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971.
The Hydrogen Evolution Reaction in Alkaline Solution: From Theory,Single Crystal Models,to Practical Electrocatalysts 下载免费PDF全文
Dr. Yao Zheng Dr. Yan Jiao Anthony Vasileff Prof. Shi‐Zhang Qiao 《Angewandte Chemie (International ed. in English)》2018,57(26):7568-7579
The hydrogen evolution reaction (HER) is a fundamental process in electrocatalysis and plays an important role in energy conversion for the development of hydrogen‐based energy sources. However, the considerably slow rate of the HER in alkaline conditions has hindered advances in water splitting techniques for high‐purity hydrogen production. Differing from well documented acidic HER, the mechanistic aspects of alkaline HER are yet to be settled. A critical appraisal of alkaline HER electrocatalysis is presented, with a special emphasis on the connection between fundamental surface electrochemistry on single‐crystal models and the derived molecular design principle for real‐world electrocatalysts. By presenting some typical examples across theoretical calculations, surface characterization, and electrochemical experiments, we try to address some key ongoing debates to deliver a better understanding of alkaline HER at the atomic level. 相似文献
972.
Diverged Plant Terpene Synthases Reroute the Carbocation Cyclization Path towards the Formation of Unprecedented 6/11/5 and 6/6/7/5 Sesterterpene Scaffolds 下载免费PDF全文
Dr. Ancheng C. Huang Dr. Young J. Hong Dr. Andrew D. Bond Prof. Dr. Dean J. Tantillo Prof. Anne Osbourn 《Angewandte Chemie (International ed. in English)》2018,57(5):1291-1295
Sesterterpenoids are a relatively rare class of plant terpenes. Sesterterpene synthase (STS)‐mediated cyclization of the linear C25 isoprenoid precursor geranylfarnesyl diphosphate (GFPP) defines sesterterpene scaffolds. So far only a very limited number of STSs have been characterized. The discovery of three new plant STSs is reported that produce a suite of sesterterpenes with unprecedented 6/11/5 and 6/6/7/5 fused ring systems when transiently co‐expressed with a GFPP synthase in Nicotiana benthamiana. Structural elucidation, feeding experiments, and quantum chemical calculations suggest that these STSs catalyze an unusual cyclization path involving reprotonation, intramolecular 1,6 proton transfer, and concerted but asynchronous bicyclization events. The cyclization is diverted from those catalyzed by the characterized plant STSs by forming unified 15/5 bicyclic sesterterpene intermediates. Mutagenesis further revealed a conserved amino acid residue implicated in reprotonation. 相似文献
973.
Ana Sánchez‐Iglesias Nathalie Claes Dr. Diego M. Solís Dr. Jose M. Taboada Prof. Sara Bals Prof. Luis M. Liz‐Marzán Dr. Marek Grzelczak 《Angewandte Chemie (International ed. in English)》2018,57(12):3183-3186
A limiting factor of solvent‐induced nanoparticle self‐assembly is the need for constant sample dilution in assembly/disassembly cycles. Changes in the nanoparticle concentration alter the kinetics of the subsequent assembly process, limiting optical signal recovery. Herein, we show that upon confining hydrophobic nanoparticles in permeable silica nanocapsules, the number of nanoparticles participating in cyclic aggregation remains constant despite bulk changes in solution, leading to highly reproducible plasmon band shifts at different solvent compositions. 相似文献
974.
Helicenophyrins: Expanded Carbaporphyrins Incorporating Aza[5]helicene and Heptacyclic S‐Shaped Aza[5]helicene Motifs 下载免费PDF全文
Dr. Bartosz Szyszko Monika Przewoźnik Dr. Michał J. Białek Dr. Agata Białońska Prof. Dr. Piotr J. Chmielewski Dr. Jakub Cichos Prof. Dr. Lechosław Latos‐Grażyński 《Angewandte Chemie (International ed. in English)》2018,57(15):4030-4034
Incorporation of phenanthrene into a hexaphyrin(1.1.1.1.1.0) frame resulted in intramolecular ring fusion, thus giving rise to chiral helicenophyrins. These molecules contain helicene and porphyrin features by incorporating either an aza[5]helicene or heptacyclic S‐shaped aza[5]helicene. 相似文献
975.
Eosin Y as a Direct Hydrogen‐Atom Transfer Photocatalyst for the Functionalization of C−H Bonds 下载免费PDF全文
Xuan‐Zi Fan Dr. Jia‐Wei Rong Hao‐Lin Wu Quan Zhou Dr. Hong‐Ping Deng Jin Da Tan Cheng‐Wen Xue Dr. Li‐Zhu Wu Dr. Hai‐Rong Tao Dr. Jie Wu 《Angewandte Chemie (International ed. in English)》2018,57(28):8514-8518
Eosin Y, a well‐known economical alternative to metal catalysts in visible‐light‐driven single‐electron transfer‐based organic transformations, can behave as an effective direct hydrogen‐atom transfer catalyst for C?H activation. Using the alkylation of C?H bonds with electron‐deficient alkenes as a model study revealed an extremely broad substrate scope, enabling easy access to a variety of important synthons. This eosin Y‐based photocatalytic hydrogen‐atom transfer strategy is promising for diverse functionalization of a wide range of native C?H bonds in a green and sustainable manner. 相似文献
976.
