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61.
62.
The oxidation of a ternary complex of chromium(III), [CrIII(DPA)(Mal)(H2O)2]?, involving dipicolinic acid (DPA) as primary ligand and malonic acid (Mal) as co-ligand, was investigated in aqueous acidic medium. The periodate oxidation kinetics of [CrIII(DPA)(Mal)(H2O)2]? to give Cr(VI) under pseudo-first-order conditions were studied at various pH, ionic strength and temperature values. The kinetic equation was found to be as follows: \( {\text{Rate}} = {{\left[ {{\text{IO}}_{4}^{ - } } \right]\left[ {{\text{Cr}}^{\text{III}} } \right]_{\text{T}} \left( {{{k_{5} K_{5} + k_{6} K_{4} K_{6} } \mathord{\left/ {\vphantom {{k_{5} K_{5} + k_{6} K_{4} K_{6} } {\left[ {{\text{H}}^{ + } } \right]}}} \right. \kern-0pt} {\left[ {{\text{H}}^{ + } } \right]}}} \right)} \mathord{\left/ {\vphantom {{\left[ {{\text{IO}}_{4}^{ - } } \right]\left[ {{\text{Cr}}^{\text{III}} } \right]_{\text{T}} \left( {{{k_{5} K_{5} + k_{6} K_{4} K_{6} } \mathord{\left/ {\vphantom {{k_{5} K_{5} + k_{6} K_{4} K_{6} } {\left[ {{\text{H}}^{ + } } \right]}}} \right. \kern-0pt} {\left[ {{\text{H}}^{ + } } \right]}}} \right)} {\left\{ {\left( {\left[ {{\text{H}}^{ + } } \right] + K_{4} } \right) + \left( {K_{5} \left[ {{\text{H}}^{ + } } \right] + K_{6} K_{4} } \right)\left[ {{\text{IO}}_{4}^{ - } } \right]} \right\}}}} \right. \kern-0pt} {\left\{ {\left( {\left[ {{\text{H}}^{ + } } \right] + K_{4} } \right) + \left( {K_{5} \left[ {{\text{H}}^{ + } } \right] + K_{6} K_{4} } \right)\left[ {{\text{IO}}_{4}^{ - } } \right]} \right\}}} \) where k 6 (3.65 × 10?3 s?1) represents the electron transfer reaction rate constant and K 4 (4.60 × 10?4 mol dm?3) represents the dissociation constant for the reaction \( \left[ {{\text{Cr}}^{\text{III}} \left( {\text{DPA}} \right)\left( {\text{Mal}} \right)\left( {{\text{H}}_{2} {\text{O}}} \right)_{2} } \right]^{ - } \rightleftharpoons \left[ {{\text{Cr}}^{\text{III}} \left( {\text{DPA}} \right)\left( {\text{Mal}} \right)\left( {{\text{H}}_{2} {\text{O}}} \right)\left( {\text{OH}} \right)} \right]^{2 - } + {\text{H}}^{ + } \) and K 5 (1.87 mol?1 dm3) and K 6 (22.83 mol?1 dm3) represent the pre-equilibrium formation constants at 30 °C and I = 0.2 mol dm?3. Hexadecyltrimethylammonium bromide (CTAB) was found to enhance the reaction rate, whereas sodium dodecyl sulfate (SDS) had no effect. The thermodynamic activation parameters were estimated, and the oxidation is proposed to proceed via an inner-sphere mechanism involving the coordination of IO4 ? to Cr(III). 相似文献
63.
Microwave‐Assisted Synthesis of Arylazoaminopyrazoles as Disperse Dyes for Textile Printing 下载免费PDF全文
Tawfik A. Khattab Karima M. Haggag Mohamed H. Elnagdi Amal A. Abdelrahman Sherif Abdelmoez Aly 《无机化学与普通化学杂志》2016,642(13):766-772
The synthesis of heterocyclic azo‐dyes via conventional heating and microwave (MW) heating was investigated. From a sequence of reactions starting from cyanoacetic acid, 4‐arylazo‐2H‐pyrazol‐3‐ylamines and 4‐arylazo‐2‐phenyl‐2H‐pyrazol‐3‐ylamines were obtained. The structures these compounds were obtained by inspection of spectroscopic and analytical techniques including 1H and 13C NMR spectroscopy, IR spectroscopy, mass spectrometry, and elemental analysis. The fastness properties and UV/Vis absorption spectroscopic data of these disperse dyes in printing polyester fabrics were investigated. 相似文献
64.
