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941.
942.
Eva Balentova Sandrine Lamandé-Langle David Thonon Christian Lemaire Yves Chapleur 《Journal of fluorine chemistry》2011,132(4):250-257
Two new silicon-based prosthetic groups, derived from 3-[ethoxybis(1-methylethyl)silyl]propanamine, have been prepared in good yields. These silicon groups bearing an acid or an azide group were coupled to a model tripeptide (Leu-Gly-Gly) either through a classical amide bond formation or through “click chemistry” via the Huisgen cycloaddition. The radiolabelling with fluorine-18 by substitution of the ethoxy group at silicon has been carried out with success in 51-54% decay corrected radiochemical yields. Radiolabelled peptides were easily prepared by direct 18F-fluorination of the silicon-bearing tripeptide or by coupling the peptide with a radiolabelled silicon-based prosthetic group. Their stabilities in physiological medium were studied and proved poor. 相似文献
943.
944.
Electrochemical Properties of Substituted 2‐Methyl‐1,4‐Naphthoquinones: Redox Behavior Predictions
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Dr. Mourad Elhabiri Pavel Sidorov Elena Cesar‐Rodo Dr. Gilles Marcou Dr. Don Antoine Lanfranchi Dr. Elisabeth Davioud‐Charvet Dr. Dragos Horvath Prof. Alexandre Varnek 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(8):3415-3424
In the context of the investigation of drug‐induced oxidative stress in parasitic cells, electrochemical properties of a focused library of polysubstituted menadione derivatives were studied by cyclic voltammetry. These values were used, together with compatible measurements from literature (quinones and related compounds), to build and evaluate a predictive structure–redox potential model (quantitative structure–property relationship, QSPR). Able to provide an online evaluation (through Web interface) of the oxidant character of quinones, the model is aimed to help chemists targeting their synthetic efforts towards analogues of desired redox properties 相似文献
945.
Jimmy A. van Rijn Marieke C. Guijt Dwight de Vries Elisabeth Bouwman Eite Drent 《应用有机金属化学》2011,25(3):212-219
The scope of the dehydrative allylation reaction using allyl alcohol as allyl donor with [RuCp(PP)]+ complexes as catalysts is explored. Aliphatic alcohols are successfully allylated with allyl alcohol or diallyl ether, obtaining high selectivity for the alkyl allyl ether. The reactivity of aliphatic alcohols is in the order of primary > secondary ? tertiary. The tertiary alcohol 1‐adamantanol reacts extremely slowly in the absence of strong acid, but when HOTs is added, reasonable yields of 1‐adamantyl allyl ether are obtained. The alkyl allyl ether is found to be the thermodynamically favored product over diallyl ether. Apart from alcohols, thiols and indole are also efficiently allylated, while aniline acts as a catalyst inhibitor. Allylation reactions with various substituted allylic alcohols give products with retention of the substitution pattern. It is proposed that a Ru(IV) σ‐allyl species plays a key role in the mechanism of these allylation reactions. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
946.
Nicolas Coudurier Mikhail Chubarov Raphaël Boichot Frderic Mercier Elisabeth Blanquet Roman Reboud Sabine Lay Alexandre Crisci Stphane Coindeau Thierry Encinas Michel Pons 《Crystal Research and Technology》2016,51(3):231-238
Boron Nitride is a promising group 13–group 15 compound material that exhibits various interesting properties like wide band gap, chemical stability, attractive mechanical properties and other. The growth behavior of this material has not been investigated in sufficient details to tailor properties of the resulting films. In this work we present the results on the growth of turbostratic boron nitride (t‐BN) thin films at a relatively high growth rate of 3 μm/h with the aim to investigate the potential use of boron trichloride in combination with ammonia as precursors for growth. Deposition experiments were conducted in a vertical cold wall high temperature chemical vapor deposition reactor in the temperature range 1000°C–1700°C depending on the substrate used. Templates of w‐AlN (0001), 4° off‐cut 4H‐SiC (0001), Cr (110) and W (110) were employed as substrates for the BN growth. As‐grown BN layers were characterized by Scanning Electron Microscopy, X‐Ray Diffraction, Electron Diffraction and Raman Spectroscopy. The results indicate that temperature and N/B ratio have a great influence on the crystallinity of the deposited films. For AlN and SiC substrates, a temperature of 1600°C and N/B ratio in range between 3 and 7.5 were identified as the best parameters for the growth of a 2 μm thick t‐BN layer with a spacing between basal planes of about 3.36 Å compare to the 3.33 Å spacing between basal planes of hexagonal or rhombohedral BN (h‐BN or r‐BN). For Cr and W substrates which have a lower mismatch with h‐BN (1 and 8.8 %), layers of t‐BN were deposited at much lower temperature (1000°C–1150°C) with a spacing between basal planes of 3.5 Å and morphology similar to that observed on SiC substrates. We obtained t‐BN layers with in plane strong disorder but out of plane orientation (c‐axis normal to the surface). 相似文献
947.
