共查询到20条相似文献,搜索用时 15 毫秒
1.
Dirk‐Peter Herten 《Chemie in Unserer Zeit》2008,42(3):192-199
Single‐molecule fluorescence spectroscopy evolved to a variety of tools to investigate molecular dynamics in thermodynamic equilibrium and to reveal subpopulations in heterogeneous molecular distributions which usually remain hidden in bulk experiments. Applications of single‐molecule experiments range from life sciences and material sciences to photo‐physics and photo‐chemistry. Some of these research fields, like chemical catalysis, have just recently been entered. This article summarizes major principles of single‐molecule fluorescence spectroscopy and gives an overview on some important applications up to the development of novel microscopic techniques with nanometer resolution. 相似文献
2.
Alex J. Plajer Felix J. Rizzuto Hao‐Che Niu Sanha Lee Jonathan M. Goodman Dominic S. Wright 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(31):10765-10769
Modern supramolecular chemistry is overwhelmingly based on non‐covalent interactions involving organic architectures. However, the question of what happens when you depart from this area to the supramolecular chemistry of structures based on non‐carbon frameworks remains largely unanswered, and is an area that potentially provides new directions in molecular activation, host–guest chemistry, and biomimetic chemistry. In this work, we explore the unusual host–guest chemistry of the pentameric macrocycle [{P(μ‐NtBu}2NH]5 with a range of anionic and neutral guests. The polar coordination site of this host promotes new modes of guest encapsulation via hydrogen bonding with the π systems of the unsaturated C≡C and C≡N bonds of acetylenes and nitriles as well as with the PCO? anion. Halide guests can be kinetically locked within the structure by oxidation of the phosphorus periphery by oxidation to PV. Our study underscores the future promise of p‐block macrocyclic chemistry. 相似文献
3.
Gisbert Schneider David E. Clark 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(32):10906-10917
Medicinal chemistry and, in particular, drug design have often been perceived as more of an art than a science. The many unknowns of human disease and the sheer complexity of chemical space render decision making in medicinal chemistry exceptionally demanding. Computational models can assist the medicinal chemist in this endeavour. Provided here is an overview of recent examples of automated de novo molecular design, a discussion of the concepts and computational approaches involved, and the daring prediction of some of the possibilities and limitations of drug design using machine intelligence. 相似文献
4.
Liang Chen Renjie Liu Xiang Hao Qiang Yan 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(1):270-274
The design of structurally dynamic molecular networks can offer strategies for fabricating stimuli‐responsive adaptive materials. Herein we first report a gas‐responsive dynamic gel system based on frustrated Lewis pair (FLP) chemistry. Two trefoil‐like molecules with bulky triphenylborane and triphenylphosphine groups are synthesized as complementary Lewis acid and base with trivalent sites. They can together bind CO2 gas molecules and further form a cross‐linked network via the bonding interactions between FLPs and CO2. Such CO2‐bridged dative linkages are shown to be dynamic covalent bonds, which endow the frustrated Lewis network with adaptable behaviors and unprecedented gas‐regulated viscoelastic, mechanical, and self‐healing performance. This study is an initial attempt to apply the FLP concept in materials chemistry, but we believe that this strategy will open a promising future for gas‐sensitive smart materials. 相似文献
5.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2018,130(20):5767-5770
Liquid crystal elastomers (LCEs) with intrinsic anisotropic strains are reversible shape‐memory polymers of interest in sensor, actuator, and soft robotics applications. Rapid gelation of LCEs is required to fix molecular ordering within the elastomer network, which is essential for directed shape transformation. A highly efficient photo‐cross‐linking chemistry, based on two‐step oxygen‐mediated thiol–acrylate click reactions, allows for nearly instant gelation of the main‐chain LCE network upon exposure to UV light. Molecular orientation from the pre‐aligned liquid crystal oligomers can be faithfully transferred to the LCE films, allowing for preprogrammed shape morphing from two to three dimensions by origami‐ (folding‐only) and kirigami‐like (folding with cutting) mechanisms. The new LCE chemistry also enables widely tunable physical properties, including nematic‐to‐ isotropic phase‐transition temperatures (TN‐I), glassy transition temperatures (Tg), and mechanical strains, without disrupting the LC ordering. 相似文献
6.
The economic cycle of aluminium is a didactical concept both for school and university. The student laboratory project presented allows the concrete implementation. Based on the simultaneous education between industry and didactics of chemistry is the illustrated teacher education. This concept is easily transferable to other topics, so that school, university and industry can interact more often with each other. 相似文献
7.
