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991.
Wence Xu Guilan Fan Jialiang Chen Jinhan Li Le Zhang Shengli Zhu Xuncheng Su Fangyi Cheng Jun Chen 《Angewandte Chemie (International ed. in English)》2020,59(9):3511-3516
The electrocatalytic nitrogen reduction reaction (NRR) is an alternative eco‐friendly strategy for sustainable N2 fixation with renewable energy. However, NRR suffers from sluggish kinetics owing to difficult N2 adsorption and N≡N cleavage. Now, nanoporous palladium hydride is reported as electrocatalyst for electrochemical N2 reduction under ambient conditions, achieving a high ammonia yield rate of 20.4 μg h?1 mg?1 with a Faradaic efficiency of 43.6 % at low overpotential of 150 mV. Isotopic hydrogen labeling studies suggest the involvement of lattice hydrogen atoms in the hydride as active hydrogen source. In situ Raman analysis and density functional theory (DFT) calculations further reveal the reduction of energy barrier for the rate‐limiting *N2H formation step. The unique protonation mode of palladium hydride would provide a new insight on designing efficient and robust electrocatalysts for nitrogen fixation. 相似文献
992.
Chao Liu Jing Wang Jingjing Wan Yan Cheng Rong Huang Chaoqi Zhang Wenli Hu Guangfeng Wei Chengzhong Yu 《Angewandte Chemie (International ed. in English)》2020,59(9):3630-3637
Amorphous metal–organic frameworks (aMOFs) are an emerging family of attractive materials with great application potential, however aMOFs are usually prepared under harsh conditions and aMOFs with complex compositions and structures are rarely reported. In this work, an aMOF‐dominated nanocomposite (aMOF‐NC) with both structural and compositional complexity has been synthesized using a facile approach. A ligand‐competition amorphization mechanism is proposed based on experimental and density functional theory calculation results. The aMOF‐NC possesses a core–shell nanorod@nanosheet architecture, including a Fe‐rich Fe‐Co‐aMOF core and a Co‐rich Fe‐Co‐aMOF shell in the core–shell structured nanorod, and amorphous Co(OH)2 nanosheets as the outer layer. Benefiting from the structural and compositional heterogeneity, the aMOF‐NC demonstrates an excellent oxygen evolution reaction activity with a low overpotential of 249 mV at 10.0 mA cm?2 and Tafel slope of 39.5 mV dec?1. 相似文献
993.
Jianhua Zou Jianwei Zhu Zhen Yang Ling Li Wenpei Fan Liangcan He Wei Tang Liming Deng Jing Mu Yuanyuan Ma Yaya Cheng Wei Huang Xiaochen Dong Xiaoyuan Chen 《Angewandte Chemie (International ed. in English)》2020,59(23):8833-8838
Continuous irradiation during photodynamic therapy (PDT) inevitably induces tumor hypoxia, thereby weakening the PDT effect. In PDT‐induced hypoxia, providing singlet oxygen from stored chemical energy may enhance the cell‐killing effect and boost the therapeutic effect. Herein, we present a phototheranostic (DPPTPE@PEG‐Py NPs) prepared by using a 2‐pyridone‐based diblock polymer (PEG‐Py) to encapsulate a semiconducting, heavy‐atom‐free pyrrolopyrrolidone‐tetraphenylethylene (DPPTPE) with high singlet‐oxygen‐generation ability both in dichloromethane and water. The PEG‐Py can trap the 1O2 generated from DPPTPE under laser irradiation and form a stable intermediate of endoperoxide, which can then release 1O2 in the dark, hypoxic tumor microenvironment. Furthermore, fluorescence‐imaging‐guided phototherapy demonstrates that this phototheranostic could completely inhibit tumor growth with the help of laser irradiation. 相似文献
994.