A composite consisting of chitosan containing azidomethylferrocene covalently immobilized on sheets of reduced graphene oxide was drop-casted on a polyester support to form a screen-printed working electrode that is shown to enable the determination of nitrite by cyclic voltammetry and chronoamperometry. Both reduction and oxidation of nitrite can be accomplished due to the high electron-transfer rate of this electrode. Under optimal experimental conditions (i.e. an applied potential of 0.7 V vs. Ag/AgCl in pH 7.0 solution), the calibration plot is linear in the 2.5 to 1450 μM concentration range, with an ~0.35 μM limit of detection (at a signal-to-noise ratio of 3). The sensor was successfully applied to the determination of nitrite in spiked mineral water samples, with recoveries ranging between 95 and 101 %. 相似文献
65.
Qingran Zhang Richard F. Webster Soshan Cheong Richard D. Tilley Xunyu Lu Rose Amal 《Particle & Particle Systems Characterization》2019,36(1)
The development of highly active and cost‐effective catalyst materials toward electrochemical water splitting is of great importance for converting and storing the intermittent solar energy in the form of hydrogen. Herein, for the first time, an ultrathin Fe and N‐co‐doped carbon nanosheet encapsulated Fe‐doped CoNi alloy nanoparticle (FeCoNi@FeNC) composite is obtained and applied as a bifunctional catalyst for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). This catalyst exhibits prominent catalytic performances for both HER and OER, which only requires overpotentials of 102 and 330 mV, respectively, to reach a current density of 10 mA cm?2 in alkaline media. The high catalytic activity is intrinsically associated with the presence of Fe in both nanosheets and nanoparticles, which has triggered the occurrence of coordinative effects between Fe‐N‐C and FeCoNi that are beneficial for HER and OER, as revealed by electrochemical techniques. In an overall water splitting electrolyzer, FeCoNi@FeNC is employed as both the cathode and anode catalysts, achieving 12 mA cm?2 at 1.63 V for a duration of more than 12 h. 相似文献
66.
Fourier-transform infrared spectroscopy (FTIR) was successfully used for quantitative determination of diethylene glycol in glycerin raw material. In addition to the pure samples of both diethylene glycol and glycerin, nine binary mixtures of the two components with mixing ratios ranging from (70 to 98)%wt were created and studied as a training set. Glycerine showed, thereby, characteristic infrared bands at 1110, 992, 974, and 922?cm?1 while those of diethylene glycol appear at 1085, 887, and 881?cm?1. The quantitative determination of diethylene glycol in binary mixtures with glycerin was achieved upon using the absorbance difference between the 992?cm?1 and the 881?cm?1 as well as between 1110 and 1085?cm?1 bands. With an average %error of 0.60 and 1.74, respectively and a limit of detection down to 0.85%, the created calibration curves from the training set were applied successfully to determine the composition of another eight binary mixtures of the two materials representing a validation set. The method was also applied to aqueous solutions of diethylene glycol and glycerin that contains (25 and 50)%wt water. Once more, training and validation sets of mixtures with different diethylene glycol and glycerin ratios at the two water percentages were prepared and measured. Again, successful determination of diethylene glycol in these aqueous solutions was achieved with an average %error of 0.92 and 0.47, respectively. 相似文献
67.
Nanosized metal deposits on titanium dioxide for augmenting gas-phase toluene photooxidation 总被引:1,自引:0,他引:1
The build-up of intermediate species on the surface of TiO2 during gas-phase toluene (C7H8) photodegradation has been observed to deactivate the photocatalyst. Nanosized metallic deposits on the TiO2 surface may enhance the photocatalytic process and improve photocatalyst performance. In this study, noble (Ag, Au) and platinum
group (Pt, Pd, Rh) metals, at a nominal loading of 0.5 at.%, were deposited onto Degussa P25 TiO2 to enhance photocatalyst performance and inhibit deactivation. Pd, Rh and Au deposits delayed photocatalyst deactivation
by a factor of 2, while Pt deposits delayed photocatalyst deactivation by a factor of 20, when compared with neat TiO2. Ag deposits did not improve photocatalyst activity. Metal deposit performance was related to the work function of each metal,
however, the Pt finding suggested that these effects are not governed solely by this aspect, but factors such as deposit characteristics
and/or thermal catalytic properties of the metals may be influential. 相似文献
68.
