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991.
Photochemically Engineering the Metal–Semiconductor Interface for Room‐Temperature Transfer Hydrogenation of Nitroarenes with Formic Acid 下载免费PDF全文
Dr. Xin‐Hao Li Yi‐Yu Cai Ling‐Hong Gong Dr. Wei Fu Dr. Kai‐Xue Wang Dr. Hong‐Liang Bao Dr. Xiao Wei Dr. Jie‐Sheng Chen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(50):16732-16737
A mild photochemical approach was applied to construct highly coupled metal–semiconductor dyads, which were found to efficiently facilitate the hydrogenation of nitrobenzene. Aniline was produced in excellent yield (>99 %, TOF: 1183) using formic acid as hydrogen source and water as solvent at room temperature. This general and green catalytic process is applicable to a wide range of nitroarenes without the involvement of high‐pressure gases or sacrificial additives. 相似文献
992.
Cube‐in‐Cube Hollow Cu9S5 Nanostructures with Enhanced Photocatalytic Activities in Solar H2 Evolution 下载免费PDF全文
Miao Xu Min Wang Tiannan Ye Na Liang Lun Jin Dr. Jiantao Zai Prof. Xuefeng Qian 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(42):13576-13582
Hydrogen produced from water under solar energy is an ideal clean energy source, and the efficiency of hydrogen production usually depends on the catalytic systems based on new compounds and/or a unique nanostructure. Herein, well‐defined cube‐in‐cube hollow Cu9S5 nanostructures have been successfully prepared with Cu2O nanocubes and CS2 as precursors, and single‐shell hollow Cu9S5 nanocubes could be obtained by replacing CS2 with Na2S. The formation mechanism of cube‐in‐cube hollow nanostructures has been proposed based on the Kirkendell effect and an outward self‐assembly process. Further studies revealed that the cube‐in‐cube hollow Cu9S5 nanostructures exhibited better photocatalytic activity toward solar H2 evolution and would be a promising photocatalyst in the solar hydrogen industry. 相似文献
993.
Cerium‐Based M4L4 Tetrahedra as Molecular Flasks for Selective Reaction Prompting and Luminescent Reaction Tracing 下载免费PDF全文
Yang Jiao Dr. Jian Wang Dr. Pengyan Wu Liang Zhao Dr. Cheng He Jing Zhang Prof. Chunying Duan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(8):2224-2231
The application of metal–organic polyhedra as “molecular flasks” has precipitated a surge of interest in the reactivity and property of molecules within well‐defined spaces. Inspired by the structures of the natural enzymatic pockets, three metal–organic neutral molecular tetrahedral, Ce‐TTS, Ce‐TNS and Ce‐TBS (H6TTS: N′,N′′,N′′′‐nitrilotris‐4,4′,4′′‐(2‐hydroxybenzylidene)‐benzohydrazide; H6TNS: N′,N′′,N′′′‐nitrilotris‐6,6′,6′′‐(2‐hydroxybenzylidene)‐2‐naphthohydrazide; H6TBS: 1,3,5‐ phenyltris ‐4,4′,4′′‐(2‐hydroxybenzylidene)benzohydrazide), which exhibit different size of the edges and cavities, were achieved through self‐assembly by incorporating robust amide‐containing tridentate chelating sites into the fragments of the ligands. They acted as molecular flasks to prompt the cyanosilylation of aldehydes with excellent selectivity towards the substrates size. The amide groups worked as trigger sites and catalytic driven forces to achieve efficient guest interactions, enforcing the substrates proximity within the cavity. Experiments on catalysts with the different cavity radii and substrates with the different molecular size demonstrated that the catalytic performance exhibited enzymatical catalytic mechanism and occurred in the molecular flask. These amides were also able to amplify guest‐bonding events into the measurable outputs for the detection of concentration variations of the substrates, providing the possibility for metal–organic hosts to work as smart molecular flasks for the luminescent tracing of catalytic reactions. 相似文献
994.
Efficient Copper‐Catalyzed Direct Intramolecular Aminotrifluoromethylation of Unactivated Alkenes with Diverse Nitrogen‐Based Nucleophiles 下载免费PDF全文
Dr. Jin‐Shun Lin Ya‐Ping Xiong Can‐Liang Ma Li‐Jiao Zhao Prof. Dr. Bin Tan Prof. Dr. Xin‐Yuan Liu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(5):1332-1340
A mild, convenient, and step‐economical intramolecular aminotrifluoromethylation of unactivated alkenes with a variety of electronically distinct, nitrogen‐based nucleophiles in the presence of a simple copper salt catalyst, in the absence of extra ligands, is described. Many different nitrogen‐based nucleophiles (e.g., basic primary aliphatic and aromatic amines, sulfonamides, carbamates, and ureas) can be employed in this new aminotrifluoromethylation reaction. The aminotrifluoromethylation process allows straightforward access to diversely substituted CF3‐containing pyrrolidines or indolines, in good to excellent yields, through a direct difunctionalization strategy from the respective acyclic starting materials. Mechanistic studies were conducted and a plausible mechanism was proposed. 相似文献
995.