Lanfang Ren Jia Lv Hui Wang Yiyun Cheng 《Angewandte Chemie (International ed. in English)》2020,59(12):4711-4719
Cytosolic protein delivery is a prerequisite for the development of protein therapeutics that act on intracellular targets. Proteins are generally membrane‐impermeable and thus need a carrier such as a polymer to facilitate their internalization. However, the efficient binding of proteins with different isoelectric points to polymeric carriers is challenging. In this study, we designed a coordinative dendrimer to solve this problem. The dendrimers modified with dipicolylamine/zinc(II) complex were capable of binding proteins through a combination of ionic and coordination interactions. The best polymer efficiently delivered 30 cargo proteins and peptides into the cytosol, while maintaining their bioactivity after intracellular release. The removal or replacement of zinc ions in the polymer with other transition‐metal ions lead to significantly decreased efficiency in cytosolic protein delivery. This study provides a new strategy to develop robust and efficient polymers for cytosolic protein delivery. 相似文献
995.
Xu Liu Ruoyu Liu Jiaxing Qiu Xu Cheng Guigen Li 《Angewandte Chemie (International ed. in English)》2020,59(33):13962-13967
We report a method for the electrochemical deuteration of α,β‐unsaturated carbonyl compounds under catalyst‐ and external‐reductant‐free conditions, with deuteration rates as high as 99 % and yields up to 91 % in 2 h. The use of graphite felt for both the cathode and the anode was key to ensuring chemoselectivity and high deuterium incorporation under neutral conditions without the need for an external reductant. This method has a number of advantages over previously reported deuteration reactions that use stoichiometric metallic reductants. Mechanistic experiments showed that O2 evolution at the anode not only eliminates the need for an external reductant but also regulates the pH of the reaction mixture, keeping it approximately neutral. 相似文献
996.
Fei Cheng Zhen-Xing Zou Ping-Sheng Xu Shui-Han Zhang Yan Zhang Cai-Ping Yao 《Natural product research》2020,34(9):1264-1269
AbstractThree new neolignan derivatives (1–3), together with three known isolariciresinol derivatives (4–6) were isolated from Selaginella picta. Their structures were elucidated by spectroscopic methods (1D/2D NMR, HRESIMS and CD). All isolated compounds were assayed on the neuroprotective activity against the injury of HT-22 cells induced by L-Glutamate in vitro. All compounds displayed potent protective effect on HT-22 cells. 相似文献
997.
Hang Kuen Lau Shruti Rattan Hongbo Fu Cristobal G. Garcia Dylan M. Barber Kristi L. Kiick Alfred J. Crosby 《Macromolecular bioscience》2020,20(5)
Local, micromechanical environment is known to influence cellular function in heterogeneous hydrogels, and knowledge gained in micromechanics will facilitate the improved design of biomaterials for tissue regeneration. In this study, a system comprising microstructured resilin‐like polypeptide (RLP)–poly(ethylene glycol) (PEG) hydrogels is utilized. The micromechanical properties of RLP‐PEG hydrogels are evaluated with oscillatory shear rheometry, compression dynamic mechanic analysis, small‐strain microindentation, and large‐strain indentation and puncture over a range of different deformation length scales. The measured elastic moduli are consistent with volume averaging models, indicating that volume fraction, not domain size, plays a dominant role in determining the low strain mechanical response. Large‐strain indentation under a confocal microscope enables the visualization of the microstructured hydrogel micromechanical deformation, emphasizing the translation, rotation, and deformation of RLP‐rich domains. The fracture initiation energy results demonstrate that failure of the composite hydrogels is controlled by the RLP‐rich phase, and their independence with domain size suggested that failure initiation is controlled by multiple domains within the strained volume. This approach and findings provide new quantitative insight into the micromechanical response of soft hydrogel composites and highlight the opportunities in employing these methods to understand the physical origins of mechanical properties of soft synthetic and biological materials. 相似文献
998.