Renske M. van der Veen Chris J. Milne Dr. Amal El Nahhas Frederico A. Lima Van‐Thai Pham Jonathan Best Julia A. Weinstein Dr. Camelia N. Borca Dr. Rafael Abela Dr. Christian Bressler Prof. Dr. Majed Chergui Prof. Dr. 《Angewandte Chemie (International ed. in English)》2009,48(15):2711-2714
Metallica : A large contraction of the Pt? Pt bond in the triplet excited state of the photoreactive [Pt2(P2O5H2)4]4? ion is determined by time‐resolved X‐ray absorption spectroscopy (see picture). The strengthening of the Pt? Pt interaction is accompanied by a weakening of the ligand coordination bonds, resulting in an elongation of the platinum–ligand bond that is determined for the first time.
69.
Amal Tarbi El Houssine Atmani Mohammed Amine Sellam Meriem Lougdali Youssef El Kouari Anna Migalska-Zalas 《Optical and Quantum Electronics》2018,50(7):293
The quaternaries \(In_{1 - x} Ga_{x} As_{y} P_{1 - y}\) are the main promising elements for the fabrication of optoelectronic devices. The adjustment of their physical parameters is assumed by the change of the molar fraction \(x\) and \(y\). These parameters can be affected by the variation of temperature and pressure. To make the theoretical diagnosis of these materials, it is fundamental to know the energy gap ‘\(\varvec{E}_{\varvec{g}}\)’ and the lattice parameter ‘\(a\)’, over a wide range of chemical compositions \(0 \le x \le 0.47\) and \(0 \le y \le 1\), at different temperatures and pressures. We show that by using the Artificial Neural Network method optimized by the Levenberg Maquardt algorithm ANN-LM, it is possible to obtain results very close to the experiment. The scatter plot and error calculation show that the ANN-LM model provides more accurate values of the lattice parameter than those calculated by Vegard’s law. On the other hand, the energy gap values \(Eg (x, y, T)\) estimated, using the ANN-LM model, proved to be close to the experimental values that those calculated by the empirical equations. In addition, the ANN-LM method allowed us to estimate with great accuracy the values of the energy gap at different temperatures and pressures \(Eg (P, T)\). Our work provides crucial information on the physical properties of the quaternary without the use of approximations, and without taking into account the hypothesis of a perfect agreement between \(InGaAsP\) and \(InP\) substrate. 相似文献
70.
Uzma Habib Amin Badshah Ulrich Flörke Rizwana Aleem Qureshi Bushra Mirza Nazar-ul-Islam Azeem Khan 《Journal of chemical crystallography》2009,39(10):730-734
Abstract The reaction of Cu(OOCCH3)2·H2O with (2,4-diamino-5-(3′,4′,5′-trimethoxybenzyl) pyrimidine (trimethoprim) in ethanolic solution at 80 °C affords the title
complex which has been characterized by elemental, IR, and NMR (1H and 13C).The crystal structure has been determined by single crystal X-ray diffraction. Compound 1 (C36H48Cu2N8O14) is triclinic, space group P-1 with a = 7.2676(4) ?, b = 11.6721(7) ?, c = 12.8279(8) ?, α = 95.839(1)°, β = 93.456(1)°, γ = 105.541(1)°, Z = 1. Two copper atoms are coordinated directly to each other as well as are held together by four bridging aceto groups.
Each copper atom is also bonded opposite the Cu–Cu vector to a trimethoprim molecule through the N(1) atom of the pyrimidine
ring. Trimethoprim acts as a monodentate ligand through the pyrimidine nitrogen N(1) atom. The complex was screened for the
activity against several bacteria, showing more activity against bacteria as compared to trimethoprim.
Graphical Abstract To enhance the activity of trimethoprim, its derivative was prepared and there bacterial activity against several bacteria
was analyzed.
相似文献