Tuning Thiophene with Phosphorus: Synthesis and Electronic Properties of Benzobisthiaphospholes 下载免费PDF全文
Yunyan Qiu Joshua C. Worch Danielle N. Chirdon Aman Kaur Andrew B. Maurer Samuel Amsterdam Christopher R. Collins Prof. Tomislav Pintauer Prof. David Yaron Prof. Stefan Bernhard Prof. Kevin J. T. Noonan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(25):7746-7751
1,4‐Dimercapto‐2,5‐diphosphinobenzene and 3,6‐bis(hexyloxy)‐1,4‐dimercapto‐2,5‐diphosphinobenzene were synthesized and combined with various acid chlorides to obtain a series of benzobisthiaphospholes. Electrochemical and photophysical properties of the substituted benzobisthiaphospholes have been evaluated, and the observed reductions are more facile than the related benzothiaphospholes and 2,6‐diphenylbenzobisthiazole. A benzobisthiaphosphole with C6H4‐p‐CN substituents was reduced at E1/2=?1.08 V (vs. saturated calomel electrode (SCE)). X‐ray diffraction data for several of these phosphorus heterocycles has been obtained, and DFT calculations at the B3LYP level have been performed. 相似文献
996.
Copper‐Catalyzed One‐Pot Denitrogenative–Dehydrogenative–Decarboxylative Coupling of β‐Ketoacids with Trifluorodiazoethane: Facile Access to Trifluoromethylated Aldol Products 下载免费PDF全文
Dr. Heng‐Ying Xiong Zhen‐Yan Yang Zhen Chen Jun‐Liang Zeng Dr. Jing Nie Prof. Jun‐An Ma 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(27):8325-8329
A novel copper‐catalyzed one‐pot cross‐coupling of β‐ketoacids with in situ generated trifluorodiazoethane has been developed. This reaction provides a direct and efficient method, in which one C?C bond and one C?O bond were formed in a carbenoid center with concomitant denitrogenation–dehydrogenation–decarboxylation, to afford trifluoromethylated aldol products. In several preliminary experiments, good to high enantioselectivities were also obtained. 相似文献
997.
红光发射稀土上转换发光纳米晶(UCNPs)在光动力治疗(PDT)等方面具有特定的优势。将油溶性的UCNPs通过表面改性转变为水溶性,对其在生物医疗、疾病诊断等方面的应用具有重要意义。利用一种简单易行的方法将具有红光发射的UCNPs进行介孔直接功能化表面修饰,制备了一种具有良好水溶性的纳米材料NaYF4:Yb/Er/Mn@mSiO2。实验结果表明该材料核-壳结构明显,形貌均一,在980 nm的激发下保持了上转换发光特性。该材料在光动力治疗等方面具有良好的潜在应用价值。 相似文献
998.
陕南茶叶稀土元素产地特征研究 总被引:1,自引:0,他引:1
为了掌握陕南茶叶中稀土元素含量和分布状况,并利用稀土元素对茶叶产地进行判别,采用ICP-MS法对陕南地区44个茶叶样品中16种稀土元素进行了测定。结果表明:茶叶中不同稀土元素含量差异较大,其中La,Ce,Nd含量较高,平均含量分别为124.81,172.13,87.20μg·kg-1;茶叶样品中稀土氧化物含量范围为200.32~1558.35μg·kg-1,总体上呈东高西低趋势,且均低于国家规定限量;茶叶中稀土元素随地域变化表现出不同分布特征,但具有相似的丰度模式;利用主成分分析将茶叶稀土元素归结为轻稀土组和重稀土组,间接地证明轻稀土元素和重稀土元素在从土壤到茶叶迁移过程中仍存在着差异;聚类分析结果表明,稀土元素可作为陕南茶叶产地判别的重要指标。 相似文献
999.
水杨羟肟酸对氟碳铈矿的捕收机制研究 总被引:2,自引:0,他引:2
以水杨羟肟酸为捕收剂,通过浮选试验、溶液化学计算、动电位和红外光谱检测分析研究了氟碳铈矿的可浮性及药剂与矿物的作用机制。当水杨羟肟酸浓度为5×10-4mol·L-1时,氟碳铈矿在pH=7~10较宽的范围内有较好的可浮性,与矿物表面的稀土阳离子的水解产物种类及其浓度有关。pH=8~9范围内,稀土阳离子水解优势组分RE(OH)2+和RE(OH)+2吸附在氟碳铈矿表面是主要的正活性质点,有利于药剂的化学吸附。在pH=8.3时,水杨羟肟酸对氟碳铈矿捕收是化学吸附作用生成五元环螯合物的结果。 相似文献
1000.
An Aluminophosphate Molecular Sieve with 36 Crystallographically Distinct Tetrahedral Sites 下载免费PDF全文
Jun Kyu Lee Alessandro Turrina Liangkui Zhu Seungwan Seo Dr. Daliang Zhang Dr. Paul A. Cox Prof. Paul A. Wright Prof. Shilun Qiu Prof. Suk Bong Hong 《Angewandte Chemie (International ed. in English)》2014,53(29):7480-7483
The structure of the new medium‐pore aluminophosphate molecular sieve PST‐6 is determined by the combined use of rotation electron diffraction tomography, synchrotron X‐ray powder diffraction, and computer modeling. PST‐6 was prepared by calcination of another new aluminophosphate material with an unknown structure synthesized using diethylamine as a structure‐directing agent, which is thought to contain bridging hydroxy groups. PST‐6 has 36 crystallographically distinct tetrahedral sites in the asymmetric unit and is thus crystallographically the most complex zeolitic structure ever solved. 相似文献