Showing papers on "Thiocyanate published in 2000"
TL;DR: It is concluded that not only plasma and salivary thiocyanate levels but also blood cyanide level can be suitable indices for distinguishing smokers from nonsmokers.
Abstract: Cyanide and thiocyanate levels were determined by head space gas chromatography and the spectrophotometric Konig method respectively, for blood and salivary samples collected from 40 healthy adult volunteers. Blood cyanide (mean±standard deviation : 0.27±0.07μм), plasma thiocyanate (111.2±92.1μм), salivary cyanide (0.66±0.52μм) and salivary thiocyanate (1655±841μм) levels were significantly higher in the group of 20 tobacco smokers than in the group of 20 nonsmokers (0.17±0.04μм, 33.5±25.4μм, 0.38±0.26μм, 542±406μм). Statistical correlations were observed between the blood cyanide and the salivary thiocyanate levels (γ=0.64), between the blood cyanide and the plasma thiocyanate levels (γ=0.54), and between the plasma thiocyanate and the salivary thiocyanate levels (γ=0.46). It is concluded that not only plasma and salivary thiocyanate levels but also blood cyanide level can be suitable indices for distinguishing smokers from nonsmokers.
151 citations
TL;DR: In this paper, zinc and cadmium solvent extraction from cobalt and nickel was studied using 30% Aliquat 336 in either the chloride (R4NCl) or thiocyanate (R 4NSCN) forms, and in a mixed aromatic-aliphatic diluent.
122 citations
TL;DR: In this paper, transient kinetic measurements of the formation of compound I of human eosinophil peroxidase (EPO) and its reaction with halides and thiocyanate, using the sequential-mixing stopped-flow technique, were presented.
Abstract: Compound I of peroxidases takes part in both the peroxidation and the halogenation reaction. This study for the first time presents transient kinetic measurements of the formation of compound I of human eosinophil peroxidase (EPO) and its reaction with halides and thiocyanate, using the sequential-mixing stopped-flow technique. Addition of 1 equiv of hydrogen peroxide to native EPO leads to complete formation of compound I. At pH 7 and 15 °C, the apparent second-order rate constant is (4.3 ± 0.4) × 107 M-1 s-1. The rate for compound I formation by hypochlorous acid is (5.6 ± 0.7) × 107 M-1 s-1. EPO compound I is unstable and decays to a stable intermediate with a compound II-like spectrum. At pH 7, the two-electron reduction of compound I to the native enzyme by thiocyanate has a second-order rate constant of (1.0 ± 0.5) × 108 M-1 s-1. Iodide [(9.3 ± 0.7) × 107 M-1 s-1] is shown to be a better electron donor than bromide [(1.9 ± 0.1) × 107 M-1 s-1], whereas chloride oxidation by EPO compound I is extremel...
102 citations
TL;DR: Adding iodide with thiocyanate increased the fungicidal and bactericidal effect against Candida albicans, Escherichia coli and Staphylococcus aureus and Pseudomonas aeruginosa and showed the same inhibition in the LP system with iodide and without iodide.
Abstract: The lactoperoxidase (LP) system is a natural antimicrobial system, the use of which has been suggested as a preservative in foods and pharmaceuticals. The effect of adding iodide to the LP system, the chemical stability and the change in antimicrobial effectiveness during storage was studied. Addition of iodide with thiocyanate increased the fungicidal and bactericidal effect against Candida albicans, Escherichia coli and Staphylococcus aureus. Pseudomonas aeruginosa showed the same inhibition in the LP system with iodide and without iodide. Storage of the LP system in completely filled airtight containers for 18 months caused a 35% loss of the initial thiocyanate concentration. The antimicrobial activity of this LP system was strong enough to kill inocula of 10(6) cfu ml(-1) of the four test organisms within 2 h of contact time. During storage of the air-containing LP system, the concentration of thiocyanate was reduced below detection limit within 7 d, the concentrations of hypothiocyanite and hypoiodite within 350 d. After 516 d the antimicrobial activity of air-containing LP system was strong enough to kill inocula of 10(6) cfu ml(-1) Ps. aeruginosa within 2 h, Staph. aureus within 4 h and Candida albicans and E. coli within 1 week of contact time.