Xiaojuan Yu Paul Schwarz Alexei Nefedov Bernd Meyer Yuemin Wang Christof Wll 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(49):17915-17921
The surface chemistry of water on zinc oxides is an important topic in catalysis and photocatalysis. Interaction of D2O with anisotropic ZnO(10 0) surfaces was studied by IR reflection absorption spectroscopy using s‐ and p‐polarized light incident along different directions. Interpretation of the experimental data is aided using isotopologues and DFT calculations. The presence of numerous species is revealed: intact monomers, a mixed 2D D2O/OD adlayer, an anisotropic bilayer, and H‐bonded 3D structures. The isolated water monomers are identified unambiguously at low temperatures. The thermally induced diffusion of water monomers occurs at elevated temperatures, forming dimers that undergo autocatalytic dissociation via proton transfer. Polarization‐ and azimuth‐resolved IR data provide information on the orientation and strength of H‐bonds within the 2D and 3D structures. Ab initio molecular dynamics simulations reveal strong anharmonic couplings within the H‐bond network. 相似文献
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Wadih Ghattas Virginie Dubosclard Sybille Tachon Morane Beaumet Rgis Guillot Marius Rglier A. Jalila Simaan Jean‐Pierre Mahy 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(41):14747-14751
In the context of developing ecofriendly chemistry, artificial enzymes are now considered as promising tools for synthesis. They are prepared in particular with the aim to catalyze reactions that are rarely, if ever, catalyzed by natural enzymes. We discovered that 1‐aminocyclopropane carboxylic acid oxidase reconstituted with CuII served as an efficient artificial Diels–Alderase. The kinetic parameters of the catalysis of the cycloaddition of cyclopentadiene and 2‐azachalcone were determined (KM=230 μm , kapp=3 h?1), which gave access to reaction conditions that provided quantitative yield and >99 % ee of the (1S,2R,3R,4R) product isomer. This unprecedented performance was rationalized by molecular modeling as only one docking pose of 2‐azachalcone was possible in the active site of the enzyme and this was the one that leads to the (1S,2R,3R,4R) product isomer. 相似文献
10.
气相色谱中的超分子化学问题:Ⅰ.气相色谱与超分子化学的关系 总被引:1,自引:3,他引:1
超分子化学是有关超分子体系结构和功能的化学,超分子体系是由多个分子作用联系起来的实体,分子识别是形成超分本系的基本特征,本文从分子识别的角度,探讨了气相色谱学中超分子化学问题,并详细地评述了冠醚、液晶、环表固定液的分子识别机理的研究状况,最后,作者们大致展望了色谱研究超分子问题的前景,并且认为在多人工作基础上会产生一门新科学-超分子色谱学。 相似文献
11.
Elizabeth H. Krenske Craig M. Williams 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(36):10754-10758
Bredt’s rule holds a special place in the realm of physical organic chemistry, but its application to natural products chemistry—the field in which the rule was originally formulated—is not well defined. Herein, the use of olefin strain (OS) energy as a readily calculated predictor of the stability of natural products containing a bridgehead alkene is introduced. Schleyer first used OS energies to classify parent bridgehead alkenes into “isolable”, “observable”, and “unstable” classes. OS calculations on natural products, using contemporary forcefield methods, unequivocally predict all structurally verified bridgehead alkene natural products to be “isolable”. Thus, when one assigns the structure of a putative bridgehead alkene natural product, an OS in the “observable” or “unstable” ranges is a red flag for error. 相似文献
12.
Derek E. Williams Ekaterina A. Dolgopolova Danielle C. Godfrey Evgeniya D. Ermolaeva Perry J. Pellechia Andrew B. Greytak Mark D. Smith Stanislav M. Avdoshenko Alexey A. Popov Natalia B. Shustova 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2016,128(31):9216-9220
Herein, we report the first example of a crystalline metal–donor–fullerene framework, in which control of the donor–fullerene mutual orientation was achieved through chemical bond formation, in particular, by metal coordination. The 13C cross‐polarization magic‐angle spinning NMR spectroscopy, X‐ray diffraction, and time‐resolved fluorescence spectroscopy were performed for comprehensive structural analysis and energy‐transfer (ET) studies of the fulleretic donor–acceptor scaffold. Furthermore, in combination with photoluminescence measurements, the theoretical calculations of the spectral overlap function, Förster radius, excitation energies, and band structure were employed to elucidate the photophysical and ET processes in the prepared fulleretic material. We envision that the well‐defined fulleretic donor–acceptor materials could contribute not only to the basic science of fullerene chemistry but would also be used towards effective development of organic photovoltaics and molecular electronics. 相似文献
13.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(38):11533-11537
Dimethyl sulfoxide (DMSO) disrupts the hydrogen‐bond networks in water. The widespread use of DMSO as a cosolvent, along with its unusual attributes, have inspired numerous studies. Herein, infrared absorption spectroscopy of the S=O stretching mode combined with molecular dynamics and quantum chemistry models were used to directly quantify DMSO/water hydrogen‐bond populations in binary mixtures. Singly H‐bonded species are dominant at 10 mol %, due to strong DMSO–water interactions. We found an unexpected increase in non‐hydrogen‐bonded DMSO near the eutectic point (ca. 35 mol %) which also correlates with several abnormalities in the bulk solution properties. We find evidence for three distinct regimes: 1) strong DMSO–water interactions (<30 mol %), 2) ideal‐solution‐like (30–90 mol %), and 3) self‐interaction, or aggregation, regime (>90 mol %). We propose a “step in” mechanism, which involves hydrogen bonding between water and the DMSO aggregate species. 相似文献
14.
