7783-06-4Relevant articles and documents
Factors affecting the hydrogen reduction kinetics of CsHSO4
Ponomareva,Lavrova
, p. 85 - 89 (2009)
The hydrogen reduction of CsHSO4, including in the presence of catalysts, is studied. The main factors affecting the rate of the process are determined. A possible reaction mechanism through the surface hydrated phase is discussed. Experiments
on demand redox buffering by H2S contributes to antibiotic resistance revealed by a bacteria-specific H2S donor
Shukla, Prashant,Khodade, Vinayak S.,Sharathchandra, Mallojjala,Chauhan, Preeti,Mishra, Saurabh,Siddaramappa, Shivakumara,Pradeep, Bulagonda Eswarappa,Singh, Amit,Chakrapani, Harinath
, p. 4967 - 4972 (2017)
Understanding the mechanisms of antimicrobial resistance (AMR) will help launch a counter-offensive against human pathogens that threaten our ability to effectively treat common infections. Herein, we report bis(4-nitrobenzyl)sulfanes, which are activated by a bacterial enzyme to produce hydrogen sulfide (H2S) gas. We found that H2S helps maintain redox homeostasis and protects bacteria against antibiotic-triggered oxidative stress on demand , through activation of alternate respiratory oxidases and cellular antioxidants. We discovered, a hitherto unknown role for this gas, that chemical inhibition of H2S biosynthesis reversed antibiotic resistance in multidrug-resistant (MDR) uropathogenic Escherichia coli strains of clinical origin, whereas exposure to the H2S donor restored drug tolerance. Together, our study provides a greater insight into the dynamic defence mechanisms of this gas, modes of antibiotic action as well as resistance while progressing towards new pharmacological targets to address AMR.
Thio sol-gel synthesis of titanium disulfide thin films and nanoparticles using titanium(IV) alkoxide precursors
Let, Alexandru L.,Mainwaring, David E.,Rix, Colin J.,Murugaraj, Pandiyan
, p. 1428 - 1435 (2007)
Titanium tetraisopropoxide reacts with hydrogen sulfide in butylamine solvent at room temperature to form an amorphous titanium alkoxy-sulfide which can be converted to crystalline titanium disulfide by heat treatment in a flowing hydrogen sulfide gas stream. The reaction has been studied using infrared and Raman spectroscopy, gas chromatography-mass spectrometry, X-ray diffractometry and energy-dispersive X-ray analysis measurements. Based on these studies, it is shown that a partially thiolysed alkoxide precursor forms through the replacement of a limited number of alkoxy groups by hydrosulfide moieties. This alkoxy-hydrosulfide is believed to form following a thiolysis-condensation mechanism similar to the hydrolysis-condensation process that occurs during the corresponding oxide sol-gel reaction. The alkoxy-hydrosulfide species can then be completely thiolysed at 800 °C in a stream of hydrogen sulfide to yield pure, hexagonal titanium disulfide in either film or particulate form.
Titanium sulphide nanoclusters formed within inverse micelles
Mainwaring, David E.,Let, Alexandru L.,Rix, Colin,Murugaraj, Pandiyan
, p. 355 - 358 (2006)
High-quality, nano-sized clusters of TiS2 have been grown successfully inside inverse micellar cages and their optical properties studied. The clusters exhibit large blueshifts in the optical-absorption features with decreasing cluster size due to quantum confinement, affording control of the absorption thresholds and a demonstration of the crossover from band-like to molecule-like spectra as the size of the clusters becomes smaller than that of the exciton in the bulk. Crown Copyright
Desulfurization of the Ni(100) Surface Using Gas-Phase Hydrogen Radicals
Capitano, Adam T.,Gland, John L.
, p. 6573 - 6578 (1999)
Gas-phase hydrogen radicals cause desulfurization of the sulfided Ni(100) surface even for temperatures as low as 120 K, resulting in H2S formation. In contrast, no thermal desulfurization is observed in the presence of coadsorbed hydrogen. During hydrogen radical exposure, sulfur is abstracted from the Ni(100) surface by a sequential Eley-Rideal mechanism. After hydrogen radical exposure, two additional H2S formation pathways involving coadsorbed hydrogen are observed during subsequent heating. In the first pathway, H2S formation is observed at 150 K, involving a partially hydrogenated intermediate formed during gas-phase atomic hydrogen exposure. The second pathway involves addition of desorbing subsurface hydrogen to adsorbed sulfur, leading to H2S formation at 190 K. Both the temperature and coverage dependence of the 150 K pathway support a sequential hydrogen addition mechanism with a sulfhydryl intermediate during temperature-programmed desorption (TPD) studies. Previous H2S decomposition studies on this surface show that the sulfhydryl intermediate is not stable above ～190 K because of thermal dehydrogenation. The temperature dependence of H2S formation and sulfur removal during exposure to the gas-phase hydrogen radical is also consistent with a sulfhydryl intermediate. Above 200 K, no desulfurization is observed during gas-phase hydrogen radical exposure. This thermal dehydrogenation of H2S also depends on the coverage of coadsorbed sulfur. Increasing sulfur coverages inhibits dehydrogenation of both H2S and SH. With higher sulfur coverages, H2S desorption is favored and substantial sulfur is removed during temperature-programmed reaction spectroscopy (TPRS) experiments after low-temperature hydrogen radical exposure. Taken together, the temperature- and coverage-dependent behavior indicates that sulfhydryl is an intermediate for sulfur abstraction. Through control of gas-phase hydrogen radical exposure, vacancies in sulfided nickel layers were generated. Hydrogen chemisorption studies were used to probe these sulfur vacancies. The new, low-temperature hydrogen desorption peak at 230 K corresponds to hydrogen modified by coadsorbed sulfur.
