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981.
The Remarkable Effect of Halogen Substitution on the Membrane Transport of Fluorescent Molecules in Living Cells 下载免费PDF全文
Harinarayana Ungati Dr. Vijayakumar Govindaraj Prof. Dr. Govindasamy Mugesh 《Angewandte Chemie (International ed. in English)》2018,57(29):8989-8993
Small‐molecule‐based fluorescent probes have become important tools in biology for sensing and imaging applications. However, the biological applications of many of the fluorescent molecules are hampered by low cellular uptake and high toxicity. In this paper, we show for the first time that the introduction of halogen atoms enhances the cellular uptake of fluorescent molecules and the nature of halogen atoms plays a crucial role in the plasma membrane transport in mammalian cells. The remarkably higher uptake of iodinated compounds compared to that of their chloro or bromo analogues suggests that the strong halogen bonding ability of iodine atoms may play an important role in the membrane transport. This study provides a novel strategy for the transport of fluorescent molecules across the plasma membrane in living cells. 相似文献
982.
Electrochemical Reduction of Carbon Dioxide to Methanol on Hierarchical Pd/SnO2 Nanosheets with Abundant Pd–O–Sn Interfaces 下载免费PDF全文
Wuyong Zhang Qing Qin Dr. Lei Dai Ruixuan Qin Dr. Xiaojing Zhao Xumao Chen Daohui Ou Dr. Jie Chen Dr. Tracy T Chuong Prof. Binghui Wu Prof. Nanfeng Zheng 《Angewandte Chemie (International ed. in English)》2018,57(30):9475-9479
Electrochemical conversion of CO2 into fuels using electricity generated from renewable sources helps to create an artificial carbon cycle. However, the low efficiency and poor stability hinder the practical use of most conventional electrocatalysts. In this work, a 2D hierarchical Pd/SnO2 structure, ultrathin Pd nanosheets partially capped by SnO2 nanoparticles, is designed to enable multi‐electron transfer for selective electroreduction of CO2 into CH3OH. Such a structure design not only enhances the adsorption of CO2 on SnO2, but also weakens the binding strength of CO on Pd due to the as‐built Pd–O–Sn interfaces, which is demonstrated to be critical to improve the electrocatalytic selectivity and stability of Pd catalysts. This work provides a new strategy to improve electrochemical performance of metal‐based catalysts by creating metal oxide interfaces for selective electroreduction of CO2. 相似文献
983.
Floxuridine Homomeric Oligonucleotides “Hitchhike” with Albumin In Situ for Cancer Chemotherapy 下载免费PDF全文
Cheng Jin Hui Zhang Jianmei Zou Yan Liu Lin Zhang Fengjie Li Prof. Ruowen Wang Wenjing Xuan Prof. Mao Ye Prof. Weihong Tan 《Angewandte Chemie (International ed. in English)》2018,57(29):8994-8997
Automated attachment of chemotherapeutic drugs to oligonucleotides through phosphoramidite chemistry and DNA synthesis has emerged as a powerful technology in constructing structure‐defined and payload‐tunable oligonucleotide–drug conjugates. In practice, however, in vivo delivery of these oligonucleotides remains a challenge. Inspired by the systemic transport of hydrophobic payloads by serum albumin in nature, we report the development of a lipid‐conjugated floxuridine homomeric oligonucleotide (LFU20) that “hitchhikes” with endogenous serum albumin for cancer chemotherapy. Upon intravenous injection, LFU20 immediately inserts into the hydrophobic cave of albumin to form an LFU20/albumin complex, which accumulates in the tumor by the enhanced permeability and retention (EPR) effect and internalizes into the lysosomes of cancer cells. After degradation, cytotoxic floxuridine monophosphate is released to inhibit cell proliferation. 相似文献
984.
Lipase‐Catalyzed Dynamic Kinetic Resolution of C1‐ and C2‐Symmetric Racemic Axially Chiral 2,2′‐Dihydroxy‐1,1′‐biaryls 下载免费PDF全文
Dr. Gamal A. I. Moustafa Yasuhiro Oki Prof. Dr. Shuji Akai 《Angewandte Chemie (International ed. in English)》2018,57(32):10278-10282
We have discovered that the racemization of configurationally stable, axially chiral 2,2′‐dihydroxy‐1,1′‐biaryls proceeds with a catalytic amount of a cyclopentadienylruthenium(II) complex at 35–50 °C. Combining this racemization procedure with lipase‐catalyzed kinetic resolution led to the first lipase/metal‐integrated dynamic kinetic resolution of racemic axially chiral biaryl compounds. The method was applied to the synthesis of various enantio‐enriched C1‐ and C2‐symmetric biaryl diols in yields of up to 98 % and enantiomeric excesses of up to 98 %, which paves the way for new developments in the field of asymmetric synthesis. 相似文献
985.
The Importance of Excited‐State Energy Alignment for Efficient Exciplex Systems Based on a Study of Phenylpyridinato Boron Derivatives 下载免费PDF全文
Dr. Masashi Mamada Dr. Guojian Tian Prof. Hajime Nakanotani Prof. Jianhua Su Prof. Chihaya Adachi 《Angewandte Chemie (International ed. in English)》2018,57(38):12380-12384
Understanding excited‐state dynamics is critical for improving the photoluminescence (PL) efficiency of exciplexes. A series of exciplexes based on conventional hole‐transporting materials as donor and newly developed phenylpyridinato boron derivatives as acceptor were investigated. High PL efficiencies were achieved in only some combinations, and a large difference in performance among combinations provided insight into nonradiative processes in exciplex systems. Furthermore, the triplet local excited states (3LE) of each donor and acceptor were found play an important role in triplet exciplex harvesting. Significant contributions from triplets were clearly observed when the charge‐transfer excited states (1CT and 3CT) and 3LE were ideally aligned. We also demonstrated fine control of relative energy alignment via the concentration to improve the PL efficiency. 相似文献
986.