101 citations
TL;DR: A tridentate Schiff base ligand (LH) has been synthesized from 2-hydroxyacetophenone and 2-dimethylaminoethylamine as discussed by the authors, which forms the neutral complexes [Co(L)(N3){o-(CH3CO)C6H4O}] (1) and [Co[L)(SCN]·1/2H2O (2) in presence of equivalent amount of Co(II) acetate, and sodium azide for 1 and sodium thiocyanate for 2).
90 citations
TL;DR: In this paper, the FTIR spectra of lithium perchlorate and lithium thiocyanate in acetonitrile, benzonitrile and propylene carbonate were recorded in the temperature range from 5to 45°C.
Abstract: FTIR spectra of lithium perchlorate and lithium thiocyanate in acetonitrile,benzonitrile, and propylene carbonate were recorded in the temperature range from 5to 45°C. New bands due to solvent molecules in the primary solvation shell ofthe lithium ions were detected in the region of the CN stretching mode of thenitriles and of the CO stretching mode of propylene carbonate. The band structureswere studied in detail by deconvolution with band-fitting procedures and meancation solvation numbers were deduced from the band area of the bulk solvent.For the systems acetonitrile—lithium perchlorate, benzonitrile—lithiumperchlorate, and benzonitrile—lithium thiocyanate, solvation numbers of “free” and“bound” lithium ions were calculated with the help of the degree of associationobtained from suitable anion vibrations.
89 citations
TL;DR: The designed drugs possessing the 4-phenoxyphenoxy skeleton and other closely related structures employing the thiocyanate moiety as polar end group were designed, synthesized, and evaluated as antiproliferative agents against Trypanosoma cruzi, the parasite responsible for this disease.
Abstract: As a part of our project directed at the search of new chemotherapeutic agents against American trypanosomiasis (Chagas' disease), several drugs possessing the 4-phenoxyphenoxy skeleton and other closely related structures employing the thiocyanate moiety as polar end group were designed, synthesized, and evaluated as antiproliferative agents against Trypanosoma cruzi, the parasite responsible for this disease. These thiocyanate analogues were envisioned bearing in mind the potent activity shown by 4-phenoxyphenoxyethyl thiocyanate (compound 8) taken as lead drug. This compound had previously proved to be an extremely active growth inhibitor against T. cruzi with IC(50) values ranging from the very low micromolar level in epimastigotes to the low nanomolar level in the intracellular form of the parasite. Of the designed compounds, the ethyl thiocyanate drugs connected to nonpolar skeletons, namely, arylthio, 2,4-dichlorophenoxy, ortho-substituted aryloxy, and 2-methyl-4-phenoxyphenoxy (compounds 15, 34, 47, 52, 72, respectively), were shown to be very potent antireplicative agents against T. cruzi. On the other hand, conformationally restricted analogues as well as branched derivatives at the aliphatic side chain were shown to be moderately active against T. cruzi growth. The biological activity of drugs bearing the thiocyanate group correlated quite well with the activity exhibited by their normal precursors, the tetrahydropyranyl ether derivatives, when bonded to the same nonpolar skeleton. Compounds having the tetrahydropyranyl moeity as polar end were proportionally much less active than sulfur-containing derivatives in all cases. Drugs 47 and 72 also resulted to be very active against the amastigote form of the parasite growing in myoblasts; however, they were slightly less active than the lead drug 8. On the other hand, compounds 34 and 52 were almost devoid of activity against myoblasts. Surprisingly, the dithio derivative 15 was toxic for myoblasts.
70 citations
TL;DR: CO dehydrogenase is a selenium-containing molybdo-iron-sulfur-flavoenzyme, which has been crystallized and structurally characterized in its oxidized state from the aerobic CO utilizing bacteria Oligotropha carboxidovorans and Hydrogenophaga pseudoflava.