Interaction between certain porphyrins and CdS colloids: A steady state and time resolved fluorescence quenching study
Jhonsi, M. Asha,Kathiravan,Renganathan
, p. 1507 - 1511 (2008)
The interaction between porphyrins namely, meso-tetrakis (4-methoxyphenyl)porphyrin (TMeOPP), protoporphyrin IX (PPIX) and Zinc(II) meso-tetraphenylporphyrin (ZnTPP) with colloidal CdS has been studied by using steady state and time resolved fluorescence quenching measurements. The porphyrins adsorbed on the surface of colloidal CdS due to electrostatic interaction. This adsorption leads to changes in the absorption spectra related to the complex formation. The apparent association constant (Kapp) was in the order of 4.34-5.58 × 105 M-1 from the effect of colloidal CdS on the absorption spectra and 0.64-1.6 × 105 M-1 from fluorescence quenching data. Quenching is attributable mainly to static mechanism through ground state complex formation as confirmed by lifetime measurements.
LATTICE VIBRATION SPECTRA Part LXIV. Raman spectroscopic study of lithium hydrogensulfide LiSH: dynamic disorder and order-disorder phase transition
Beckenkamp, K.,Lutz, H. D.,Jacobs, H.,Metzner, U.
, p. 203 - 213 (1991)
Raman spectra (4000-50 cm-1) of lithium hydrogensulfide are recorded in the range from 70 to 300 K.The temperature dependence of frequencies and halfwidths of the SH- stretching and librational modes yields clear evidence for a disorder-order phase transition at 222 K and thermally activated dynamic disorder of the SH- ions in the room temperature polymorph.Down to 70 K the increasing splitting of the in-plane libration can be interpreted by a Landau-type order parameter.This splitting reflects increasing dynamic interactions (factor group splitting) of adjacent (in ) SH- ions due to the ordering process.The halfwidths of the stretching and out-of-plane librational modes exhibits an Arrhenius-type behaviour.The activation energies derived are 1.9 kJ mol-1 for both vibrations.The activation temperature (230 K) is in good agreement with that of the change of the specific heat at 228 K.The order mechanism and a plausible structure of the ordered phase below 222 K are discussed.
Formation of branched fractal CdS patterns in oligomer LB monolayers: A study using transmission electron microscopy
Li, Lin Song,Jin, Jian,Yu, San,Zhao, Yingying,Zhang, Chengxiang,Li, Tie Jin
, p. 5648 - 5652 (1998)
Transmission electron microscopy images of the treelike fractal aggregates of CdS nanoparticles in amphiphilic oligomer (polymaleic acid with octadecanol ester) LB matrix were observed. The features of these aggregates were developed into the micrometer regime. By changing the ratio between carboxylic groups and hydrocarbon chains, as well as the surface pressure, different fractal CdS patterns could be obtained. These results lead us to propose the mechanism of the formation of branchlike patterns, very much analogous to two-dimensional irreversible fractal-growth models such as diffusion-limited aggregates (DLA). Weak hydrophobic and hydrophilic interaction for interfacial molecular recognition at the organic/inorganic interface had been proposed as providing a possible elucidation for the formation of some aspects of a self-similar fractal-like pattern. At a ratio of 7:1, the fractal dimension was calculated by the box-counting method, and the dominant value was 1.69 ± 0.03, which was in good agreement with two-dimensional DLA.
Synthesis and photolysis of 3-tert-butyl-4-oxy(mercapto)-1,4-dihydropyrazolo[5,1-c][1,2,4]triazines
Ivanov, S. M.,Lyssenko, K. A.,Traven, V. F.
, p. 731 - 738 (2020)
Reactions of 3-tert-butyl- or 3,4-di-tert-butyl-substituted 8-methylpyrazolo[5,1-c][1,2,4]-triazines with trifluoroacetic anhydride afforded 1-(2,2,2-trifluoroacetyl)-1,4-dihydropyrazolo-[5,1-c][1,2,4]triazin-4-yl 2,2,2-trifluoroacetates. The treatment with H2X and RXH (X = O or S; R = Me or Et) of covalent trifluoroacetate that does not contain the But group at the C(4) atom allowed us to synthesize 1-(3-tert-butyl-4-R-pyrazolo[5,1-c][1,2,4]triazin-1(4H)-yl)-2,2,2-trifluoroethan-1-ones. The structure of 4-ethylthio derivative was fully established by the single-crystal X-ray diffraction analysis. The UV irradiation of obtained 2,2,2-trifluoroethan-1-ones leads to the aromatization of triazine ring. The UV photolysis of 1-trifluoroacetyl-4-hydroxy derivative has been proposed as a novel method for the photogeneration of acidity. Antimicrobial and antifungal activities of the synthesized compounds were evaluated.
Synthesis and X-ray diffraction characterization of FeNdSbS4, an analog of berthierite
Gasymov,Gasymova,Aliev
, p. 1095 - 1096 (2004)
A rare-earth-containing analog of the mineral berthierite, with the composition FeNdSbS4, was synthesized for the first time. FeNdSbS4 is isostructural with FeSb2S4 and crystallizes in orthorhombic symmetry (sp. gr. Pbam, Z = 4) with lattice parameters a = 11.395 A, b = 14.136 A, and c = 3.747 A.
