Diazoles y triazoles derivados del extracto de aceite de ricino: síntesis, efecto hipoglucémico, potencial antioxidante y actividad antimicrobiana

The ricinoleate triglyceride was extracted from castor-oil seeds grown in Algeria and isolated by catalytically methanolyse to methyl ricinoleate. Six diazole and triazole derivatives of ricinoleic acid were synthesized and characterized: 1,3,4-oxadiazole-5-thione (4); 1,3,4-thiadiazole-5-thione (5); 4-N-amino-1,2,4-triazole-5-thiol (7); 1,2,4-triazole-5-thione (9); 5-amino-1,3,4-oxadiazole (10) and 5-amino-1,3,4-thiadiazole (11). The antibacterial and antifungal screening data of synthesized compounds showed appreciable inhibition and among them, 5, 7 and 8 showed more inhibition on Gram positive Enterococcus faecalis than reference ampiciline; while compounds 1, 7, 8, 10 and 11 showed competitive antifungal effects compared to reference amphotericin B. In addition, all synthesized compounds (1-11) showed competitive antioxidant properties, particularly compounds 7 at 125, 250, 500 and 1000 μg/mL and compounds 4, 5 and 9 at a concentration of 1000 μg/mL. The intermediate compounds 1, 2 and 8 showed anti-α-amylase activity at various concentrations in the range of IC50 = (120.25 ± 1.17 - 130.42 ± 2.48). Oxadiazole 4 showed the best α-amylase inhibition by 78.5% at a concentration of 1000 μg/mL.Los triglicéridos de ricinoleico se extrajeron de semillas de aceite de ricino cultivadas en Argelia y se sintetizó catalíticamente con metanolisis el ricinoleato de metilo. Seis derivados de diazoles y triazoles de ácido ricinoleico se han sintetizado y caracterizado: 1,3,4-oxadiazol-5-tiona (4), 1,3,4-tiadiazol-5-tiona (5), 4-N-amino-1,2,4-triazol-5-tiol (7), 1,2,4-triazol-5-tiona (9), 5-amino-1,3,4-oxadiazol (10) y 5-amino-1,3,4-tiadiazol (11). Los datos de detección antibacteriana y antifúngica de los compuestos sintetizados mostraron una inhibición apreciable, entre ellos, los compuestos 5, 7 y 8 mostraron más inhibición en Enterococcus faecalis Gram positivo que la ampicilina de referencia. Mientras que los compuestos 1, 7, 8, 10 y 11 mostraron una influencia antifúngica competitiva en comparación con la anfotericina de referencia B. Como todos los compuestos sintetizados (1-11) mostraron propiedades antioxidantes competitivas, particularmente los compuestos 7, a 125, 250, 500 y 1000 μg/mL también compuestos 4, 5 y 9 a una concentración de 1000 μg/mL. Los compuestos intermedios 1, 2 y 8 mostraron actividad anti-α-amilasa a diversas concentraciones en el rango de IC50 = (120.25 ± 1.17 - 130.42 ± 2.48). El oxadiazol 4 mostró la mejor inhibición de la α-amilasa en un 78.5% a una concentración de 1000 μg/mL

Physical and photoelectrochemical properties of spherical nanoparticles of α-AgBiS 2

International audienceWe have investigated the physical and photo electrochemical properties of α-AgBiS2 (schapbachite), synthesized from Bi2S3 and Ag2S in evacuated Pyrex ampoule at 550 °C. The precursors are prepared by precipitation from nitrates in ethylene glycol using thiourea as complexing agent and sulfide source. AgBiS2 crystallizes in a rock salt structure (Fm-3m). The transmission electron micrograph shows spherical nanoparticles with an average size of ~ 30 nm, a value very close to that obtained from the Williamson-Hall plot of the XRD powder pattern (33.06±1.28 nm). HRTEM gives inter reticular distance of 0.33 nm, a value in excellent agreement with that of the SAED analysis (d111=0.3276 nm). The diffuse reflectance spectrum indicates a direct optical transition of 0.89 eV. The thermal variation of the electrical conductivity is characteristic of semiconducting behavior with activation energy of 0.20 eV, electron mobility (µ300K) of 2.43 × 10−4 cm2 V−1 s−1 and an effective mass of 2.88 mo. The intensity-potential J(V) curve in alkaline medium (pH 10.2) shows a good electrochemical stability. The dark capacitance (C−2-V) exhibits a linear behavior, characteristic of n-type conduction (dC−2/dE>0), from which a flat band potential of 0.33 VSCE and an electrons density of 2.57 × 1021 cm−3 are determined. The valence band derives from S2−: 3p states while the conduction band is made up mainly of Ag+: 5 s orbital. The electrochemical impedance spectroscopy (EIS), measured in the dark and under illumination over the frequency range (10−3−105 Hz), indicates the contribution of both the bulk and grain boundaries.Graphical abstrac