Abstract: CO dehydrogenase (EC 1.2.99.2) catalyzes the oxidation of CO according to the following equation: CO + H2O-->CO2 + 2 e- + 2 H+. It is a selenium-containing molybdo-iron-sulfur-flavoenzyme, which has been crystallized and structurally characterized in its oxidized state from the aerobic CO utilizing bacteria Oligotropha carboxidovorans and Hydrogenophaga pseudoflava. Both CO dehydrogenase structures show only minor differences, and the enzymes are dimers of two heterotrimers. Each heterotrimer is composed of a molybdoprotein, a flavoprotein, and an iron-sulfur protein. CO oxidation takes place at the molybdoprotein which contains a 1:1 mononuclear complex of molybdopterin-cytosine dinucleotide and a Mo-ion, along with a catalytically essential S-selanylcysteine. The latter is appropriately positioned in the SeMo-active site by a unique VAYRCSFR active site loop. In H. pseudoflava the arginine preceeding the cysteine in the active site loop is modified to a Cgamma-hydroxy arginine residue which has no obvious function. The substituents in the first coordination sphere of the Mo-ion are the enedithiolate sulfur atoms of the molybdopterin-cytosine dinucleotide, two oxo- and a sulfido-group. Extended X-ray absorption fine structure spectroscopy (EXAFS), along with the crystal structure of CO dehydrogenase (23.2 U mg(-1)) at 1.85 A resolution, have identified a sulfur atom at 2.3 A from the Mo-ion. The sulfur reacts with cyanide yielding thiocyanate. The corresponding inactive desulfo-CO dehydrogenase shows a typical desulfo inhibited-type of Mo-electron paramagnetic resonance (EPR) spectrum. Structural changes at the SeMo-site during catalysis are suggested by the Mo to Se distance of 3.7 A and the Mo-S-Se angle of 113 degrees in the oxidized enzyme which increase to 4.1 A, and 121 degrees, respectively, in the reduced enzyme. The intramolecular electron transport chain in CO dehydrogenase involves the following prosthetic groups and minimal distances: CO-->[Mo of the molybdenum cofactor] - 14.6 A - [2Fe-2S]I - 12.4 A - [2Fe-2S]II - 8.7 A - [FAD].
64 citations
TL;DR: The results are relevant enough to suggest the exploitation of LP-thiocyanate-H2O2 system as an effective agent against many of the disease causing organisms in plants and animals.
62 citations
TL;DR: In this article, four new polymeric complexes [Cd(dmen)(SCN)2]n 1, [cd(deen) 2]n 2, [Ccdrn)(N3]n 3]n 4 and [Cdrn(deen)-N3]-n 4 have been synthesized and characterized by single crystal X-ray diffraction.
Abstract: Four new polymeric complexes [Cd(dmen)(SCN)2]n 1, [Cd(deen)(SCN)2]n 2, [Cd(dmen)(N3)2]n 3 and [Cd(deen)(N3)2]n 4 (dmen = N,N-dimethylethylenediamine and deen = N,N-diethylethylenediamine) have been synthesized and characterized by single crystal X-ray diffraction. The various arrangements of thiocyanate anions give a 2-D polynuclear chain of pseudo sixteen membered rings for 1 and a 1-D polynuclear chain of eight membered rings for 2. The 2-D polymeric sheets of complexes 3 and 4 involve the formation of two different rings, one a twenty membered zigzag ring and the other a four membered square ring. The co-ordination environment of the cadmium atom in all the complexes is distorted octahedral. In the azido-bridged complexes the cadmium(II) ions are linked both by end-on and end-to-end co-ordination, whereas in the thiocyanato-bridged complexes the cadmium(II) ions are bridged only by end-to-end co-ordination.
57 citations
TL;DR: In this article, a synthesis of 1,2-dichalcogenins is presented, including 1, 2-diselenin and 2-selenathiin, both substituted and unsubstituted.