Monochalcoplatin: An Actively Transported,Quickly Reducible,and Highly Potent PtIV Anticancer Prodrug 下载免费PDF全文
Dr. Lili Ma Na Wang Rong Ma Cai Li Zoufeng Xu Dr. Man‐Kit Tse Prof. Dr. Guangyu Zhu 《Angewandte Chemie (International ed. in English)》2018,57(29):9098-9102
Recently, PtIV prodrugs have attracted much attention as the next generation of platinum‐based antineoplastic drug candidates. Here we report the discovery and evaluation of monochalcoplatin, a monocarboxylated PtIV prodrug that is among the most cytotoxic PtIV prodrugs to date. Compared with its dicarboxylated counterpart chalcoplatin, monochalcoplatin accumulates astonishingly effectively and rapidly in cancer cells, which is not ascribed to its lipophilicity. The prodrug is quickly reduced, causes DNA damage, and induces apoptosis, resulting in superior cytotoxicity with IC50 values in the nanomolar range in both cisplatin‐sensitive and ‐resistant cells; these IC50 values are up to 422‐fold higher than that of cisplatin. A detailed mechanistic study reveals that monochalcoplatin actively enters cells through a transporter‐mediated process. Moreover, monochalcoplatin shows significant antitumor activity in an in vivo colorectal tumor model. Our study implies a practical strategy for the design of more effective PtIV prodrugs to conquer drug resistance by tuning both cellular uptake pathways and activation processes. 相似文献
977.
Experimental Evidence for a Triboluminescent Antiperovskite Ferroelectric: Tris(trimethylammonium) catena‐Tri‐μ‐chloro‐manganate(II) Tetrachloromanganate(II) 下载免费PDF全文
Dr. Peng‐Fei Li Dr. Yuan‐Yuan Tang Dr. Wei‐Qiang Liao Dr. Ping‐Ping Shi Dr. Xiu‐Ni Hua Dr. Yi Zhang Dr. Zhenhong Wei Dr. Hu Cai Prof. Ren‐Gen Xiong 《Angewandte Chemie (International ed. in English)》2018,57(37):11939-11942
The perovskite structure is rich in ferroelectricity. In contrast, ferroelectric antiperovskites have been scarcely confirmed experimentally since the discovery of M3AB‐type antiperovskites in the 1930s. Ferroelectricity is now revealed in an organic–inorganic hybrid X3AB antiperovskite structure, which exhibits a clear ferroelectric phase transition 6/mmmF6mm with a high Curie point of 480 K. The physical properties across the phase transition are obviously changed along with the symmetry requirements, providing solid experimental evidence for the ferroelectric phase transition. More interestingly, the discovered antiperovskite shows intense photoluminescence and triboluminescence properties. The confirmation of the triboluminescent ferroelectric antiperovskite will open new avenues to explore excellent optoelectronic properties in the antiperovskite family. 相似文献
978.
The β‐Agostic Structure in (C5Me5)2Sc(CH2CH3): Solid‐State NMR Studies of (C5Me5)2Sc−R (R=Me,Ph, Et) 下载免费PDF全文
Damien B. Culver Winn Huynh Dr. Hosein Tafazolian Dr. Ta‐Chung Ong Prof. Dr. Matthew P. Conley 《Angewandte Chemie (International ed. in English)》2018,57(30):9520-9523
Multinuclear solid‐state NMR studies of Cp*2Sc?R (Cp*=pentamethylcyclopentadienyl; R=Me, Ph, Et) and DFT calculations show that the Sc?Et complex contains a β‐CH agostic interaction. The static central transition 45Sc NMR spectra show that the quadrupolar coupling constants (Cq) follow the trend of Ph≈Me>Et, indicating that the Sc?R bond is different in Cp*2Sc?Et compared to the methyl and phenyl complexes. Analysis of the chemical shift tensor (CST) shows that the deshielding experienced by Cβ in Sc?CH2CH3 is related to coupling between the filled σC‐C orbital and the vacant orbital. 相似文献
979.
Stress‐Transfer‐Induced In Situ Formation of Ultrathin Nickel Phosphide Nanosheets for Efficient Hydrogen Evolution 下载免费PDF全文
Shao‐Hai Li Dr. Nan Zhang Dr. Xiuqiang Xie Prof. Dr. Rafael Luque Prof. Dr. Yi‐Jun Xu 《Angewandte Chemie (International ed. in English)》2018,57(40):13082-13085
Ultrathin two‐dimensional (2D) nanostructures have attracted increasing research interest for energy storage and conversion. However, tackling the key problem of lattice mismatch inducing the instability of ulreathin nanostructures during phase transformations is still a critical challenge. Herein, we describe a facile and scalable strategy for the growth of ultrathin nickel phosphide (Ni2P) nanosheets (NSs) with exposed (001) facets. We show that single‐layer functionalized graphene with residual oxygen‐containing groups and a large lateral size contributes to reducing the lattice strain during phosphorization. The resulting nanostructure exhibits remarkable hydrogen evolution activity and good stability under alkaline conditions. 相似文献
980.
Vanessa A. Béland Zhiqiang Wang Prof. Tsun‐Kong Sham Prof. Paul J. Ragogna 《Angewandte Chemie (International ed. in English)》2018,57(40):13252-13256
The synthesis of phosphane‐ene photopolymer networks, where the networks are composed of crosslinked tertiary alkyl phosphines are reported. Taking advantage of the rich coordination chemistry of alkyl phosphines, stibino‐phosphonium and stibino‐bis(phosphonium) functionalized polymer networks could be generated. Small‐molecule stibino‐phosphonium and stibino‐bis(phosphonium) compounds have been well characterized previously and were used as models for spectroscopic comparison to the macromolecular analogues by NMR and XANES spectroscopy. This work reveals that the physical and electronic properties of the materials can be tuned depending on the type of coordination environment. These materials can be used as ceramic precursors, where the Sb‐functionalized polymers influence the composition of the resulting ceramic. 相似文献