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441.
Dr. Katia Nchimi‐Nono Parastoo Dalvand Dr. Kuldeep Wadhwa Selbi Nuryyeva Shaikha Alneyadi Dr. Thirumurugan Prakasam Dr. Albert C. Fahrenbach Prof. John‐Carl Olsen Dr. Zouhair Asfari Carlos Platas‐Iglesias Dr. Mourad Elhabiri Prof. Ali Trabolsi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(24):7334-7344
Suppression of the dimerization of the viologen radical cation by cucurbit[7]uril ( CB7 ) in water is a well‐known phenomenon. Herein, two counter‐examples are presented. Two viologen‐containing thread molecules were designed, synthesized, and thoroughly characterized by 1H DOSY NMR spectrometry, UV/Vis absorption spectrophotometry, square‐wave voltammetry, and chronocoulometry: BV 4+, which contains two viologen subunits, and HV 12+, which contains six. In both threads, the viologen subunits are covalently bonded to a hexavalent phosphazene core. The corresponding [3]‐ and [7]pseudorotaxanes that form on complexation with CB7 , that is, BV 4+?( CB 7)2 and HV 12+?( CB 7)6, were also analyzed. The properties of two monomeric control threads, namely, methyl viologen ( MV 2+) and benzyl methyl viologen ( BMV 2+), as well as their [2]pseudorotaxane complexes with CB7 ( MV 2+? CB7 and BMV 2+? CB7 ) were also investigated. As expected, the control pseudorotaxanes remained intact after one‐electron reduction of their viologen‐recognition stations. In contrast, analogous reduction of BV 4+?( CB 7)2 and HV 12+?( CB 7)6 led to host–guest decomplexation and release of the free threads BV 2( . +) and HV 6( . +), respectively. 1H DOSY NMR spectrometric and chronocoulometric measurements showed that BV 2( . +) and HV 6( . +) have larger diffusion coefficients than the corresponding [3]‐ and [7]pseudorotaxanes, and UV/Vis absorption studies provided evidence for intramolecular radical‐cation dimerization. These results demonstrate that radical‐cation dimerization, a relatively weak interaction, can be used as a driving force in novel molecular switches. 相似文献
442.
Seyed Mostafa Ebrahimi Mohammad Mahdavi Saeed Emami Mina Saeedi Mehdi Asadi Loghman Firoozpour 《合成通讯》2014,44(5):665-673
A novel and simple method for the green one-pot synthesis of anthranilamide Schiff bases is described. The reported Schiff bases are obtained via the reaction of isatoic anhydride, amines, and aromatic aldehydes in water at room temperature, without using any catalysts. No cyclization toward 2,3-dihydro-4(1H)-quinazolinones occurred in this method and anthranilamide Schiff bases were produced exclusively. This approach offers a green method to prepare the medicinally important Schiff base sirtinol and other bioactive anthranilamide Schiff bases.
[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.] 相似文献
443.
In this work we describe the first report for the determination of promazine using a nanostructuremodified ionic liquid carbon paste electrode in aqueous solutions. To achieve this goal, a novel modified carbon paste electrode using ZnO nanoparticles and 1-methyl-3-butylimidazolium bromide as a binder(ZnO/NPs/ILs/CPE) was fabricated. The oxidation peak potential of promazine at the surface of the ZnO/NPs/ILs/CPE appeared at 685 m V, which was about 65 m V lower than the oxidation potential at the surface of CPE under similar conditions. Also, the peak current was increased to about 4.0 times higher at the surface of ZnO/NPs/ILs/CPE compared to that of CPE. The linear response range and detection limit were found to be 0.08–450 and 0.04 mmol/L, respectively. The modified electrode was successfully used for the determination of promazine in real samples with satisfactory results. 相似文献
444.
Research on Chemical Intermediates - This article aims at Red 2G (R2G) preconcentration via dispersive magnetic solid-phase extraction, prior to its determination by a UV–visible... 相似文献
445.
Khah Melika Hejazi Jamshidi Parastoo Shemirani Farzaneh 《Research on Chemical Intermediates》2021,47(9):3867-3881
Research on Chemical Intermediates - A magnetic solid phase extraction method is presented to preconcentrate Pb(II), Cd(II), Ni(II) and Zn(II) simultaneously. The adsorbent (mMoS2-CS), consisting... 相似文献
446.
The mechanical response and fracture of metal sandwich panels subjected to multiple impulsive pressure loads (shocks) were investigated for panels with honeycomb and folded plate core constructions. The structural performance of panels with specific core configurations under multiple impulsive pressure loads is quantified by the maximum transverse deflection of the face sheets and the core crushing strain at mid-span of the panels. A limited set of simulations was carried out to find the optimum core density of a square honeycomb core sandwich panels under two shocks. The panels with a relative core density of 4%–5% are shown to have minimum face sheet deflection for the loading conditions considered here. This was consistent with the findings related to the sandwich panel response subjected to a single intense shock. Comparison of these results showed that optimized sandwich panels outperform solid plates under shock loading. An empirical method for prediction of the deflection and fracture of sandwich panels under two consecutive shocks – based on finding an effective peak over-pressure – was provided. Moreover, a limited number of simulations related to response and fracture of sandwich panels under multiple shocks with different material properties were performed to highlight the role of metal strength and ductility. In this set of simulations, square honeycomb sandwich panels made of four steels representing a relatively wide range of strength, strain hardening and ductility values were studied. For panels clamped at their edge, the observed failure mechanisms are core failure, top face failure and tearing at or close to the clamped edge. Failure diagrams for sandwich panels were constructed which reveal the fracture and failure mechanisms under various shock intensities for panels subjected to up to three consecutive shocks. The results complement previous studies on the behavior and fracture of these panels under high intensity dynamic loading and further highlights the potential of these panels for development of threat-resistant structural systems. 相似文献