Abstract: Syntheses are presented of the 1,2-dichalcogenins: 1,2-dithiin, 1,2-diselenin, and 2-selenathiin, both substituted and unsubstituted. 1,2-Dithiin and 1,2-diselenin are prepared by reaction of PhCH2XNa (X = S or Se) with 1,4-bis(trimethylsilyl)-1,3-butadiyne followed by reductive cleavage and oxidation. 2-Selenathiin is similarly prepared using a mixture of PhCH2SeNa and PhCH2SNa. Reaction of titanacyclopentadienes with (SCN)2 or (SeCN)2 followed by bis(thiocyanate) or bis(selenocyanate) cyclization affords substituted 1,2-dithiins or 1,2-diselenins, respectively. With S2Cl2, 1,2-dithiins are directly formed from titanacyclopentadienes. Oxidation of 1,2-dithiins and 1,2-diselenins gives the corresponding 1-oxide and, with 1,2-dithiins and excess oxidant, 1,1-dioxides; oxidation of 2-selenathiin gives the 2-oxide. Electrochemical oxidation of 1,2-dichalcogenins, which have a twisted geometry, affords planar radical cations by an EC mechanism. One-electron AlCl3 oxidation of 3,6-diphenyl-1,2-dithiin gives t...
TL;DR: Observations indicate that this enzyme could be involved in the detoxification of reactive thiols produced upon glucosinolate degradation in these plants.
Abstract: The physiological relevance of a novel thiol methyltransferase from cabbage, and its possible role in sulphur metabolism have been investigated. The enzyme was absent from the chloroplast, the site of sulphate reduction, and was localized in the cytosol. Potential substrates were initially screened on the basis of their ability to inhibit the methylation of iodide, a previously known substrate for the enzyme. Thiocyanate, 4,4′-thiobisbenzenethiol, thiophenol, and thiosalicylic acid were identified as possible substrates. Methylation of these thiols by the purified enzyme using [Methyl-3H]S-adenosyl- L-methionine confirmed their nature as substrates. The purified enzyme strongly preferred thiocyanate as a methyl acceptor. The enzyme had Km values of 11, 51, 250 and 746 mmol m−3 for thiocyanate, 4,4′-thiobisbenzenethiol, thiophenol and thiosalicylic acid, respectively. The identity of methylthiocyanate as the product of thiocyanate methylation by the purified enzyme was confirmed by mass spectrometry. The enzyme was strictly associated with glucosinolate-containing plants. Thiol substrates of the enzyme are known products of glucosinolate hydrolysis. Our observations indicate that this enzyme could be involved in the detoxification of reactive thiols produced upon glucosinolate degradation in these plants.
TL;DR: Results suggest that the entire COS produced was easy to diffuse outside the cells and that the evolved COS was re-incorporated to be metabolized by cells.
TL;DR: Excellent global fits of this mechanism to the repetitive-scan data are obtained with rate constants constrained by the Ti(IV) data and published previously in the study of the ClO2/SCN- reaction, in fine agreement with the prior report.
Abstract: The kinetics of the reaction of H2O2 with excess SCN- in acidic media was studied by use of Ti(IV) as an indicator for the concentration of H2O2. Pseudo-first-order behavior was realized by this method, and these data confirm the acid-catalyzed rate law and rate constant reported some 40 years ago for this reaction under conditions of excess H2O2. Under the same conditions except without Ti(IV), repetitive-scan spectra reveal the formation and decay of an intermediate that absorbs in the UV. In the proposed mechanism, HOSCN is produced in the first step and it is converted rapidly to (SCN)2 through its equilibrium reaction with SCN-. The observed intermediate is believed to be (SCN)2, which decays on a longer time scale. Excellent global fits of this mechanism to the repetitive-scan data are obtained with rate constants constrained by the Ti(IV) data and published previously in our study of the ClO2/SCN- reaction. These fits yield a spectrum for (SCN)2 that is characterized by λmax = 297 nm and e297 = 147...
TL;DR: In this paper, a sequential injection analysis (SIA) system was developed for the spectrophotometric determination of thiocyanate as Fe(SCN) 2C.
TL;DR: The proposed method gave recoveries ranging from 95.0 to 105.0% when applied to the determination of polythionates added to hot spring waters, and the detection limits defined at S/N=3 and 230 nm were very low for all anions.
TL;DR: In this paper, an efficient synthesis of phenacyl thiocyanates and azides is described, where Styrenes react with ammonium thiocoyanate and sodium azide in the presence of cerium(IV) ammonium nitrate under an oxygen atmosphere.
