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941.
An asymmetric hydrogenation of aroylacrylic acids catalyzed by RuPHOX-Ru catalyst has been developed, affording the corresponding chiral γ-lactones in high yields and with up to 93% ee. The methodology has the advantage of utilizing easily accessible substrates and has therefore expand the scope of the resulting chiral γ-lactones. Furthermore, high catalytic efficiency was achieved in that the reduction of both the CC and CO double bonds was achieved in one step. The current work provides an alternative and convenient pathway for the synthesis of a wide range of chiral γ-lactones. 相似文献
942.
943.
Mykola Telychko Jie Su Aurelio Gallardo Yanwei Gu Jesús I. Mendieta‐Moreno Dongchen Qi Anton Tadich Shaotang Song Pin Lyu Zhizhan Qiu Hanyan Fang Ming Joo Koh Jishan Wu Pavel Jelínek Jiong Lu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(51):18764-18770
The ability to use mechanical strain to steer chemical reactions creates completely new opportunities for solution‐ and solid‐phase synthesis of functional molecules and materials. However, this strategy is not readily applied in the bottom‐up on‐surface synthesis of well‐defined nanostructures. We report an internal strain‐induced skeletal rearrangement of one‐dimensional (1D) metal–organic chains (MOCs) via a concurrent atom shift and bond cleavage on Cu(111) at room temperature. The process involves Cu‐catalyzed debromination of organic monomers to generate 1,5‐dimethylnaphthalene diradicals that coordinate to Cu adatoms, forming MOCs with both homochiral and heterochiral naphthalene backbone arrangements. Bond‐resolved non‐contact atomic force microscopy imaging combined with density functional theory calculations showed that the relief of substrate‐induced internal strain drives the skeletal rearrangement of MOCs via 1,3‐H shifts and shift of Cu adatoms that enable migration of the monomer backbone toward an energetically favorable registry with the Cu(111) substrate. Our findings on this strain‐induced structural rearrangement in 1D systems will enrich the toolbox for on‐surface synthesis of novel functional materials and quantum nanostructures. 相似文献
944.
Shao‐Dong Su Xiao‐Quan Zhu Yue‐Hong Wen Lin‐Tao Zhang Yu‐Ying Yang Chen‐Sheng Lin Xin‐Tao Wu Tian‐Lu Sheng 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(43):15488-15492
An unusual tetra‐nuclear linear cyanido‐bridged complex [Ru2(μ‐ap)4‐CN‐Ru2(μ‐ap)4](BPh4) ( 1 ) (ap=2‐anilinopyridinate) has been synthesized and well characterized. The crystallographic data, magnetic measurement, IR, EPR and theoretical calculation results demonstrate that complex 1 is the first example of mixed spin Ru25+‐based complex with uncommon electronic configurations of S=1/2 for the cyanido‐C bound Ru25+ and S=3/2 for the cyanido‐N bound Ru25+. This phenomenon can be understood by the theoretical calculation results that from the precursor Ru2(μ‐ap)4(CN) (S=3/2) to complex 1 the energy gap between π* and δ* orbitals of the cyanido‐C bound Ru25+ core increases from 0.57 to 1.61 eV due to the enhancement of asymmetrical π back‐bonding effect, but that of the cyanido‐N bound Ru25+ core is essential identical (0.56 eV). Besides, the analysis of UV/Vis‐NIR spectra suggests that there exists metal to metal charge transfer (MMCT) from the cyanido‐N bound Ru25+ (S=3/2) to the cyanido‐C bound Ru25+ (S=1/2), supported by the TDDFT calculations. 相似文献
945.
