Showing papers on "Thiocyanate published in 2014"

EXAFS study into the speciation of metal salts dissolved in ionic liquids and deep eutectic solvents.

Abstract: The speciation of metals in solution controls their reactivity, and this is extremely pertinent in the area of metal salts dissolved in ionic liquids. In the current study, the speciation of 25 metal salts is investigated in four deep eutectic solvents (DESs) and five imidazolium-based ionic liquids using extended X-ray absorption fine structure. It is shown that in diol-based DESs MI ions form [MCl2]− and [MCl3]2– complexes, while all MII ions form [MCl4]2– complexes, with the exception of NiII, which exhibits a very unusual coordination by glycol molecules. This was also found in the X-ray crystal structure of the compound [Ni(phen)2(eg)]Cl2·2eg (eg = ethylene glycol). In a urea-based DES, either pure chloro or chloro–oxo coordination is observed. In [C6mim][Cl] pure chloro complexation is also observed, but coordination numbers are smaller (typically 3), which can be explained by the long alkyl chain of the cation. In [C2mim][SCN] metal ions are entirely coordinated by thiocyanate, either through the N...

Oxygen-atom transfer reactivity of axially ligated Mn(V)−oxo complexes: Evidence for enhanced electrophilic and nucleophilic pathways

Abstract: Addition of anionic donors to the manganese(V)–oxo corrolazine complex MnV(O)(TBP8Cz) has a dramatic influence on oxygen-atom transfer (OAT) reactivity with thioether substrates. The six-coordinate anionic [MnV(O)(TBP8Cz)(X)]− complexes (X = F–, N3–, OCN–) exhibit a ∼5 cm–1 downshift of the Mn–O vibrational mode relative to the parent MnV(O)(TBP8Cz) complex as seen by resonance Raman spectroscopy. Product analysis shows that the oxidation of thioether substrates gives sulfoxide product, consistent with single OAT. A wide range of OAT reactivity is seen for the different axial ligands, with the following trend determined from a comparison of their second-order rate constants for sulfoxidation: five-coordinate ≈ thiocyanate ≈ nitrate < cyanate < azide < fluoride ≪ cyanide. This trend correlates with DFT calculations on the binding of the axial donors to the parent MnV(O)(TBP8Cz) complex. A Hammett study was performed with p-X-C6H4SCH3 derivatives and [MnV(O)(TBP8Cz)(X)]− (X = CN– or F–) as the oxidant, and ...

The influence of H-bonding on the ‘ambidentate’ coordination behaviour of the thiocyanate ion to Cd(II): a combined experimental and theoretical study

Abstract: Two new trinuclear hetero-metallic copper(II)–cadmium(II) complexes [(CuL)2Cd(NCS)2] (1) and [(CuLR)2Cd(SCN)2] (2) have been synthesized using [CuL] and [CuLR] as “metalloligands” (where H2L = N,N′-bis(salicylidene)-1,4-butanediamine and H2LR = N,N′-bis(2-hydroxybenzyl)-1,4-butanediamine) respectively. Both the complexes were characterized by elemental analysis, various spectroscopic methods and single crystal XRD. Complex 1 is an angular trinuclear species, in which two terminal four-coordinate square planar “metalloligands” [CuL] are coordinated to a central Cd(II) through double phenoxido bridges along with two mutually cis nitrogen atoms of terminal thiocyanate ions. In complex 2, which is linear, in addition to the double phenoxido bridge, two SCN− coordinate to the trans positions of the central octahedral Cd(II) via S atoms. Theoretical calculations on the energetic difference between the two possible coordination modes of the thiocyanate anion to the Cd atom reveal that N-coordination is preferred over S-coordination in agreement with the much greater abundance of the reported N-bonded structures. In 2, there is a strong N–H⋯NCS–Cd H-bonding interaction, the binding energy of which is computed to be approximately −9.3 kcal mol−1, which is sufficient to compensate the 9.0 kcal mol−1 of energetic cost due to the unusual Cd–SCN coordination mode.

Colorimetric sensor for thiocyanate based on anti-aggregation of citrate-capped gold nanoparticles

Abstract: A convenient colorimetric sensor based on anti-aggregation of citrate-capped gold nanoparticles (AuNPs) is demonstrated for thiocyanate (SCN − ) sensing. The citrate-capped AuNPs aggregated readily in the presence of sulfuric acid, leading to a color change from red to blue. This particle aggregation could be suppressed by SCN − , which had strong protective effect on the gold colloid. The thiocyanate recognition suffers insignificant interference from most of common ions. With this strategy, 1 μM of SCN − can be recognized within 5 min by naked-eye observation. This simple, selective, and sensitive approach can be potentially applied for SCN − assays in environmental aqueous samples.