Improved activity of SnO for the photocatalytic oxygen evolution

SnO prepared by soft chemistry exhibits a black color and semiconducting properties. The X-ray diffraction indicates a tetragonal symmetry (SG: P4/nmm) with nano crystallites of an average size of 85 nm. The forbidden band, determined from the diffuse reflectance is found to be 1.46 eV. The electrical conductivity occurs by polaron hopping and follows an Arrhenius type law with activation energy of 0.21 eV, the change in the slope at 526 K is attributed to the oxidation to SnO2. The photo-electrochemical study shows n type conduction with a flat band potential of −0.45 V, close to the photocurrent onset potential (−0.40 V). The electrochemical impedance spectroscopy shows the bulk contribution of SnO (Rb = 1.7 kΩ cm2) and decreases down to 1.89 kΩ cm2 under illumination. The photocatalytic properties have been evaluated for the first time for to the oxygen evolution. The valence band, deriving from Sn2+: 5p orbital with a potential (−0.80 VSCE/5.55 eV), is suitably positioned with respect to O2/H2O level (∼0.6 VSCE), leading to water oxidation under visible light. The best performance occurs at pH ∼ 7 with an oxygen liberation rate of 23 µmol mL h−1 (mg catalyst)−1 and a quantum efficiency of 1.2%. An improvement of ∼13% is observed on the system SnO/clay

A new hetero-junction p-CuO/n-ZnO for the removal of amoxicillin by photocatalysis under solar irradiation

International audienceThe main objective of this study was to evaluate the efficiency of a new hetero-junction p-CuO/n-ZnO assisted photo-catalytic process for the degradation of amoxicillin (AMX). The catalysts is synthesized by chemical route and characterized by X-ray diffraction, scanning electron microscopy (SEM), thermal analysis, BET specific surface area and photo-electrochemistry. The initial AMX concentration, photo-catalyst nature, catalyst dose and initial pH of the solution were optimized in order to evaluate the mineralization extent. AMX (50 mg/l) was almost entirely removed after 4 h of exposure to solar irradiation at pH similar to 11, by using the hetero-junction ZnO/CuO (50:50 wt%). The final AMX concentration was determined by high performance liquid chromatography (HPLC) equipped with a photodiode array detector. The analysis of NO(3)(-)and SO42- released by the degradation reaction were quantified by ionic chromatography and the total organic carbon (TOC) indicated a high mineralization degree of AMX. Kinetic analysis suggested that the AMX degradation obeys to a pseudo-first-order with a rate constant of 9.95 x 10(-3) min(-1). Finally, the application of this method was extended to real effluents. (C) 2016 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved

Photo-electrochemical properties of p-type AgCoO2 prepared by low temperature method

WOS:000454537700024AgCoO2 prepared by co-precipitation at low temperature (similar to 80 degrees C) is characterized by physical and photo-electrochemical techniques. The X-ray diffraction shows broad peaks with a particle size of similar to 20 nm and a specific surface area of similar to 28 m(2) g(-1). The forbidden band (1.33 eV) is due to Ag+ : d -> d transition, further transition at 4.50 eV is assigned to the charge transfer. The transport properties, measured up to 650 K, indicate intrinsic conductivity: sigma = sigma(o) exp{- 0.24 eV/kT (Omega-cm)(-1)}, supporting a phonon assisted conduction mechanism. An exchange current density of 1.27 mA cm(-2) in Na2SO4 (0.1 M) solution is consistent with the electrochemical stability up to 0.8 V-SCE. The capacitance measurement (C-2 - E) indicates p type conduction, with a flat band potential (E-fb) of 0.26 V-SCE and a holes density (N-A) of 7.38 x 10(19) cm(-3) due to the oxygen insertion in the layered lattice. The electrochemical impedance spectroscopy (EIS) data, recorded in the range (1 mHz - Hz), reveals a predominant bulk contribution with a low depletion angle of 3 degrees and a pseudo capacitive behavior. As application, AgCoO2 is tested for the hydrogen production upon visible illumination owing to the potential of its conduction band (-0.83 V-SCE), less cathodic than that of H2O/H-2 (similar to -0.5 V-SCE). H-2 evolution rate of 79 mu mol g(-1) min(-1) is determined at neutral pH with a quantum yield of 1.92% in presence of NO2 as hole scavenger; no Ag deposition was observed after photocatalysis.Faculty of Chemistry (USTHB) Algiers [E00220140035]The work was supported by the Faculty of Chemistry (USTHB) Algiers under the Project No E00220140035

Effect of reducing gas on the hydrogen production by thermo-oxidation of water over 1%Rh/Ce0.6Zr0.4O2

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