分子识别指导下的有机分子设计、合成和组装——世纪交替时代的有机化学 总被引:3,自引:2,他引:1
在21世纪即将来临之际,有机化学将面临生命科学、环境科学和材料科学越来越多的挑战。本文回顾了在分子识别指导下的有机分子的设计、合成和组装这个新领域的诞生和发展,认为这个领域将成为新世纪有机化学发展的一个重要方向。它的发展和应用不仅使得有机化学可能较好地面对新挑战,同时能推动有机合成化学自身的发展。 相似文献
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This overview features the chemical background on condensation phenomena of iron cations in aqueous solution. The formation of molecular clusters or nanosized solid phases is interpreted with illustrative mechanisms building a bridge between solution chemistry and solid state chemistry. Iron chemistry gives a very nice example of chemical versatility. 相似文献
17.
The imaging and manipulation capabilities of the scanning tunnelling microscope (STM) render possible a novel nanoscale chemistry based on experiments with single molecules. Herein, we address several aspects of a nanoscale stereochemistry using the STM. As an example, we investigate 1‐nitronaphthalene on Au(111). 1‐Nitronaphthalene becomes chiral upon planar adsorption on the metal surface. High‐resolution STM images reflect the asymmetric electronic structure of the molecules and allow for the determination of the absolute configuration of any individual molecule within complex molecular structures. At medium coverage, spontaneous breaking of the chiral symmetry results in the formation of homochiral conglomerates, while at high coverage racemic structures prevail. Finally, the tip of the STM is used to separate “supramolecule‐by‐supramolecule” a racemic mixture of chiral 1‐nitronaphthalene aggregates into the enantiopure compounds. 相似文献
18.
Polanski J Bak A Gieleciak R Magdziarz T 《Journal of chemical information and modeling》2006,46(6):2310-2318
Quantitative Structure Activity Relationship (QSAR) is a term describing a variety of approaches that are of substantial interest for chemistry. This method can be defined as indirect molecular design by the iterative sampling of the chemical compounds space to optimize a certain property and thus indirectly design the molecular structure having this property. However, modeling the interactions of chemical molecules in biological systems provides highly noisy data, which make predictions a roulette risk. In this paper we briefly review the origins for this noise, particularly in multidimensional QSAR. This was classified as the data, superimposition, molecular similarity, conformational, and molecular recognition noise. We also indicated possible robust answers that can improve modeling and predictive ability of QSAR, especially the self-organizing mapping of molecular objects, in particular, the molecular surfaces, a method that was brought into chemistry by Gasteiger and Zupan. 相似文献
19.
Benzoxaborole, as a versatile scaffold, plays important roles in organic synthesis, molecular recognition and supramolecular chemistry. It is also a privileged structure in medicinal chemistry due to its desirable physicochemical and drug-like properties. Recently, benzoxaboroles were widely applied as antifungal, antibacterial, antiviral, anti-parasite, and anti-inflammatory agents. This review covers the properties, synthetic methods and applications of benzoxaboroles in medicinal chemistry. 相似文献
20.
Bas van Genabeek Brigitte A. G. Lamers Craig J. Hawker E. W. Meijer Will R. Gutekunst Bernhard V. K. J. Schmidt 《Journal of polymer science. Part A, Polymer chemistry》2021,59(5):373-403
Precise oligomeric materials constitute a growing area of research with implications for various applications as well as fundamental studies. Notably, this field of science which can be termed macro-organic chemistry, draws inspiration from both traditional polymer chemistry and organic synthesis, combining the molecular precision of organic chemistry with the materials properties of macromolecules. Discrete oligomers enable access to unprecedented materials properties, for example, in self-assembled structures, crystallization, or optical properties. The degree of control over oligomer structures resembles many biological systems and enables the design of materials with tailored properties and the development of fundamental structure–property relationships. This Review highlights recent developments in macro-organic chemistry from synthetic concepts to materials properties, with a focus on self-assembly and molecular recognition. Finally, an outlook for future research directions is provided. 相似文献