Synthesis, Characterization, and Thermophysical Properties of 1,8-Diazobicyclo[5.4.0]undec-7-ene Based Thiocyanate Ionic Liquids

Abstract: In this work, synthesis of 12 ionic liquids based on 1,8-diazobicyclo[5.4.0]undec-7-ene (DBU) cation with anions such as chloride, bromide, and thiocyanate were performed. The new ionic liquids were characterized using nuclear magnetic resonance spectroscopy and elemental analysis. The effect of alkyl spacer length on the physicochemical properties of DBU based ionic liquids was studied by attaching ethyl, butyl, hexyl, octyl, decyl, and tetradecyl groups to the DBU cation. The effects of temperature on the density and viscosity over a temperature range from 293.15 K to 373.15 K were recorded at atmospheric pressure. From the experimental density values, the thermal expansion coefficient values were calculated. The surface tension of the neat ionic liquids was measured at seven different temperatures (293.15 K, 303.15 K, 313.15 K, 323.15 K, 333.15 K, 343.15 K, and 353.15 K). The surface entropy and surface enthalpy were calculated from the experimental surface tension value at 303.15 K. The thermal behavi...

Air-stable, nanostructured electronic and plasmonic materials from solution-processable, silver nanocrystal building blocks.

Abstract: Herein we describe a room-temperature, chemical process to transform silver nanocrystal solids, deposited from colloidal solutions, into highly conductive, corrosion-resistant, optical and electronic materials with nanometer-scale architectures. After assembling the nanocrystal solids, we treated them with a set of simple, compact, organic and inorganic reagents: ammonium thiocyanate, ammonium chloride, potassium hydrogen sulfide, and ethanedithiol. We find that each reagent induces unique changes in the structure and composition of the resulting solid, giving rise to films that vary from insulating to, in the case of thiocyanate, conducting with a remarkably low resistivity of 8.8 × 10–6 Ω·cm, only 6 times that of bulk silver. We show that thiocyanate mediates the spontaneous sintering of nanocrystals into structures with a roughness of less than 1/10th of the wavelength of visible light. We demonstrate that these solution-processed, low-resistivity, optically smooth films can be patterned, using imprint...

Isolation of Two Different Ni2Zn Complexes with an Unprecedented Cocrystal Formed by One of Them and a “Coordination Positional Isomer” of the Other

Abstract: A new homometallic trinuclear Ni(II) complex [(NiL)2Ni(NCS)2] (1) and three heterometallic trinuclear Ni(II)–Zn(II)–Ni(II) complexes [(NiL)2Zn(NCS)2] (2), [(NiL)2Zn(NCS)2(CH3OH)2]·2CH3OH (3) and {[(NiL)2Zn(NCS)2(CH3OH)2]} {[(NiL)2Zn(NCS)2]} (4) have been synthesized by using the “complex as ligand” approach with the “metalloligand” [NiL] (H2L = N,N′-bis(salicylidene)-1,3-propanediamine) and thiocyanate in different ratios. All the complexes have been structurally and magnetically characterized. In the isomorphous complexes 1 and 2, the two terminal square planar Ni atoms and the central octahedral nickel atom (in 1) or zinc atom (in 2) are arranged in a bent structure where two cis κN-SCN– thiocyanate ions are coordinated to the central atom. The chemical composition of 3 is very similar to that of 2 but, in 3, the central Zn atom is tetrahedral and the κN-SCN– thiocyanate ions occupy an axial position of each terminal nickel atom (which now are octahedral with the sixth position occupied by a methanol mo...

Cyanide Toxicokinetics: The Behavior of Cyanide, Thiocyanate and 2-Amino-2-Thiazoline-4-Carboxylic Acid in Multiple Animal Models

