共查询到20条相似文献,搜索用时 15 毫秒
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Hang Xu Chun‐Shuai Cao Han‐Shi Hu Shi‐Bin Wang Jin‐Cheng Liu Peng Cheng Nikolas Kaltsoyannis Jun Li Bin Zhao 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(18):6083-6088
Assembled from [Th48Ni6] nanocages, the first transition‐metal (TM)‐thorium metal–organic framework (MOF, 1 ) has been synthesized and structurally characterized. 1 exhibits high solvent and acid/base stability, and resistance to 400 kGy β irradiation. Notably, 1 captures ReO4? (an analogue of radioactive 99TcO4?, a key species in nuclear wastes) with a maximum capacity of 807 mg g?1, falling among the largest values known to date. Furthermore, 1 can enrich methylene blue (MB) and can also serve as an effective and recyclable catalyst for CO2 fixation with epoxides; there is no significant loss of catalytic activity after 10 cycles. Theoretical studies with nucleus‐independent chemical shifts and natural bond orbital analysis reveal that the [Th6O8] clusters in 1 have a unique stable electronic structure with (d–p)π aromaticity, partially rationalising 1 ′s stability. 相似文献
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Sibo Wang Wangshu Yao Jinliang Lin Zhengxin Ding Xinchen Wang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(4):1052-1056
Metal–organic frameworks (MOFs) have shown great promise for CO2 capture and storage. However, the operation of chemical redox functions of framework substances and organic CO2‐trapping entities which are spatially linked together to catalyze CO2 conversion has had much less attention. Reported herein is a cobalt‐containing zeolitic imidazolate framework (Co‐ZIF‐9) which serves as a robust MOF cocatalyst to reduce CO2 by cooperating with a ruthenium‐based photosensitizer. The catalytic turnover number of Co‐ZIF‐9 was about 450 within 2.5 hours under mild reaction conditions, while still keeping its original reactivity during prolonged operation. 相似文献
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Xu Zhang Jiao Sun Guangfeng Wei Zhipan Liu Huimin Yang Kaimin Wang Honghan Fei 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(9):2870-2875
The reported metal–organic framework (MOF) catalyst realizes CO2 to methanol transformation under ambient conditions. The MOF is one rare example containing metal‐free N‐heterocyclic carbene (NHC) moieties, which are installed using an in situ generation strategy involving the incorporation of an imidazolium bromide based linker into the MOF by postsynthetic ligand exchange. Importantly, the resultant NHC‐functionalized MOF is the first catalyst capable of performing quantitative hydrogen transfer from silanes to CO2, thus achieving quantitative (>99 %) methanol yield. Density‐functional theory calculations indicate the high catalytic activity of the NHC sites in MOFs are attributed to the decreased reaction barrier of a reaction route involving the formation of an NHC‐silane adduct. In addition, the MOF‐immobilized NHC catalyst shows enhanced stability for up to eight cycles without base activation, as well as high selectivity towards the desired silyl methoxide product. 相似文献
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Li‐Yuan Wu Yan‐Fei Mu Xiao‐Xuan Guo Wen Zhang Zhi‐Ming Zhang Min Zhang Tong‐Bu Lu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(28):9591-9595
Improving the stability of lead halide perovskite quantum dots (QDs) in a system containing water is the key for their practical application in artificial photosynthesis. Herein, we encapsulate low‐cost CH3NH3PbI3 (MAPbI3) perovskite QDs in the pores of earth‐abundant Fe‐porphyrin based metal organic framework (MOF) PCN‐221(Fex) by a sequential deposition route, to construct a series of composite photocatalysts of MAPbI3@PCN‐221(Fex) (x=0–1). Protected by the MOF the composite photocatalysts exhibit much improved stability in reaction systems containing water. The close contact of QDs to the Fe catalytic site in the MOF, allows the photogenerated electrons in the QDs to transfer rapidly the Fe catalytic sites to enhance the photocatalytic activity for CO2 reduction. Using water as an electron source, MAPbI3@PCN‐221(Fe0.2) exhibits a record‐high total yield of 1559 μmol g?1 for photocatalytic CO2 reduction to CO (34 %) and CH4 (66 %), 38 times higher than that of PCN‐221(Fe0.2) in the absence of perovskite QDs. 相似文献
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Anastasia Terzopoulou Marcus Hoop Xiang‐Zhong Chen Ann M. Hirt Michalis Charilaou Yang Shen Fajer Mushtaq Angel Prez delPino Constantin Logofatu Laura Simonelli Andrew J. de Mello Christian J. Doonan Jordi Sort Bradley J. Nelson Salvador Pan Josep Puigmartí‐Luis 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(38):13684-13689