Elisabeth Köbis 《Optimization》2017,66(12):1991-2005
We introduce several variable order relations to compare sets in a linear topological space and we consider set optimization problems equipped with these variable ordering structures. By considering a set approach, we introduce characterizations for optimal solutions and we provide a kind of vectorization result to obtain solutions of set optimization problems equipped with the introduced variable order relations. 相似文献
948.
Deepa Sritharan Abraham Simpson Chen Prabhath Aluthgama Bilal Naved Elisabeth Smela 《Electrophoresis》2015,36(20):2622-2629
For electroosmotic pumping, a large direct‐current (DC) electric field (10+ V/cm) is applied across a liquid, typically an aqueous electrolyte. At these high voltages, water undergoes electrolysis to form hydrogen and oxygen, generating bubbles that can block the electrodes, cause pressure fluctuations, and lead to pump failure. The requirement to manage these gases constrains system designs. This article presents an alternative polar liquid for DC electrokinetic pumping, propylene carbonate (PC), which remains free of bubbles up to at least 10 kV/cm. This offers the opportunity to create electrokinetic devices in closed configurations, which we demonstrate with a fully sealed microfluidic hydraulic actuator. Furthermore, the electroosmotic velocity of PC is similar to that of water in PDMS microchannels. Thus, water could be substituted by PC in existing electroosmotic pumps. 相似文献
949.
Dr. Shenglai Yao Dr. Peter Hrobárik Dipl.‐Chem. Florian Meier Dipl.‐Chem. Robert Rudolph Dr. Eckhard Bill Dr. Elisabeth Irran Prof. Dr. Martin Kaupp Prof. Dr. Matthias Driess 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(4):1246-1253
A unique heterobimetallic disulfur monoradical, complex 2 , with a diamond‐shaped {NiS2Pt} core has been synthesized by two‐electron reduction of a supersulfido‐(nacnac)nickel(II) complex (nacnac=β‐diketiminato) with [Pt(Ph3P)2(η2‐C2H4)] as a platinum(0) source and isolated in 82 % yield. Strikingly, the results of DFT calculations in accordance with spectroscopic (EPR, paramagnetic NMR) and structural features of the complex revealed that the bonding situation of the S2 ligand is between the elusive “half‐bonded” S2 radical trianion (${{\rm S}{{{{\bullet}}3- \hfill \atop 2\hfill}}}$ ) and two separated S2? ligands. Accordingly, the NiII center is partially oxidized, whereas the PtII site is redox innocent. The complex can be reversibly oxidized to the corresponding Ni,Pt‐disulfido monocation, compound 3 , with a S? S single bond, and reacts readily with O2 to form the corresponding superoxonickel(II) and disulfidoplatinum(II) ( 4 ) complexes. These compounds have been isolated in crystalline form and fully characterized, including IR and multi‐nuclear NMR spectroscopy as well as ESI mass spectrometry. The molecular structures of compounds 2 – 4 have been confirmed by single‐crystal X‐ray crystallography. 相似文献
950.
Arne Wagner Dr. Elisabeth Kaifer Prof. Dr. Hans‐Jörg Himmel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(23):7395-7409
The coordination chemistry of the doubly base‐stabilised diborane(4), [HB(hpp)]2 (hpp=1,3,4,6,7,8‐hexahydro‐2H‐pyrimido‐[1,2‐a]pyrimidinate), was extended by the synthesis of new late transition‐metal complexes containing CuI and RhI fragments. A detailed experimental study was conducted and quantum‐chemical calculations on the metal–ligand bonding interactions for [HB(hpp)]2 complexes of Group 6, 9, 11 and 12 metals revealed the dominant B? H? M interactions in the case of early transition‐metal fragments, whereas the B? B? M bonding prevails in the case of the late d‐block compounds. These findings support the experimental results as reflected by the IR and NMR spectroscopic parameters of the investigated compounds. DFT calculations on [MeB(hpp)]2 and model reactions between [B2H4 ? 2NMe3] and [Rh(μ‐Cl)(C2H4)2] showed that the bicyclic guanidinate allows in principle for an oxidative addition of the B? B bond. However, the formation of σ‐complexes is thermodynamically favoured. The results point to the selective B? H or B? B bond‐activation of diborane compounds by complexation, depending on the chosen transition‐metal fragment. 相似文献