Abstract: Cyanide causes toxic effects by inhibiting cytochrome c oxidase, resulting in cellular hypoxia and cytotoxic anoxia, and can eventually lead to death. Cyanide exposure can be verified by direct analysis of cyanide concentrations or analyzing its metabolites, including thiocyanate (SCN(-)) and 2-amino-2-thiazoline-4-carboxylic acid (ATCA) in blood. To determine the behavior of these markers following cyanide exposure, a toxicokinetics study was performed in three animal models: (i) rats (250-300 g), (ii) rabbits (3.5-4.2 kg) and (iii) swine (47-54 kg). Cyanide reached a maximum in blood and declined rapidly in each animal model as it was absorbed, distributed, metabolized and eliminated. Thiocyanate concentrations rose more slowly as cyanide was enzymatically converted to SCN(-). Concentrations of ATCA did not rise significantly above the baseline in the rat model, but rose quickly in rabbits (up to a 40-fold increase) and swine (up to a 3-fold increase) and then fell rapidly, generally following the relative behavior of cyanide. Rats were administered cyanide subcutaneously and the apparent half-life (t1/2) was determined to be 1,510 min. Rabbits were administered cyanide intravenously and the t1/2 was determined to be 177 min. Swine were administered cyanide intravenously and the t1/2 was determined to be 26.9 min. The SCN(-) t1/2 in rats was 3,010 min, but was not calculated in rabbits and swine because SCN(-) concentrations did not reach a maximum. The t1/2 of ATCA was 40.7 and 13.9 min in rabbits and swine, respectively, while it could not be determined in rats with confidence. The current study suggests that cyanide exposure may be verified shortly after exposure by determining significantly elevated cyanide and SCN(-) in each animal model and ATCA may be used when the ATCA detoxification pathway is significant.

Extractive Desulfurization of Liquid Fuels by Energy Efficient Green Thiazolium based Ionic Liquids

Abstract: In the present paper, experimental data on extractive desulfurization of liquid fuel using 3-butyl-4-methylthiazolium thiocyanate [BMTH]SCN is presented. The Fourier transform infrared (FTIR), 1H NMR, and 13C NMR analyses have been discussed for the molecular confirmation of synthesized [BMTH]SCN. Further, conductivity, solubility, and viscosity analyses of [BMTH]SCN were performed. The effects of reaction time, reaction temperature, sulfur compounds, ultrasonication, and recycling of [BMTH]SCN without regeneration on removal of dibenzothiophene from liquid fuel were also investigated. In the extractive desulfurization process, the removal of dibenzothiophene in octane was 81.2% for mass ratio of 1:1 in 30 min at 30 °C under the mild reaction conditions. Thiazolium ionic liquids could be reused five times without a significant decrease in activity. Also, the desulfurization of real fuels, multistage extraction was examined. The data and results provided in present paper explore the significant insights of...

Microwave-assisted synthesis of asymmetric disulfides

Abstract: Thiourea is very useful in the synthesis of asymmetric and symmetric disulfides. In this paper, we report an efficient, odorless, and one-pot procedure for the synthesis of benzyl alkyl disulfides by using the mixtures of thiourea, alkyl halides, and benzyl thiocyanates. The reaction was carried out in water with the assistance of microwaves, enabling a time-saving process. Optimal conditions were obtained as follows: benzyl thiocyanate (1.0 equiv.), thiourea (2.0 equiv.), and alkyl halide (1.2 equiv.) were reacted under microwave irradiation using K3PO4 as the base in water at 90 °C for 15 min. In most cases, the yields are higher than 80%. In this protocol, the substrates are readily available and their synthesis is much easier than the corresponding thiols. Moreover, it is environmentally and economically friendly.

The association between perchlorate and thiocyanate exposure and thyroid function in first-trimester pregnant Thai women.

Abstract: Context: Thyroid hormone is critical for fetal neurodevelopment. Perchlorate and thiocyanate decrease thyroidal iodine uptake by competitively inhibiting the sodium/iodide symporter. It is clear that perchlorate and thiocyanate anions can influence thyroid function. However, as pollutants in the environment, their impact is conflicting. Objective: The objective was to determine the effects of environmental perchlorate and/or thiocyanate exposure on thyroid function in first-trimester pregnant women. Design and Patients: A cross-sectional study was conducted in 200 pregnant Thai women with a gestational age of 14 weeks or less. Measures: Urinary iodide, perchlorate, thiocyanate, and serum thyroid function tests were measured. Results: The women were aged 28.6 ± 6.1 years and the mean gestational age was 9.6 ± 2.7 weeks. Median urinary iodide, perchlorate, and thiocyanate concentrations were 153.5 μg/L, 1.9 μg/L, and 510.5 μg/L, respectively. Using Spearman's rank correlation analyses, there were positive c...