TL;DR: The results show conclusively that the redox intermediates formed upon addition of either hydrogen peroxide or hypochlorous acid to native MPO exhibit the same spectral features and reactivities and thus are identical.
Abstract: The reaction of human myeloperoxidase (MPO) with hypochlorous acid (HOCl) was investigated by conventional stopped-flow spectroscopy at pH 5, 7, and 9. In the reaction of MPO with HOCl, compound I is formed. Its formation is strongly dependent on pH. HOCl (rather than OCl-) reacts with the unprotonated enzyme in its ferric state. Apparent second-order rate constants were determined to be 8.1×107 M-1s-1 (pH 5), 2.0×108 M-1s-1 (pH 7) and 2.0×106 M-1s-1 (pH 9) at 15°C. Furthermore, the kinetics and spectra of the reactions of halides and thiocyanate and of physiologically relevant one-electron donors (ascorbate, nitrite, tyrosine and hydrogen peroxide) with this compound I were investigated using the sequential-mixing technique. The results show conclusively that the redox intermediates formed upon addition of either hydrogen peroxide or hypochlorous acid to native MPO exhibit the same spectral features and reactivities and thus are identical. In stopped-flow investigations, the MPO/HOCl system has ...
TL;DR: In this article, three new copper(I) thiocyanato complexes [Cu(NCS)L]n (L=methyl nicotinate 1, ethyl nicotine 2), and [HL][Cu[NCS]2] (HL=H-ethyl isonicotinate 3), have been prepared and characterized by spectroscopic and crystallographic methods.
TL;DR: In this article, the electrocatalysis of the nitrate reduction to nitrite by Cd underpotential deposition on Au(111) was studied by scanning tunneling microscopy (STM).
Abstract: The electrocatalysis of the nitrate reduction to nitrite by Cd underpotential deposition (upd) on Au(111) was studied. The structures of the Cd adlayer underpotentially deposited on a Au(111) surface with nitrate in acidic sodium sulfate electrolyte were investigated by scanning tunneling microscopy (STM). Several ordered adlattices were observed, with the catalytically active structure being a (1 × 1) Cd adlayer. This adlayer exhibited a Moire pattern rotated by 9° from the Au(111) lattice direction. Thiocyanate and ethanethiol were used to investigate the mechanism of the catalysis by the Cd adlayer. The addition of thiocyanate did not affect the nitrate reduction activity. On the other hand, ethanethiol was a poison toward the nitrate reduction. STM images revealed surface roughening due to ethanethiol at the potential of the reduction of nitrate. We suggest that nitrate association with the (1 × 1) Cd adlattice is a requirement for electroreduction activity.
TL;DR: In this article, the spectral changes associated with the chemical interaction between SiO2/Al2O3-stabilized gold nanoparticles and (SCN)2•- are elucidated using time-resolved transient absorption spectroscopy.
Abstract: Pulse radiolytically generated (SCN)2•- radicals bind strongly to the gold nanoparticle surface, with an apparent equilibrium constant of 4.7 × 103 M-1. The resultant complex has a strong absorption band at 390 nm which quickly undergoes chemical changes to yield an oxidation product, [Au(SCN)2]-, with an absorption maximum at 320 nm. The spectral changes associated with the chemical interaction between SiO2/Al2O3-stabilized gold nanoparticles and (SCN)2•- are elucidated using time-resolved transient absorption spectroscopy.
TL;DR: Cyanex 925 is a trialkyl phosphine oxide containing branched alkyl groups as discussed by the authors, which is a possible alternative for hafnium/zirconium separation.
TL;DR: In this paper, it was shown that there is no pH dependence of the carbonate radical reactivity toward SCN −, I −, and Fe(CN) 6 4− above pH 8.5.
TL;DR: The paper illustrates for the first time the use of capillary electrophoresis in studying reaction kinetics and provides a non-laborious way to determine the rate law and the rate constant for the above reaction in the pH range 6-8.
TL;DR: In this paper, quinone methides were produced in aqueous solution by photochemical dehydra- tion of o-hydroxybenzyl alcohols (o-HOC6H4CHROH), and flash photolytic techniques were used to examine their rehydration back to starting substrate as well as their interaction with bromide and thiocyanate ions.
