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591.
Luca Marius Großmann Vera Beier Lea Duttenhofer Laura Lennartz Prof. Dr. Till Opatz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(54):e202201768
The ubiquity of amide bonds, present in natural products and common pharmaceuticals renders this functional group one of the most prevalent in organic chemistry. Despite its importance and a wide variety of existing methods for its formation, the latter still can be a challenge for classical activating reagents such as chloridating agents or carbodiimides. As the spent reagents often cannot be recycled, the development of more sustainable methods is highly desirable. Herein, we report an operationally simple and mild indirect electrochemical protocol to effect the condensation of carboxylic acids with amines, forming a wide variety of carboxamides. 相似文献
592.
Javier Lpez-Andarias Krikor Eblighatian Quentin T. L. Pasquer Lea Assies Naomi Sakai Sascha Hoogendoorn Stefan Matile 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2022,134(1):e202113163
Mechanosensitive flipper probes are attracting interest as fluorescent reporters of membrane order and tension in biological systems. We introduce PhotoFlippers, which contain a photocleavable linker and an ultralong tether between mechanophore and various targeting motifs. Upon irradiation, the original probe is released and labels the most ordered membrane that is accessible by intermembrane transfer. Spatiotemporal control from photocleavable flippers is essential to access open, dynamic or elusive membrane motifs without chemical or physical interference. For instance, fast release with light is shown to place the original small-molecule probes into the innermost leaflet of the nuclear envelope to image changes in membrane tension, at specific points in time of membrane trafficking along the secretory pathway, or in the inner leaflet of the plasma membrane to explore membrane asymmetry. These results identify PhotoFlippers as useful chemistry tools to enable research in biology. 相似文献
593.
Francis A. Carey Oliver D. Dailey Jr. 《Phosphorus, sulfur, and silicon and the related elements》2013,188(2):169-174
Abstract Deprotonation of 1,3-dithiolane 1-oxide (3) and trans-2-phenyl-1,3-dithiolane 1-oxide (5) leads to cleavage of the derived anions. Cleavage reactions do not occur with trans-hexahydro-1,3-benzodithiole (7), its 1-oxide, or its 1,1-dioxide all of which can be metalated and alkylated quantitatively at C-2. The preparation and reactions of the sulfoxides derived from 7 are not highly stereoselective. 相似文献
594.
595.
Lai N. Chan Courtenay Hart Lea Guo Tamara Nyberg Brandon S.J. Davies Loren G. Fong Stephen G. Young Brian J. Agnew Fuyuhiko Tamanoi 《Electrophoresis》2009,30(20):3598-3606
A recently developed proteomic strategy, the “GG‐azide”‐labeling approach, is described for the detection and proteomic analysis of geranylgeranylated proteins. This approach involves metabolic incorporation of a synthetic azido‐geranylgeranyl analog and chemoselective derivatization of azido‐geranylgeranyl‐modified proteins by the “click” chemistry, using a tetramethylrhodamine‐alkyne. The resulting conjugated proteins can be separated by 1‐D or 2‐D and pH fractionation, and detected by fluorescence imaging. This method is compatible with downstream LC‐MS/MS analysis. Proteomic analysis of conjugated proteins by this approach identified several known geranylgeranylated proteins as well as Rap2c, a novel member of the Ras family. Furthermore, prenylation of progerin in mouse embryonic fibroblast cells was examined using this approach, demonstrating that this strategy can be used to study prenylation of specific proteins. The “GG‐azide”‐labeling approach provides a new tool for the detection and proteomic analysis of geranylgeranylated proteins, and it can readily be extended to other post‐translational modifications. 相似文献
596.
Carey JR Suslick KS Hulkower KI Imlay JA Imlay KR Ingison CK Ponder JB Sen A Wittrig AE 《Journal of the American Chemical Society》2011,133(19):7571-7576
Rapid identification of both species and even specific strains of human pathogenic bacteria grown on standard agar has been achieved from the volatiles they produce using a disposable colorimetric sensor array in a Petri dish imaged with an inexpensive scanner. All 10 strains of bacteria tested, including Enterococcus faecalis and Staphylococcus aureus and their antibiotic-resistant forms, were identified with 98.8% accuracy within 10 h, a clinically important time frame. Furthermore, the colorimetric sensor arrays also proved useful as a simple research tool for the study of bacterial metabolism and as an easy method for the optimization of bacterial production of fine chemicals or other fermentation processes. 相似文献
597.
L Fohlmeister S Liu C Schulten B Moubaraki A Stasch JD Cashion KS Murray L Gagliardi C Jones 《Angewandte Chemie (International ed. in English)》2012,51(33):8294-8298
Not just any old iron! The reduction of a bulky guanidinato iron(II) bromide complex yields a three-coordinate iron(I) dimer that possesses the shortest Fe-Fe interaction (2.127??) reported to date. Magnetic, M?ssbauer, and computational studies show the unprecedented compound to contain two high-spin iron(I) centers with significant multiple-bond character. A related dimer containing a rare example of an unsupported, carbonyl-free Mn?Mn bond is also described. 相似文献
598.
599.
McIntire TM Smalley SR Newberg JT Lea AS Hemminger JC Finlayson-Pitts BJ 《Langmuir : the ACS journal of surfaces and colloids》2006,22(13):5617-5624
Alkylsiloxane self-assembled monolayers (SAMs) are used in the semiconductor industry and, more recently, as proxies for organics adsorbed on airborne mineral dust and on buildings and construction materials. A number of methods have been used for removing the SAM from the substrate after reaction or use, particularly plasmas or piranha (H2SO4/H2O2) solution. However, when the substrates are reused to make new SAMs, the impact of the cleaning methods on the chemistry of subsequently formed SAMs on the surface is not known. Here we report atomic force microscopy, X-ray photoelectron spectroscopy, Auger electron spectroscopy, and Fourier transform infrared studies of changes in a silicon substrate upon repetitive deposition and removal of SAMs by these two methods. It is shown that a thicker layer of silicon oxide is formed, and the surface becomes irregular and roughened, particularly after the piranha treatment. This layer of silica impacts the structure of the SAMs attached to it and can serve as a reservoir for trace gases that adsorb on it, potentially contributing to the subsequent reactions of the SAM. The implications for the use of such surfaces as a proxy for reactions of organics on airborne dust particles and on structures in the boundary layer are discussed. 相似文献
600.
Sustained resonance in a linear oscillator is achievable with a drive whose constant frequency matches the resonant frequency of the oscillator. But in oscillators with nonlinear restoring forces such as the pendulum, Duffing and Duffing-Van der Pol oscillator, the resonant frequency changes as the amplitude changes, so a constant frequency drive results in a beat oscillation instead of sustained resonance. Duffing-type nonlinear oscillators can be driven into sustained resonance, called autoresonance, when the drive frequency is swept in time to match the changing resonant frequency of the oscillator. We find that near-optimal drive linear sweep rates for autoresonance can be estimated from the beat oscillation resulting from constant frequency excitation. Specifically, a least squares estimate of the Teager-Kaiser instantaneous frequency versus time for the beat response to a stationary drive provides a near-optimal estimate of the nonstationary drive linear sweep rate needed to sustain resonance in the pendulum, Duffing and Duffing-Van der Pol oscillators. We confirm these predictions with model-based numerical simulations. An advantage of the beat method of estimating optimal drive sweep rates for maximal autoresonant response is that no model is required so experimentally generated beat oscillation data can be used for systems where no model is available. 相似文献