Conversion of high-spin iron(III)–alkylperoxo to iron(IV)–oxo species via O–O bond homolysis in nonheme iron models

Abstract: The mechanism of the alkylperoxo O–O bond cleavage of low-spin iron(III)–alkylperoxo species has been well established in nonheme iron models. In contrast, the alkylperoxo O–O bond cleavage in nonheme high-spin iron(III)–alkylperoxo species binding an axial ligand has yet to be elucidated. Herein, we report the synthesis and characterization of mononuclear nonheme high-spin iron(III)–alkylperoxo complexes each bearing an N-tetramethylated 13-membered macrocyclic ligand (13-TMC), [FeIII(OOC(CH3)3)(13-TMC)]2+ and [FeIII(OOC(CH3)2C6H5)(13-TMC)]2+. The high-spin iron(III)–alkylperoxo complexes were converted to an iron(IV)–oxo complex at a fast rate upon addition of thiocyanate (NCS−) via the formation of a short-lived intermediate. This intermediate was identified as a high-spin iron(III)–alkylperoxo complex binding a thiocyanate ion as an axial ligand by characterizing it with various spectroscopic methods and density functional theory (DFT) calculations. We have also provided strong evidence that conversion of the high-spin iron(III)–alkylperoxo complex to its corresponding iron(IV)–oxo complex occurs via O–O bond homolysis. Thus, we have concluded that the role of the axial ligand binding to a high-spin iron(III)–alkylperoxo complex is to facilitate the alkylperoxo O–O bond cleavage via the “push effect”, which has been well established in heme enzymes. To the best of our knowledge, the present study reports the first clear example showing the O–O bond homolysis of a high-spin iron(III)–alkylperoxo complex and the axial ligand effect on the alkylperoxo O–O bond cleavage in nonheme iron models.

Nitrile-substituted silanes and electrolyte compositions and electrochemical devices containing them

Abstract: Described herein are liquid, organosilicon compounds that including a substituent that is a cyano (—CN), cyanate (—OCN), isocyanate (—NCO), thiocyanate (—SCN) or isothiocyanate (—NCS). The organosilicon compounds are useful in electrolyte compositions and can be used in any electrochemical device where electrolytes are conventionally used.

Highly sensitive and selective determination of thiocyanate using gold nanoparticles surface decorated multi-walled carbon nanotubes modified carbon paste electrode

Abstract: Gold nanoparticles and multi-walled carbon nanotubes were used to fabricate a modified electrode, as a highly sensitive and selective voltammetric sensor, for the determination of thiocyanate A fast and easy method for the fabrication of gold nanoparticles/multi walled carbon nanotube/carbon paste electrode (GNPs/MWCPE) by cyclic voltammetry was used Scanning electron microscopy (SEM) image demonstrated that the gold nanoparticles deposited on MWCNTs/CPE, with an average size of 30 nm By combining the benefits of GNPs/MWCNTs and CPE, the resulted modified electrode exhibited outstanding electrocatalytic activity in terms of thiocyanate oxidation by giving much higher peak currents than those obtained for the unmodified CPE and also the MWCNTs-modified electrode The effects of various experimental parameters on the voltammetric response of thiocyanate were investigated At the optimum conditions the sensor has a linear response in the 001–2000 μmol L−1 concentration range, a very good detection sensitivity (29046 μA L μmol−1), and a low detection limit of 5 × 10−3 μmol L−1 of thiocyanate The proposed electrode was used to the determination of SCN– in saliva, urine and water samples and the results were found to be in good agreement with the values obtained by standard method

Simultaneous high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS-MS) analysis of cyanide and thiocyanate from swine plasma

Abstract: An analytical procedure for the simultaneous determination of cyanide and thiocyanate in swine plasma was developed and validated. Cyanide and thiocyanate were simultaneously analyzed by high-performance liquid chromatography tandem mass spectrometry in negative ionization mode after rapid and simple sample preparation. Isotopically labeled internal standards, Na13C15N and NaS13C15N, were mixed with swine plasma (spiked and nonspiked), proteins were precipitated with acetone, the samples were centrifuged, and the supernatant was removed and dried. The dried samples were reconstituted in 10 mM ammonium formate. Cyanide was reacted with naphthalene-2,3-dicarboxaldehyde and taurine to form N-substituted 1-cyano[f]benzoisoindole, while thiocyanate was chemically modified with monobromobimane to form an SCN-bimane product. The method produced dynamic ranges of 0.1–50 and 0.2–50 μM for cyanide and thiocyanate, respectively, with limits of detection of 10 nM for cyanide and 50 nM for thiocyanate. For quality control standards, the precision, as measured by percent relative standard deviation, was below 8 %, and the accuracy was within ±10 % of the nominal concentration. Following validation, the analytical procedure successfully detected cyanide and thiocyanate simultaneously from the plasma of cyanide-exposed swine.