Dongmei Zhang Bulei Wang Yajuan Sun Changhao Wang Somnath Mukherjee Cheng Yang Yashao Chen 《Macromolecular bioscience》2020,20(6)
Burn wound healing remains a challenging health problem worldwide due to the lack of efficient and precise therapy. Inherent oxidative stress following burn injury is importantly responsible for prolonged inflammation, fibrotic scar, and multiple organ failure. Herein, a bioinspired antioxidative defense system coupling with in situ forming hydrogel, namely, multiresponsive injectable catechol‐Fe3+ coordination hydrogel (MICH) matrix, is engineered to promote burn‐wound dermal repair by inhibiting tissue oxidative stress. This MICH matrix serves as the special traits of “Fe‐superoxide dismutases,” small molecular antioxidant (vitamin E), and extracellular matrix (ECM) in alleviating cellular oxidative damage, which demonstrates precise scavenging on reactive oxygen species (ROS) of different cellular locations, blocking lipid peroxidation and cell apoptosis. In in vivo burn‐wound treatment, this MICH promptly integrates with injured surrounding tissue to provide hydration microenvironment and physicochemical ECM for burn wounds. Importantly, the MICH matrix suppresses tissue ROS production, reducing the inflammatory response, prompting re‐epithelization and neoangiogenesis during wound healing. Meanwhile, the remodeling skin treated with MICH matrix demonstrates low collagen deposition and normal dermal collagen architecture. Overall, the MICH prevents burn wound progression and enhances skin regeneration, which might be a promising biomaterial for burn‐wound care and other disease therapy induced by oxidative stress. 相似文献
999.
Electronic Stability of Bimetallic Au2@Cu6 Nanocluster: Closed-Shell Interaction and Multicenter Bonding 下载免费PDF全文
Metallophilic interaction is a unique type of weak intermolecular interaction, where the electronic configuration of two metal atoms is closed shell. Despite its significance in multidisciplinary fields, the nature of metallophilic interaction is still not well understood. In this work, we investigated the electronic structures and bonding characteristic of bimetallic Au\begin{document}$ _{2} $\end{document} @Cu\begin{document}$ _{6} $\end{document} nanocluster through density functional theory method, which was reported in experiments recently [Angew. Chem. Int. Ed. 55 , 3611 (2016)]. In general thinking, interaction between two moieties of (CuSH)\begin{document}$ _{6} $\end{document} ring and (Au\begin{document}$ _{2} $\end{document} PH\begin{document}$ _{3} $\end{document} )\begin{document}$ _{2} $\end{document} in the Au\begin{document}$ _{2} $\end{document} @Cu\begin{document}$ _{6} $\end{document} nanocluster can be viewed as a d\begin{document}$ ^{10} $\end{document} -\begin{document}$ \sigma $\end{document} closed-shell interaction. However, chemical bonding analysis shows that there is a ten center-two electron (10c-2e) multicenter bonding between two moieties. Further comparative studies on other bimetallic nanocluster M\begin{document}$ _{2} $\end{document} @Cu\begin{document}$ _{6} $\end{document} (M = Ag, Cu, Zn, Cd, Hg) also revealed that multicenter bonding is the origin of electronic stability of the complexes besides the d\begin{document}$ ^{10} $\end{document} -\begin{document}$ \sigma $\end{document} closed-shell interaction. This will provide valuable insights into the understanding of closed-shell interactions. 相似文献
1000.
Qihao Wu Song‐Wei Li Heng Xu Hong Wang Pei Hu Hao Zhang Cheng Luo Kai‐Xian Chen Bastien Nay Yue‐Wei Guo Xu‐Wen Li 《Angewandte Chemie (International ed. in English)》2020,59(29):12105-12112
Placobranchus ocellatus is well known to produce diverse and complex γ‐pyrone polypropionates. In this study, the chemical investigation of P. ocellatus from the South China Sea led to the discovery and identification of ocellatusones A–D, a series of racemic non‐γ‐pyrone polyketides with novel skeletons, characterized by a bicyclo[3.2.1]octane ( 1 , 2 ), a bicyclo[3.3.1]nonane ( 3 ) or a mesitylene‐substituted dimethylfuran‐3(2H)‐one core ( 4 ). Extensive spectroscopic analysis, quantum chemical computation, chemical synthesis, and/or X‐ray diffraction analysis were used to determine the structure and absolute configuration of the new compounds, including each enantiomer of racemic compounds 1 – 4 after chiral HPLC resolution. An array of new and diversity‐generating rearrangements is proposed to explain the biosynthesis of these unusual compounds based on careful structural analysis and comparison with six known co‐occurring γ‐pyrones ( 5 – 10 ). Furthermore, the successful biomimetic semisynthesis of ocellatusone A ( 1 ) confirmed the proposed rearrangement through an unprecedented acid induced cascade reaction. 相似文献