Abstract: Quinone methides were produced in aqueous solution by photochemical dehydra- tion of o-hydroxybenzyl alcohols (o-HOC6H4CHROH; R = H, C6H5, 4-CH3OC6H4), and flash photolytic techniques were used to examine their rehydration back to starting substrate as well as their interaction with bromide and thiocyanate ions. These reactions are acid-cat- alyzed and show inverse isotope effects ( kH+/kD+ < 1), indicating that they occur through preequilibrium protonation of the quinone methide on its carbonyl carbon atom followed by rate-determining capture of the benzyl carbocations so formed by H 2O, Br - , or SCN - . With some quinone methides (R = C6H5 and 4-CH3OC6H4) this acid catalysis could be saturated, and analysis of the data obtained in the region of saturation for the example with R = 4-CH3OC6H4 produced both the equilibrium constant for the substrate protonation step and the rate constant for the rate-determining step. Energy relationships comparing the quinone methides with their benzyl alcohol precursors are derived.
TL;DR: In this article, the authors describe an autocatalytic process for the formation of zerovalent copper compounds in situ using NH4X (X = I, Br or SCN) in the presence of RbI and 18-crown-6.
Abstract: Treatment of zerovalent copper with NH4X (X = I, Br or SCN) in the presence of RbI and 18-crown-6 (18c6), in acetonitrile, in air, afforded a diversity of crystalline products in which halogeno- or pseudo-halogeno-cuprate(I) anions co-precipitate with the geometrically rigid crown ether cation [Rb(18c6)]+. Four complexes [{Rb(18c6)}2MeCN][Cu4I6] 1, [Rb(18c6)][Rb(18c6)(MeCN)3]2[{Rb(18c6)}6Cu4I7][Cu7I10]22, {[Rb(18c6)][Cu3I3Br]}∞3 and {[Rb(18c6)][Cu2(SCN)3]}∞4 have been isolated and characterised. Formation of the copper(I) species here is believed to be an autocatalytic process catalysed by the formation of copper(II) compounds in situ. The anions present in the initial mixture have a profound effect upon metal–halogen framework formation. There is a competition between the strongly co-ordinating anions that leads to the partial or complete replacement of iodine by bromine or thiocyanate in 3 and 4, respectively. Complex 1 contains a discrete disordered [Cu4I6]2− species sandwiched between the [Rb(18c6)]+ cations. The structural motif of 2 consists of ensembles of two [Rb(18c6)(MeCN)3]+ and one [Rb(18c6)]+ cation, the bulky supramolecular cation [{Cs(18c6)}6Cu4I7]3+ and crown-like [Cu7I10]3− clusters in which seven copper atoms describe a hexagonal pyramid. In the mixed halogenocuprate(I) anion [Cu3I3Br]−∞ characterised in 3 all the copper atoms of the polymeric chain lie in the same plane; the halides bridge the alternate sides of the polymer. The Br atoms form bridges between [Cu3I3]n chains and the [Rb(18c6)]+ cations. The ability of the SCN group to act as a bridge gives rise to a one-dimensional structure for 4 which contains two copper(I) atoms each with a different stereochemistry. Complexes 1, 2 and 3 display a change in emission spectrum with temperature in the solid state.
TL;DR: In this paper, highly saline solutions were used to selectively elute copper cyanide and iron cyanide complexes from a variety of anion exchange resins containing different quaternary ammonium functional groups.
TL;DR: The developed chlorine-o-tolidine method is relatively inexpensive and less laborious than the standard (Spectroquant) procedure, and insensitive to the common interferent, cyanate (CNO(-)).
TL;DR: In this article, a pseudo-tetrahedral configuration around the Zn(II) ion with unidentately N(3) bonded heterocycles and halides or thiocyanates (N bonded) in terminal positions was observed.
TL;DR: In this article, N -ethyl-2-aminocyclopentene-1-dithiocarboxylic acid is used as a synthetic carrier for highly efficient and selective transport of Cu(II) ions through a liquid membrane.