Metal–organic frameworks (MOFs) capable of mobility and manipulation are attractive materials for potential applications in targeted drug delivery, catalysis, and small‐scale machines. One way of rendering MOFs navigable is incorporating magnetically responsive nanostructures, which usually involve at least two preparation steps: the growth of the magnetic nanomaterial and its incorporation during the synthesis of the MOF crystals. Now, by using optimal combinations of salts and ligands, zeolitic imidazolate framework composite structures with ferrimagnetic behavior can be readily obtained via a one‐step synthetic procedure, that is, without the incorporation of extrinsic magnetic components. The ferrimagnetism of the composite originates from binary oxides of iron and transition metals such as cobalt. This approach exhibits similarities to the natural mineralization of iron oxide species, as is observed in ores and in biomineralization. 相似文献
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Rational Design of Crystalline Covalent Organic Frameworks for Efficient CO2 Photoreduction with H2O
Meng Lu Jiang Liu Qiang Li Mi Zhang Ming Liu Jin‐Lan Wang Da‐Qiang Yuan Ya‐Qian Lan 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(36):12522-12527
Solar energy‐driven conversion of CO2 into fuels with H2O as a sacrificial agent is a challenging research field in photosynthesis. Herein, a series of crystalline porphyrin‐tetrathiafulvalene covalent organic frameworks (COFs) are synthesized and used as photocatalysts for reducing CO2 with H2O, in the absence of additional photosensitizer, sacrificial agents, and noble metal co‐catalysts. The effective photogenerated electrons transfer from tetrathiafulvalene to porphyrin by covalent bonding, resulting in the separated electrons and holes, respectively, for CO2 reduction and H2O oxidation. By adjusting the band structures of TTCOFs, TTCOF‐Zn achieved the highest photocatalytic CO production of 12.33 μmol with circa 100 % selectivity, along with H2O oxidation to O2. Furthermore, DFT calculations combined with a crystal structure model confirmed the structure–function relationship. Our work provides a new sight for designing more efficient artificial crystalline photocatalysts. 相似文献
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Shuo Dou Jiajia Song Shibo Xi Yonghua Du Jiong Wang Zhen‐Feng Huang Zhichuan J. Xu Xin Wang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(12):4081-4085
Electrochemical CO2 reduction relies on the availability of highly efficient and selective catalysts. Herein, we report a general strategy to boost the activity of metal–organic frameworks (MOFs) towards CO2 reduction via ligand doping. A strong electron‐donating molecule of 1,10‐phenanthroline was doped into Zn‐based MOFs of zeolitic imidazolate framework‐8 (ZIF‐8) as CO2 reduction electrocatalyst. Experimental and theoretical evidences reveal that the electron‐donating nature of phenanthroline enables a charge transfer, which induces adjacent active sites at the sp2 C atoms in the imidazole ligand possessing more electrons, and facilitates the generation of *COOH, hence leading to improved activity and Faradaic efficiency towards CO production. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(17):4845-4849
A crack‐free sub‐nanometer composite structure for the study of ion transfer was constructed by in situ growth of ZIF‐90 [Zn(ICA)2, ICA=Imidazole‐2‐carboxaldehyde] on the tip of a glass nanopipette. The potential‐driven ion transfer through the sub‐nanometer channels in ZIF‐90 is strongly influenced by the pH of the solution. A rectification ratio over 500 is observed in 1 m KCl solution under alkaline conditions (pH 11.58), which is the highest value reported under such a high salt concentration. Fluorescence experiments show the super‐high rectification ratio under alkaline conditions results from the strong electrostatic interaction between ions and the sub‐nanometer channels of ZIF‐90. In addition to providing a general pathway for further study of mass‐transfer process through sub‐nanometer channels, the approach enable all kinds of metal–organic frameworks (MOFs) to be used as ionic permselectivity materials in nanopore‐based analysis. 相似文献
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Yun‐Lei Peng Chaohui He Tony Pham Ting Wang Pengfei Li Rajamani Krishna Katherine A. Forrest Adam Hogan Shanelle Suepaul Brian Space Ming Fang Yao Chen Michael J. Zaworotko Jinping Li Libo Li Zhenjie Zhang Peng Cheng Banglin Chen 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(30):10315-10320
Simultaneous removal of trace amounts of propyne and propadiene from propylene is an important but challenging industrial process. We report herein a class of microporous metal–organic frameworks ( NKMOF‐1‐M ) with exceptional water stability and remarkably high uptakes for both propyne and propadiene at low pressures. NKMOF‐1‐M separated a ternary propyne/propadiene/propylene (0.5 : 0.5 : 99.0) mixture with the highest reported selectivity for the production of polymer‐grade propylene (99.996 %) at ambient temperature, as attributed to its strong binding affinity for propyne and propadiene over propylene. Moreover, we were able to visualize propyne and propadiene molecules in the single‐crystal structure of NKMOF‐1‐M through a convenient approach under ambient conditions, which helped to precisely understand the binding sites and affinity for propyne and propadiene. These results provide important guidance on using ultramicroporous MOFs as physisorbent materials. 相似文献
