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951.
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
952.
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
953.
Yong Wang Yajun Zhao Shuaishuai Zhu Xingping Zhou Jing Xu Xiaolin Xie Rinaldo Poli 《Angewandte Chemie (International ed. in English)》2020,59(15):5988-5994
A strategy that uses carbon monoxide (CO) as a molecular trigger to switch the polymerization mechanism of a cobalt Salen complex [salen=(R,R)‐N,N′‐bis(3,5‐di‐tert‐butylsalicylidene)‐1,2‐cyclohexanediamine] from ring‐opening copolymerization (ROCOP) of epoxides/anhydrides to organometallic mediated controlled radical polymerization (OMRP) of acrylates is described. The key phenomenon is a rapid and quantitative insertion of CO into the Co?O bond, allowing for in situ transformation of the ROCOP active species (Salen)CoIII‐OR into the OMRP photoinitiator (Salen)CoIII‐CO2R. The proposed mechanism, which involves CO coordination to (Salen)CoIII‐OR and subsequent intramolecular rearrangement via migratory insertion has been rationalized by DFT calculations. Regulated by both CO and visible light, on‐demand sequence control can be achieved for the one‐pot synthesis of polyester‐b‐polyacrylate diblock copolymers (?<1.15). 相似文献
954.
Shuo Tao Xiaolei Li Xiaoge Wang Ying Wei Yunling Jia Jing Ju Yuanhui Cheng Huaisheng Wang Shuwen Gong Xingjun Yao Haixu Gao Cunyin Zhang Qiqi Zang Zhijian Tian 《Angewandte Chemie (International ed. in English)》2020,59(9):3455-3459
The synthesis of hierarchical nanosized zeolite materials without growth modifiers and mesoporogens remains a substantial challenge. Herein, we report a general synthetic approach to produce hierarchical nanosized single‐crystal aluminophosphate molecular sieves by preparing highly homogeneous and concentrated precursors and heating at elevated temperatures. Accordingly, aluminophosphate zeotypes of LTA (8‐rings), AEL (10‐rings), AFI (12‐rings), and ‐CLO (20‐rings) topologies, ranging from small to extra‐large pores, were synthesized. These materials show exceptional properties, including small crystallites (30–150 nm), good monodispersity, abundant mesopores, and excellent thermal stability. A time‐dependent study revealed a non‐classical crystallization pathway by particle attachment. This work opens a new avenue for the development of hierarchical nanosized zeolite materials and understanding their crystallization mechanism. 相似文献
955.
1,3‐Difunctionalizations of [1.1.1]Propellane via 1,2‐Metallate Rearrangements of Boronate Complexes
Songjie Yu Changcheng Jing Adam Noble Varinder K. Aggarwal 《Angewandte Chemie (International ed. in English)》2020,59(10):3917-3921
1,3‐Disubstituted bicyclo[1.1.1]pentanes (BCPs) are valuable bioisosteres of para‐substituted aromatic rings. The most direct route to these structures is via multicomponent ring‐opening reactions of [1.1.1]propellane. However, challenges associated with these transformations mean that difunctionalized BCPs are more commonly prepared by multistep reaction sequences with BCP‐halide intermediates. Herein, we report three‐ and four‐component 1,3‐difunctionalizations of [1.1.1]propellane with organometallic reagents, organoboronic esters, and a variety of electrophiles. This process is achieved by trapping intermediate BCP‐metal species with boronic esters to form boronate complexes, which are versatile intermediates whose electrophile‐induced 1,2‐metallate rearrangement chemistry enables a broad range of C?C bond‐forming reactions. 相似文献
956.
Jing Qi Feng‐Lian Zhang Ji‐Kang Jin Qiang Zhao Bin Li Lin‐Xuan Liu Yi‐Feng Wang 《Angewandte Chemie (International ed. in English)》2020,59(31):12876-12884
Radical borylation using N‐heterocyclic carbene (NHC)‐BH3 complexes as boryl radical precursors has emerged as an important synthetic tool for organoboron assembly. However, the majority of reported methods are limited to reaction modes involving carbo‐ and/or hydroboration of specific alkenes and alkynes. Moreover, the generation of NHC‐boryl radicals relies principally on hydrogen atom abstraction with the aid of radical initiators. A distinct radical generation method is reported, as well as the reaction pathways of NHC‐boryl radicals enabled by photoredox catalysis. NHC‐boryl radicals are generated via a single‐electron oxidation and subsequently undergo cross‐coupling with the in‐situ‐generated radical anions to yield gem‐difluoroallylboronates. A photoredox‐catalyzed radical arylboration reaction of alkenes was achieved using cyanoarenes as arylating components from which elaborated organoborons were accessed. Mechanistic studies verified the oxidative formation of NHC‐boryl radicals through a single‐electron‐transfer pathway. 相似文献
957.