Coumaraz‐2‐on‐4‐ylidene: Ambiphilic N‐Heterocyclic Carbenes with a Tunable Electronic Structure 下载免费PDF全文
Hayoung Song Hyunho Kim Prof. Eunsung Lee 《Angewandte Chemie (International ed. in English)》2018,57(28):8603-8607
Herein, a coumaraz‐2‐on‐4‐ylidene ( 1 ) as a new example of an ambiphilic N‐heterocyclic carbene, having electronic properties that can be fine‐tuned, is reported. The N‐carbamic and aryl groups on the carbene carbon center provide exceptionally high electrophilicity and nucleophilicity simultaneously to the carbene center, as evidenced by the 77Se NMR chemical shifts of their selenoketone derivatives and the CO stretching strengths of their rhodium carbonyl complexes. Since the precursors of 1 could be synthesized from various functionalized Schiff bases in a practical and scalable manner, the electronic properties of 1 can be fine‐tuned in a quantitative and predictable way by using the Hammett σ constant of the functional groups on aryl ring. The facile electronic tuning capability of 1 may be applicable to eliciting novel properties in main‐group and transition‐metal chemistry. 相似文献
987.
988.
Isolated Platinum Atoms Stabilized by Amorphous Tungstenic Acid: Metal–Support Interaction for Synergistic Oxygen Activation 下载免费PDF全文
Qian Zhang Xi‐Xi Qin Fan‐Peng Duan‐Mu Prof. Hui‐Ming Ji Prof. Zhu‐Rui Shen Dr. Xiao‐Peng Han Prof. Wen‐Bin Hu 《Angewandte Chemie (International ed. in English)》2018,57(30):9351-9356
Oxygen activation plays a crucial role in many important chemical reactions such as oxidation of organic compounds and oxygen reduction. For developing highly active materials for oxygen activation, herein, we report an atomically dispersed Pt on WO3 nanoplates stabilized by in situ formed amorphous H2WO4 out‐layer and the mechanism for activating molecular oxygen. Experimental and theoretical studies demonstrate that the isolated Pt atoms coordinated with oxygen atoms from [WO6] and water of H2WO4, consequently leading to optimized surface electronic configuration and strong metal–support interaction (SMSI). In exemplified reactions of butanone oxidation sensing and oxygen reduction, the atomic Pt/WO3 hybrid exhibits superior activity than those of Pt nanoclusters/WO3 and bare WO3 as well as enhanced long‐term durability. This work will provide insight into the origin of activity and stability for atomically dispersed materials, thus promoting the development of highly efficient and durable single atom‐based catalysts. 相似文献
989.
The Role of Torsional Dynamics on Hole and Exciton Stabilization in π‐Stacked Assemblies: Design of Rigid Torsionomers of a Cofacial Bifluorene 下载免费PDF全文
Dr. Denan Wang Dr. Maxim V. Ivanov Dr. Damian Kokkin John Loman Jin‐Zhe Cai Prof. Scott A. Reid Prof. Rajendra Rathore 《Angewandte Chemie (International ed. in English)》2018,57(27):8189-8193
Exciton and charge delocalization across π‐stacked assemblies is of importance in biological systems and functional polymeric materials. To examine the requirements for exciton and hole stabilization, cofacial bifluorene ( F 2) torsionomers were designed, synthesized, and characterized: unhindered (model) Me F 2, sterically hindered tBu F 2, and cyclophane‐like C F 2, where fluorenes are locked in a perfect sandwich orientation via two methylene linkers. This set of bichromophores with varied torsional rigidity and orbital overlap shows that exciton stabilization requires a perfect sandwich‐like arrangement, as seen by strong excimeric‐like emission only in C F 2 and Me F 2. In contrast, hole delocalization is less geometrically restrictive and occurs even in sterically hindered tBu F 2, as judged by 160 mV hole stabilization and a near‐IR band in the spectrum of its cation radical. These findings underscore the diverse requirements for charge and energy delocalization across π‐stacked assemblies. 相似文献
990.
A Rapidly Self‐Healing Host–Guest Supramolecular Hydrogel with High Mechanical Strength and Excellent Biocompatibility 下载免费PDF全文
Dr. Ye Zhu Dr. Lijing Hao Dr. Yunhua Chen Prof. Dr. Geng An Prof. Dr. Hongkai Wu Prof. Dr. Xuetao Shi Prof. Dr. Chuanbin Mao 《Angewandte Chemie (International ed. in English)》2018,57(29):9008-9012
It is still a challenge to achieve both excellent mechanical strength and biocompatibility in hydrogels. In this study, we exploited two interactions to form a novel biocompatible, slicing‐resistant, and self‐healing hydrogel. The first was molecular host–guest recognition between a host (isocyanatoethyl acrylate modified β‐cyclodextrin) and a guest (2‐(2‐(2‐(2‐(adamantyl‐1‐oxy)ethoxy)ethoxy)ethoxy)ethanol acrylate) to form “three‐arm” host–guest supramolecules (HGSMs), and the second was covalent bonding between HGSMs (achieved by UV‐initiated polymerization) to form strong cross‐links in the hydrogel. The host–guest interaction enabled the hydrogel to rapidly self‐heal. When it was cut, fresh surfaces were formed with dangling host and guest molecules (due to the breaking of host–guest recognition), which rapidly recognized each other again to heal the hydrogel by recombination of the cut surfaces. The smart hydrogels hold promise for use as biomaterials for soft‐tissue repair. 相似文献