Isolation and characterization of an obligately chemolithoautotrophic Halothiobacillus strain capable of growth on thiocyanate as an energy source

Abstract: Molecular and microbiological analysis of a laboratory bioreactor biomass oxidizing thiocyanate at autotrophic conditions and at 1 M NaCl showed a domination of a single chemolithoautotrophic sulfur-oxidizing bacterium (SOB) capable of using thiocyanate as an energy source The bacterium was isolated in pure cultures and identified as a member of the Halothiobacillus halophilus/hydrothermalis clade This clade includes moderately halophilic chemolithoautotrophic SOB from marine and hypersaline habitats for which the ability to utilize thiocyanate as an electron donor has not been previously demonstrated Halothiobacillus sp strain SCN-R1 grew with thiocyanate as the sole energy and nitrogen source oxidizing it to sulfate and ammonium via the cyanate pathway The pH range for thiocyanate oxidation was within a neutral region between 7 and 8 and the range of salinity was from 02 to 15 M NaCl, with an optimum at 05 M Despite the close phylogenetic relatedness, none of the tested type strains and other isolates from the H halophilus/hydrothermalis group exhibited thiocyanate-oxidizing capacity

Thiocyanate complexes of uranium in multiple oxidation states: a combined structural, magnetic, spectroscopic, spectroelectrochemical, and theoretical study.

Abstract: A comprehensive study of the complexes A4[U(NCS)8] (A = Cs, Et4N, nBu4N) and A3[UO2(NCS)5] (A = Cs, Et4N) is described, with the crystal structures of [nBu4N]4[U(NCS)8]·2MeCN and Cs3[UO2(NCS)5]·O0.5 reported. The magnetic properties of square antiprismatic Cs4[U(NCS)8] and cubic [Et4N]4[U(NCS)8] have been probed by SQUID magnetometry. The geometry has an important impact on the low-temperature magnetic moments: at 2 K, μeff = 1.21 μB and 0.53 μB, respectively. Electronic absorption and photoluminescence spectra of the uranium(IV) compounds have been measured. The redox chemistry of [Et4N]4[U(NCS)8] has been explored using IR and UV–vis spectroelectrochemical methods. Reversible 1-electron oxidation of one of the coordinated thiocyanate ligands occurs at +0.22 V vs Fc/Fc+, followed by an irreversible oxidation to form dithiocyanogen (NCS)2 which upon back reduction regenerates thiocyanate anions coordinating to UO22+. NBO calculations agree with the experimental spectra, suggesting that the initial electro...

Occurrence of Perchlorate and Thiocyanate in Human Serum From E-Waste Recycling and Reference Sites in Vietnam: Association With Thyroid Hormone and Iodide Levels

Abstract: Perchlorate (ClO4 −) and thiocyanate (SCN−) interfere with iodide (I−) uptake by the sodium/iodide symporter, and thereby these anions may affect the production of thyroid hormones (THs) in the thyroid gland. Although human exposure to perchlorate and thiocyanate has been studied in the United States and Europe, few investigations have been performed in Asian countries. In this study, we determined concentrations of perchlorate, thiocyanate, and iodide in 131 serum samples collected from 2 locations in Northern Vietnam, Bui Dau (BD; electrical and electronic waste [e−waste] recycling site) and Doung Quang (DQ; rural site) and examined the association between serum levels of these anions with levels of THs. The median concentrations of perchlorate, thiocyanate, and iodide detected in the serum of Vietnamese subjects were 0.104, 2020, and 3.11 ng mL−1, respectively. Perchlorate levels were significantly greater in serum of the BD population (median 0.116 ng mL−1) than those in the DQ population (median 0.086 ng mL−1), which indicated greater exposure from e-waste recycling operations by the former. Serum concentrations of thiocyanate were not significantly different between the BD and DQ populations, but increased levels of this anion were observed among smokers. Iodide was a significant positive predictor of serum levels of FT3 and TT3 and a significant negative predictor of thyroid-stimulating hormone in males. When the association between serum levels of perchlorate or thiocyanate and THs was assessed using a stepwise multiple linear regression model, no significant correlations were found. In addition to greater concentrations of perchlorate detected in the e-waste recycling population, however, given that lower concentrations of iodide were observed in the serum of Vietnamese females, detailed risk assessments on TH homeostasis for females inhabiting e-waste recycling sites, especially for pregnant women and their neonates, are required.