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951.
对氯柱硼镁石(2MgO•2B2O3•MgCl2•14H2O)在4.5%H3BO3水溶液40 ℃的溶解及相转化过程进行了动力学研究.对不同时间取出的液相的化学分析及不同阶段分离固相的鉴定结果表明,该复盐在溶解阶段出现与前所报导不同的同步溶解,最终产物是库水硼镁石(2MgO•3B2O3•15H2O).提出了库水硼镁石的形成条件和溶解及相转化动力学机理,利用单纯形优化法配合Runge-Kutta微分方程组数值解法对实验数据进行处理,给出了转化结晶动力学方程. 相似文献
952.
953.
Highly Enantioselective Kinetic Resolution of Axially Chiral BINAM Derivatives Catalyzed by a Brønsted Acid 下载免费PDF全文
Dr. Dao‐Juan Cheng Liang Yan Prof. Dr. Shi‐Kai Tian Ming‐Yue Wu Lu‐Xin Wang Zi‐Li Fan Dr. Sheng‐Cai Zheng Prof. Dr. Xin‐Yuan Liu Prof. Dr. Bin Tan 《Angewandte Chemie (International ed. in English)》2014,53(14):3684-3687
A highly efficient strategy for the kinetic resolution of axially chiral BINAM derivatives involving a chiral Brønsted acid‐catalyzed imine formation and transfer hydrogenation cascade process was developed. The kinetic resolution provides a convenient route to chiral BINAM derivatives in high yields with excellent enantioselectivities. 相似文献
954.
Electrochemical Synthesis of Tetrahexahedral Rhodium Nanocrystals with Extraordinarily High Surface Energy and High Electrocatalytic Activity 下载免费PDF全文
Neng‐Fei Yu Dr. Na Tian Dr. Zhi‐You Zhou Long Huang Jing Xiao Yu‐Hua Wen Prof. Shi‐Gang Sun 《Angewandte Chemie (International ed. in English)》2014,53(20):5097-5101
Noble metal nanocrystals (NCs) enclosed with high‐index facets hold a high catalytic activity thanks to the high density of low‐coordinated step atoms that they exposed on their surface. Shape‐control synthesis of the metal NCs with high‐index facets presents a big challenge owing to the high surface energy of the NCs, and the shape control for metal Rh is even more difficult because of its extraordinarily high surface energy in comparison with Pt, Pd, and Au. The successful synthesis is presented of tetrahexahedral Rh NCs (THH Rh NCs) enclosed by {830} high‐index facets through the dynamic oxygen adsorption/desorption mediated by square‐wave potential. The results demonstrate that the THH Rh NCs exhibit greatly enhanced catalytic activity over commercial Rh black catalyst for the electrooxidation of ethanol and CO. 相似文献
955.
Fan Shi Aaron M. Coffey Assist. Prof. Kevin W. Waddell Assist. Prof. Eduard Y. Chekmenev Assoc. Prof. Boyd M. Goodson 《Angewandte Chemie (International ed. in English)》2014,53(29):7495-7498
A novel variant of an iridium‐based organometallic catalyst was synthesized and used to enhance the NMR signals of pyridine in a heterogeneous phase by immobilization on polymer microbead solid supports. Upon administration of parahydrogen (pH2) gas to a methanol mixture containing the HET‐SABRE catalyst particles and the pyridine, up to fivefold enhancements were observed in the 1H NMR spectra after sample transfer to high field (9.4 T). Importantly, enhancements were not due to any residual catalyst molecules in solution, thus supporting the true heterogeneity of the SABRE process. Further significant improvements may be expected by systematic optimization of experimental parameters. Moreover, the heterogeneous catalyst is easy to separate and recycle, thus opening a door to future potential applications varying from spectroscopic studies of catalysis, to imaging metabolites in the body without concern of contamination from expensive and potentially toxic metal catalysts or accompanying organic molecules. 相似文献
956.
Jinrong Yang Dr. Guosheng Shi Dr. Yusong Tu Prof. Haiping Fang 《Angewandte Chemie (International ed. in English)》2014,53(38):10190-10194
Recent experiments have shown the coexistence of both large unoxidized and oxidized regions on graphene oxide (GO), but the underlying mechanism for the formation of the GO atomic structure remains unknown. Now, using density functional calculations, 52 oxidation pathways for local pyrene structures on GO were identified, and a kinetic profile for graphene oxidation with a high correlation between oxidation loci was proposed, which is different from the conventional view, which entails a random distribution of oxidation loci. The high correlation is an essential nature of graphene oxidation processes and can be attributed to three crucial effects: 1) breaking of delocalized π bonds, 2) steric hindrance, and 3) hydrogen‐bond formation. This high correlation leads to the coexistence of both large unoxidized and oxidized regions on GO. Interestingly, even in oxidized regions on GO, some small areas of sp2‐hybridized domains, similar to “islands”, can persist because of steric effects. 相似文献
957.
