 688 nm with 2 equiv of Cys in neutral buffer. More importantly, the probe features a good linearity range and the detection limit is as low as 63 nM. In addition, the probe uses long wavelength excitation (620 nm), all of such good properties proving it to be a good sensor for the selective detection of thiols and a potential use in biological applications. [ABSTRACT FROM AUTHOR]

A rapid and facile method provides a general route to sulfonyl bromides/chlorides by the oxidation of thiols using NXS – ROH (X = Br,Cl, R = i Pr) as an oxyhalogenation reagent. Control experiments suggest that the alcohol component is the source of oxygen. The proposed method enable the access to structurally diverse sulfonyl bromides and chlorides including challenging examples, inaccessible by other synthetic methods. [ABSTRACT FROM AUTHOR]

An efficient and environment-friendly procedure for the synthesis of a new series of nitrogen bridge-head [1,2,4]triazolo[5,1-c][1,2,4]triazepine derivatives through one-pot three-component reaction of polyfunctional triazole with aromatic aldehydes and acetophenone derivatives using alcoholic sodium hydroxide solution. The same new products were prepared in classical route through reaction of triazole with the corresponding chalcones under the same conditions. [ABSTRACT FROM PUBLISHER]

Two types of fibrous adsorbents, thiol- and amino- functionalized polysilsesquioxane coated poly( p -phenylenetherephthal amide) (PPTA) fibers (PPTA-PAPSQ and PPTA-PMPSQ), were prepared via the in situ condensations with aminopropyltriethoxysilane (APTES) and mercaptopropyltriethoxysilane (MPTES) on the surface of PPTA fibers, respectively. Their structures were characterized by FTIR, FE-SEM, XPS, XRD, TG, Elemental analysis, and pore structure analysis. The effect of the ratio of reactants on the structures of these two modified fibers was investigated. The results of nitrogen adsorption-desorption isotherms revealed that the polysilsesquioxane coating on the surface of PPTA-PMPSQ samples exhibited open meso- or macroporous features, while those on the surface of PPTA-PAPSQ samples formed dense gel structures. Moreover, Hg (II) was chosen as a representative to evaluate the adsorption properties of PPTA-PAPSQ and PPTA-PMPSQ samples. The results showed that the adsorption processes of Hg(II) followed well pseudo-second-order model onto the two series adsorbents. The Langmuir was the better-fit model to predict the experimental data. The theoretical saturation adsorption capacities of polysilsesquioxanes coated on the PPTA-PAPSQ and PPTA-PMPSQ adsorbents can reach 3.52–10.64 mmol g −1 and 7.43–10.22, mmol g −1 , respectively. The result showed that PPTA-PAPSQ and PPTA-PMPSQ adsorbents can selectively adsorb Hg(II) from binary component metal ion systems. [ABSTRACT FROM AUTHOR]

Tuberculosis is a worldwide disease considered as a major health problem with high morbidity and mortality rates. Poor detection of Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis remains a major obstacle to the global control of this disease. Here we report the development of a new test based on the detection of the major virulent factor of Mtb, namely the early secreted antigenic target 6-kDa protein or ESAT-6. A label free electrochemical immunosensor using an anti-ESAT-6 monoclonal antibody as a bio-receptor is described herein. Anti-ESAT-6 antibodies were first covalently immobilized on the surface of a gold screen-printed electrode functionalized via a self-assembled thiol monolayer. Interaction between the bio-receptor and ESAT-6 antigen was evaluated by square wave voltammetry method using [F e (CN) 6 ] 3 −/4 − as redox probe. The detection limit of ESAT-6 antigen was 7 ng/ml. The immunosensor has also been able to detect native ESAT-6 antigen secreted in cell culture filtrates of three pathogenic strains of Mtb (CDC1551, H37RV and H8N8). Overall, this work describes an immune-electrochemical biosensor, based on ESAT-6 antigen detection, as a useful diagnostic tool for tuberculosis. [ABSTRACT FROM AUTHOR]

Fully spin delocalized mixed valence copper–sulfur clusters, 1 and 2, supported by μ4-sulfido and NSthiol donor ligands are synthesized and characterized. Wheel shaped 1 consists of Cu2S2 units. The unprecedented nanoball 2 can be described as S@Cu4(tetrahedron)@O6(octahedron)@Cu12S12(cage) consisting of both Cu2S2 and (μ4-S)Cu4 units. The Cu2S2 and (μ4-S)Cu4 units resemble biological CuA and CuZ sites respectively. [ABSTRACT FROM AUTHOR]

The unique biophysical and electronic properties of cysteine make this molecule one of the most biologically critical amino acids in the proteome. The defining sulfur atom in cysteine is much larger than the oxygen and nitrogen atoms more commonly found in the other amino acids. As a result of its size, the valence electrons of sulfur are highly polarizable. Unique protein microenvironments favor the polarization of sulfur, thus increasing the overt reactivity of cysteine. Here, we provide a brief overview of the endogenous generation of reactive oxygen and electrophilic species and specific examples of enzymes and transcription factors in which the oxidation or covalent modification of cysteine in those proteins modulates their function. The perspective concludes with a discussion of cysteine chemistry and biophysics, the hard and soft acids and bases model, and the proposal of the Soft Cysteine Signaling Network: a hypothesis proposing the existence of a complex signaling network governed by layered chemical reactivity and cross-talk in which the chemical modification of reactive cysteine in biological networks triggers the reorganization of intracellular biochemistry to mitigate spikes in endogenous or exogenous oxidative or electrophilic stress. [ABSTRACT FROM AUTHOR]