Jing Zhang Meng Liu Chuanhua Wu Gaoyuan Zhao Peiqi Chen Lin Zhou Xingang Xie Ran Fang Huilin Li Xuegong She 《Angewandte Chemie (International ed. in English)》2020,59(10):3966-3970
The first total synthesis of the Euphorbia diterpenoid pepluanol B in both racemic and enantioenriched form involves 20 steps from a known bicyclic diol. This synthesis features an unprecedented bromo‐epoxidation to control the eight‐membered‐ring conformation. In addition, salient reactions for the construction of the tetracyclic backbone include a sterically challenging aldol reaction to establish the quaternary center, a ring closing metathesis (RCM) to forge the eight‐membered ring, and a diastereoselective cyclopropanation to assemble the embedded cyclopropane motif. 相似文献
958.
Yuanxin Li Jingjing Li Jing Sun Haonan He Bo Li Chao Ma Kai Liu Hongjie Zhang 《Angewandte Chemie (International ed. in English)》2020,59(21):8148-8152
Silk‐protein‐based fibers have attracted considerable interest due to their low weight and extraordinary mechanical properties. Most studies on fibrous proteins focus on the recombinant spidroins, but these fibers exhibit moderate mechanical performance. Thus, the development of alternative structural proteins for the construction of robust fibers is an attractive goal. Herein, we report a class of biological fibers produced using a designed chimeric protein, which consists of the sequences of a cationic elastin‐like polypeptide and a squid ring teeth protein. Remarkably, the chimeric protein fibers exhibit a breaking strength up to about 630 MPa and a corresponding toughness as high as about 130 MJ m?3, making them superior to many recombinant spider silks and even comparable to some native counterparts. Therefore, this strategy is a novel concept for exploring bioinspired ultrastrong protein materials through the development of new types of structural chimeric proteins. 相似文献
959.
Yuan Xu Jing Xue Qing Zhou Yongjun Zheng Xinghua Chen Songqin Liu Yanfei Shen Yuanjian Zhang 《Angewandte Chemie (International ed. in English)》2020,59(34):14498-14503
Emerging as a cost‐effective and robust enzyme mimic, nanozymes have drawn increasing attention with broad applications ranging from cancer therapy to biosensing. Developing nanozymes with both accelerated and inhibited biocatalytic properties in a biological context is intriguing to peruse more advanced functions of natural enzymes, but remains challenging, because most nanozymes are lack of enzyme‐like molecular structures. By re‐visiting and engineering the well‐known Fe‐N‐C electrocatalyst that has a heme‐like Fe‐Nx active sites, herein, it is reported that Fe‐N‐C could not only catalyze drug metabolization but also had inhibition behaviors similar to cytochrome P450 (CYP), endowing it a potential replacement of CYP for preliminary evaluation of massive potential chemicals, drug dosing guide, and outcome prediction. In addition, in contrast to electrocatalysts, the highly graphitic framework of Fe‐N‐C may not be obligatory for a competitive CYP‐like activity. 相似文献
960.
Principles of Surface Potential Estimation in Mixed Electrolyte Solutions:Taking into Account Dielectric Saturation
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The dielectric properties between in-particle/water interface and bulk solution are significantly different, which are ignored in the theories of surface potential estimation. The analytical expressions of surface potential considering the dielectric saturation were derived in mixed electrolytes based on the nonlinear Poisson-Boltzmann equation. The surface potentials calculated from the approximate analytical and exact numerical solutions agreed with each other for a wide range of surface charge densities and ion concentrations. The effects of dielectric saturation became important for surface charge densities larger than 0.30 C/m\begin{document}$ ^2 $\end{document} . The analytical models of surface potential in different mixed electrolytes were valid based on original Poisson-Boltzmann equation for surface charge densities smaller than 0.30 C/m\begin{document}$ ^2 $\end{document} . The analytical model of surface potential considering the dielectric saturation for low surface charge density can return to the result of classical Poisson-Boltzmann theory. The obtained surface potential in this study can correctly predict the adsorption selectivity between monovalent and bivalent counterions. 相似文献