Lysosomal pH Rise during Heat Shock Monitored by a Lysosome‐Targeting Near‐Infrared Ratiometric Fluorescent Probe 下载免费PDF全文
Dr. Qiongqiong Wan Prof. Dr. Suming Chen Prof. Dr. Wen Shi Lihong Li Prof. Dr. Huimin Ma 《Angewandte Chemie (International ed. in English)》2014,53(41):10916-10920
Heat stroke is a life‐threatening condition, featuring a high body temperature and malfunction of many organ systems. The relationship between heat shock and lysosomes is poorly understood, mainly because of the lack of a suitable research approach. Herein, by incorporating morpholine into a stable hemicyanine skeleton, we develop a new lysosome‐targeting near‐infrared ratiometric pH probe. In combination with fluorescence imaging, we show for the first time that the lysosomal pH value increases but never decreases during heat shock, which might result from lysosomal membrane permeabilization. We also demonstrate that this lysosomal pH rise is irreversible in living cells. Moreover, the probe is easy to synthesize, and shows superior overall analytical performance as compared to the existing commercial ones. This enhanced performance may enable it to be widely used in more lysosomal models of living cells and in further revealing the mechanisms underlying heat‐related pathology. 相似文献
958.
Engineered Molecular Chain Ordering in Single‐Walled Carbon Nanotubes/Polyaniline Composite Films for High‐Performance Organic Thermoelectric Materials 下载免费PDF全文
Dr. Liming Wang Dr. Qin Yao Dr. Juanxiu Xiao Prof. Kaiyang Zeng Dr. Sanyin Qu Wei Shi Dr. Qun Wang Prof. Lidong Chen 《化学:亚洲杂志》2016,11(12):1804-1810
Single‐walled carbon nanotubes (SWNTs)/polyaniline (PANI) composite films with enhanced thermoelectric properties were prepared by combining in situ polymerization and solution processing. Conductive atomic force microscopy and X‐ray diffraction measurements confirmed that solution processing and strong π–π interactions between the PANI and SWNTs induced the PANI molecules to form a highly ordered structure. The improved degree of order of the PANI molecular arrangement increased the carrier mobility and thereby enhanced the electrical transport properties of PANI. The maximum in‐plane electrical conductivity and power factor of the SWNTs/PANI composite films reached 1.44×103 S cm?1 and 217 μW m?1 K?2, respectively, at room temperature. Furthermore, a thermoelectric generator fabricated with the SWNTs/PANI composite films showed good electric generation ability and stability. A high power density of 10.4 μW cm?2 K?1 was obtained, which is superior to most reported results obtained in organic thermoelectric modules. 相似文献
959.
Cong Wang Zhihua Guo Li Zhang Na Zhang Keying Zhang Bailu Fei Hongyan Wang Jigui Xu Hongwei Shi Miao Qin Lei Ren Xingxing Wu 《中国化学》2016,34(11):1151-1157
Ultralow Pt‐loading Au nanoparticles have been fabricated on the surface of reduced graphene oxide (RGO) by using underpotential deposition (UPD) monolayer redox replacement process. The Pt/Au/RGO modified electrode exhibits an excellent electrocatalytic activity toward catechol and hydroquinone. Under the optimized condition, the separation of peak‐to‐peak between hydroquinone and catechol is 197 mV, which is wide enough to distinguish the isomers of benzenediol. Catechol is detected by the Pt/Au/RGO/GCE with a low detection limit in the presence of hydroquinone. 相似文献
960.
Three solvent‐dependent chiral copper(II) compounds, {[Cu2(bzgluO)2(H2O)2]·4H2O}n ( 1 ), {[Cu2(bzgluO)2(DMSO)2]·H2O}n ( 2 ) and [Cu2(bzgluO)2(DMF)2]n ( 3 ) (H2bzgluO=N‐benzoyl‐L‐glutamic acid) have been synthesized under ambient temperature conditions and characterized by elemental analysis, IR spectra, UV spectra, thermogravimetric analysis, powder X‐ray diffraction (PXRD) and single‐crystal X‐ray diffraction. Compounds 1 and 2 both crystallize in the orthorhombic space group P212121. Compound 3 crystallizes in the tetragonal space group P43. Compound 1 exhibits a ladder‐like 1D chain structure, which is extended by hydrogen‐bonding interactions to form a 3D supramolecular network. Compounds 2 and 3 both give a diamond‐like 3D structure. Besides, there are hydrogen‐bonding interactions in 2 . The structural difference indicates that the solvent system plays a crucial role in modulating structures of coordination compounds. Circular dichroism (CD) and the magnetic properties of the compounds have also been investigated. 相似文献