Hanxue Liang Qihua Liao Nan Chen Yuan Liang Guiqin Lv Panpan Zhang Bing Lu Liangti Qu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(52):19217-19222
Solar‐driven interfacial water evaporation yield is severely limited by the low efficiency of solar thermal energy. Herein, the injection control technique (ICT) achieves a capillary water state in rGO foam and effectively adjusts the water motion mode therein. Forming an appropriate amount of capillary water in the 3D graphene foam can greatly increase the vapor escape channel, by ensuring that the micrometer‐sized pore channels do not become completely blocked by water and by exposing as much evaporation area as possible while preventing solar heat from being used to heat excess water. The rate of solar steam generation can reach up to 2.40 kg m?2 h?1 under solar illumination of 1 kW m?2, among the best values reported. In addition, solar thermal efficiency approaching 100 % is achieved. This work enhances solar water‐evaporation performance and promotes the application of solar‐driven evaporation systems made of carbon‐based materials. 相似文献
946.
947.
Bin Li Bin Wang Xiayang Huang Lu Dai Lei Cui Jian Li Xueshun Jia Chunju Li 《Angewandte Chemie (International ed. in English)》2019,58(12):3885-3889
Herein, two new classes of macrocyclic compounds, terphen[n]arenes (TPns) (n=3–6) and quaterphen[n]arenes (QPns) (n=3–6), were designed and synthesized by a one‐step condensation reaction in relatively high yields. They comprise 2,2′′‐dimethoxy terphenyl and 2,2′′′‐dimethoxy quaterphenyl monomers, respectively, linked by methylene bridges. Given their long and rigid monomers, TPns and QPns have much larger cavities and better self‐assembly properties than classic macrocycles. More interestingly, the cyclic pentamers and hexamers TP5, TP6, QP5, and QP6 formed supramolecular organogels, which were composed of interwoven fibers, nanosheets, or entangled macropore networks formed by multiple face‐to‐face and edge‐to‐face π???π stacking interactions. The xerogel materials effectively captured volatile iodine, not only in aqueous media but also in the gaseous state, and could be recycled multiple times without obvious loss in performance. 相似文献
948.
949.
Lu Xiao Chunmei Gu Yu Xiang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(40):14305-14310
RNA‐cleaving DNAzymes are useful tools for intracellular metal‐ion sensing and gene regulation. Incorporating stimuli‐responsive modifications into these DNAzymes enables their activities to be spatiotemporally and chemically controlled for more precise applications. Despite the successful development of many caged DNAzymes for light‐induced activation, DNAzymes that can be intracellularly activated by chemical inputs of biological importance, such as reactive oxygen species (ROS), are still scarce. ROS like hydrogen peroxide (H2O2) and hypochlorite (HClO) are critical mediators of oxidative stress‐related cell signaling and dysregulation including activation of immune system as well as progression of diseases and aging. Herein, we report ROS‐activable DNAzymes by introducing phenylboronate and phosphorothioate modifications to the Zn2+‐dependent 8–17 DNAzyme. These ROS‐activable DNAzymes were orthogonally activated by H2O2 and HClO inside live human and mouse cells. 相似文献
950.
Zhiyu Lin Yang Yang Mengsi Li Hao Huang Wei Hu Ling Cheng Wensheng Yan Zhiwu Yu Kaitian Mao Guoliang Xia Jian Lu Peng Jiang Kang Yang Ruirui Zhang Pengping Xu Changlai Wang Lin Hu Qianwang Chen 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(47):17129-17136
Graphene‐based materials still exhibit poor electrocatalytic activities for the hydrogen evolution reaction (HER) although they are considered to be the most promising electrocatalysts. We fabricated a graphene‐analogous material displaying exceptional activity towards the HER under acidic conditions with an overpotential (57 mV at 10 mA cm?2) and Tafel slope (44.6 mV dec?1) superior to previously reported graphene‐based materials, and even comparable to the state‐of‐the art Pt/C catalyst. X‐ray absorption near‐edge structure (XANES) and solid‐state NMR studies reveal that the distinct feature of its structure is dual graphitic‐N doping in a six‐membered carbon ring. Density functional theory (DFT) calculations show that the unique doped structure is beneficial for the activation of C?H bonds and to make the carbon atom bonded to two graphitic N atoms an active site for the HER. 相似文献