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81.
Graphene Quantum Dots Assembled with Metalloporphyrins for “Turn on” Sensing of Hydrogen Peroxide and Glucose 下载免费PDF全文
Dr. Li Zhang Dong Peng Prof. Ru‐Ping Liang Prof. Jian‐Ding Qiu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(26):9343-9348
Noncovalent and multifunctional hybrids have been generated via π–π stacking and electrostatic interactions by combining the nanometer‐scale graphene structure of graphene quantum dots (GQDs) with FeIII 5,10,15,20‐tetrakis(1‐methyl‐4‐pyridyl)porphine (FeTMPyP). The inner filter effect (IFE) of FeTMPyP on the GQDs results in substantial PL quenching of the GQDs. The quenched PL of GQDs by the FeTMPyP can be switched back “on” in response to the reaction between FeTMPyP and H2O2, which causes rupture of the cyclic tetrapyrrolic nucleus with consequential loss of iron from FeTMPyP, and then proceeds further to produce colorless dipyrroles and monopyrroles. This “turn on” system can be applied for simple and convenient H2O2 sensing and can be further extended to the detection of glucose in combination with the specific catalytic effect of glucose oxidase (GOx) through the oxidation of glucose and formation of H2O2. Because of the inherent synthetic control available for the design of metalloporphyrins, the GQDs‐based optical sensing approach described here has the potential to be highly versatile for other target analytes. 相似文献
82.
Enhanced Photocatalytic Reduction of CO2 to CO through TiO2 Passivation of InP in Ionic Liquids 下载免费PDF全文
Guangtong Zeng Jing Qiu Bingya Hou Haotian Shi Dr. Yongjing Lin Mark Hettick Prof. Ali Javey Prof. Stephen B. Cronin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(39):13502-13507
A robust and reliable method for improving the photocatalytic performance of InP, which is one of the best known materials for solar photoconversion (i.e., solar cells). In this article, we report substantial improvements (up to 18×) in the photocatalytic yields for CO2 reduction to CO through the surface passivation of InP with TiO2 deposited by atomic layer deposition (ALD). Here, the main mechanisms of enhancement are the introduction of catalytically active sites and the formation of a pn‐junction. Photoelectrochemical reactions were carried out in a nonaqueous solution consisting of ionic liquid, 1‐ethyl‐3‐methylimidazolium tetrafluoroborate ([EMIM]BF4), dissolved in acetonitrile, which enables CO2 reduction with a Faradaic efficiency of 99 % at an underpotential of +0.78 V. While the photocatalytic yield increases with the addition of the TiO2 layer, a corresponding drop in the photoluminescence intensity indicates the presence of catalytically active sites, which cause an increase in the electron‐hole pair recombination rate. NMR spectra show that the [EMIM]+ ions in solution form an intermediate complex with CO2?, thus lowering the energy barrier of this reaction. 相似文献
83.
Dr. Georgian Melinte Dr. Veselina Georgieva Dr. Marie‐Anne Springuel‐Huet Dr. Andreï Nossov Prof. Ovidiu Ersen Dr. Flavien Guenneau Prof. Antoine Gedeon Dr. Ana Palčić Dr. Krassimir N. Bozhilov Dr. Cuong Pham‐Huu Prof. Shilun Qiu Dr. Svetlana Mintova Dr. Valentin Valtchev 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(50):18316-18327
The principle aspects and constraints of the dynamics and kinetics of zeolite nucleation in hydrogel systems are analyzed on the basis of a model Na‐rich aluminosilicate system. A detailed time‐series EMT‐type zeolite crystallization study in the model hydrogel system was performed to elucidate the topological and temporal aspects of zeolite nucleation. A comprehensive set of analytical tools and methods was employed to analyze the gel evolution and complement the primary methods of transmission electron microscopy (TEM) and nuclear magnetic resonance (NMR) spectroscopy. TEM tomography reveals that the initial gel particles exhibit a core–shell structure. Zeolite nucleation is topologically limited to this shell structure and the kinetics of nucleation is controlled by the shell integrity. The induction period extends to the moment when the shell is consumed and the bulk solution can react with the core of the gel particles. These new findings, in particular the importance of the gel particle shell in zeolite nucleation, can be used to control the growth process and properties of zeolites formed in hydrogels. 相似文献
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Four recoverable and reusable ionic liquids based on 1,4-diazobicyclo[2.2.2]octane(DABCO) have been synthesized to catalyze the aza-Michael addition of secondary amines to a,b-unsaturated compounds.Among the catalysts tested,[DABCO-PDO][OAc] was found to be most suitable for the reaction of a wide range of cyclic substrates without any solvent at room temperature,and afford the products in good to excellent yields within an appropriate amount of time.The proposed mechanism for the dual activation of the catalyst was supported by experimental results as well as the DFT calculation.In addition,the ionic liquids used can be regenerated and recycled several times without any loss of activity. 相似文献
86.
Redox‐Neutral α‐Allylation of Amines by Combining Palladium Catalysis and Visible‐Light Photoredox Catalysis 下载免费PDF全文
Jun Xuan Ting‐Ting Zeng Zhu‐Jia Feng Qiao‐Hui Deng Prof. Dr. Jia‐Rong Chen Dr. Liang‐Qiu Lu Prof. Dr. Wen‐Jing Xiao Prof. Dr. Howard Alper 《Angewandte Chemie (International ed. in English)》2015,54(5):1625-1628
An unprecedented α‐allylation of amines was achieved by combining palladium catalysis and visible‐light photoredox catalysis. In this dual catalysis process, the catalytic generation of allyl radical from the corresponding π‐allylpalladium intermediate was achieved without additional metal reducing reagents (redox‐neutral). Various allylation products of amines were obtained in high yields through radical cross‐coupling under mild reaction conditions. Moreover, the transformation was applied to the formal synthesis of 8‐oxoprotoberberine derivatives which show potential anticancer properties. 相似文献
87.
The existence of solutions for the 2n-order m-point boundary value problem at resonance is obtained by using the coincidence degree theory of Mawhin.We give an example to demonstrate our result.The interest is that the nonlinear term may be noncontinuous. 相似文献
88.
现有在轨服务的对接机构由于其尺寸大、结构复杂、对接目标单一等局限性因素,无法很好地为后续我国探月工程任务提供有力支撑,且受限于运载能力,对接机构的轻量化也是必不可少的一项环节.为研究可服务于未来月球空间站以及载人登月等高轨道任务的对接机构,设计了一种新型抱爪式对接机构,其采用异体同构周边式构型,可以实现主/被动飞行器之间的互换.利用 V 型槽与爪钩等结构部件实现飞行器对接过程中的捕获以 及能量消耗功能,从而实现两飞行器之间的稳固联接.该对接机构具备尺寸小、重量轻、结构简单、功能易实现等优势. 对其捕获缓冲系统进行了动力学分析,计算了缓冲元器件的参数对其捕获性能的影响,在 ADAMS 完成了数字虚拟样机的建立,结合实际两种典型的对接初始条件工况进行了仿真研究.研究结果表明,两种工况下的对接过程能量消耗满足设计要求,能够以较小的 V 型槽的碰撞力完成捕获,结果证明了捕获缓冲系统的可行性以及该构型对接机构具备较好实现任务的能力. 相似文献
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