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Daopeng Sheng Lin Zhu Xing Dai Chao Xu Peng Li Carolyn I. Pearce Chengliang Xiao Jing Chen Ruhong Zhou Tao Duan Omar K. Farha Zhifang Chai Shuao Wang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(15):5022-5026
99Tc contamination at legacy nuclear sites is a serious and unsolved environmental issue. The selective remediation of 99TcO4? in the presence of a large excess of NO3? and SO42? from natural waste systems represents a significant scientific and technical challenge, since anions with a higher charge density are often preferentially sorbed by traditional anion‐exchange materials. We present a solution to this challenge based on a stable cationic metal‐organic framework, SCU‐102 (Ni2(tipm)3(NO3)4), which exhibits fast sorption kinetics, a large capacity (291 mg g?1), a high distribution coefficient, and, most importantly, a record‐high TcO4? uptake selectivity. This material can almost quantitatively remove TcO4? in the presence of a large excess of NO3? and SO42?. Decontamination experiments confirm that SCU‐102 represents the optimal Tc scavenger with the highest reported clean‐up efficiency, while first‐principle simulations reveal that the origin of the selectivity is the recognition of TcO4? by the hydrophobic pockets of the structure. 相似文献
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Bin Zheng Guillaume Maurin 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(39):13872-13876
One intriguing feature of many porous MOFs is their stimulus‐induced flexibility, which makes them unique compared to standard adsorbents. Here we propose an innovative concept to achieve an efficient kinetic separation of species with similar properties by the mechanical fine‐tuning of the pore architecture of the flexible zeolitic imidazolate framework ZIF‐8. This unprecedented approach was applied to one of the most challenging societally relevant separations: the separation of propylene and propane, which is of vital importance in the petrochemical industry. It was demonstrated that the application of an external pressure creates a gradual enhancement in the propylene/propane diffusion selectivity to more than one order of magnitude at 1 GPa pressure. A detailed analysis of the molecular simulations was further able to unravel the origin of this unusual behavior at the atomistic level. 相似文献
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Dr. Fan Yang Wenhui Hu Dr. Chongqing Yang Margaret Patrick Prof. Andrew L. Cooksy Dr. Jian Zhang Dr. Jeffery A. Aguiar Dr. Chengcheng Fang Prof. Yinghua Zhou Prof. Ying Shirley Meng Prof. Jier Huang Prof. Jing Gu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(11):4602-4610
A gas-phase approach to form Zn coordination sites on metal–organic frameworks (MOFs) by vapor-phase infiltration (VPI) was developed. Compared to Zn sites synthesized by the solution-phase method, VPI samples revealed approximately 2.8 % internal strain. Faradaic efficiency towards conversion of CO2 to CO was enhanced by up to a factor of four, and the initial potential was positively shifted by 200–300 mV. Using element-specific X-ray absorption spectroscopy, the local coordination environment of the Zn center was determined to have square-pyramidal geometry with four Zn−N bonds in the equatorial plane and one Zn-OH2 bond in the axial plane. The fine-tuned internal strain was further supported by monitoring changes in XRD and UV/Visible absorption spectra across a range of infiltration cycles. The ability to use internal strain to increase catalytic activity of MOFs suggests that applying this strategy will enhance intrinsic catalytic capabilities of a variety of porous materials. 相似文献
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Ning Li Jiang Liu Jing‐Jing Liu Long‐Zhang Dong Zhi‐Feng Xin Yun‐Lei Teng Ya‐Qian Lan 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(16):5280-5285
Visible‐light driven photoconversion of CO2 into energy carriers is highly important to the natural carbon balance and sustainable development. Demonstrated here is the adenine‐dependent CO2 photoreduction performance in green biomimetic metal–organic frameworks. Photocatalytic results indicate that AD‐MOF‐2 exhibited a very high HCOOH production rate of 443.2 μmol g?1 h?1 in pure aqueous solution, and is more than two times higher than that of AD‐MOF‐1 (179.0 μmol g?1h?1) in acetonitrile solution. Significantly, experimental and theoretical evidence reveal that the CO2 photoreduction reaction mainly takes place at the aromatic nitrogen atom of adenine molecules through a unique o‐amino‐assisted activation rather than at the metal center. This work not only serves as an important case study for the development of green biomimetic photocatalysts used for artificial photosynthesis, but also proposes a new catalytic strategy for efficient CO2 photoconversion. 相似文献