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111.
Dr. Tatiana Suárez-Rodríguez Prof. Dr. Ángel L. Suárez-Sobrino Prof. Dr. Alfredo Ballesteros 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(51):13079-13084
Gold(I)-catalyzed formal [4+2] cycloaddition of O-aryl ynol ethers 1 and enol ethers 2 is described. This intermolecular reaction between two electron-rich unsaturated systems takes place, under mild conditions, in the presence of 5 mol% [IPrAu(CH3CN)]SbF6 as catalyst giving chromene derivatives with good yields. The cycloaddition is completely regio- and stereoselective, as well as versatile for both reactives. Silyl enol ethers can also react in the same way and under the same reaction conditions with quantitative yields. A plausible mechanism through a selective addition of the enol ether to the alkyne gold activated complex followed by an intramolecular aromatic electrophilic substitution is proposed. Several experimental results support the presence of a cationic oxonium intermediate prior to the aromatic substitution. The reaction represents a new entry to the chromene core. 相似文献
112.
Skripnikova Tatiana A. Starikova Anna A. Shumilova Galina I. Ermolenko Yuri E. Pendin Andrey A. Mourzina Yulia G. 《Journal of Solid State Electrochemistry》2017,21(8):2269-2279
Journal of Solid State Electrochemistry - We report a new type of solid-state electrode (type I) of a simple design with polyvinyl chloride membranes based on Mn(III) tetraphenylporphyrin and with... 相似文献
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[reaction: see text] A new and convenient three-step synthesis of pentafluorosulfanylbenzene from 1,4-cyclohexadiene with an overall yield of >70% is reported along with a number of derivatization reactions. 相似文献
116.
Yurij?Stoyan Guntram?ScheithauerEmail author Nikolay?Gil Tatiana?Romanova 《4OR: A Quarterly Journal of Operations Research》2004,2(1):69-84
Within two-dimensional cutting and packing problems with irregular shaped objects, the concept of
-functions has been proven to be very helpful for several solution approaches. In order to construct such
-functions a previous work, in which so-called primary objects are considered, is continued. Now
-functions are constructed for pairs of objects which can be represented as a finite combination (union, intersection, complement) of primary objects which allows the handling of arbitrary shaped objects by appropriate approximations of sufficient accuracy.Received: October 2002, Revised: October 2003, AMS classification:
65K05, 90C26, 90B06All correspondence to: Guntram Scheithauer 相似文献
117.
This review is a survey of the many scientific applications of ultrasonic broadbandspectrometry (absorption and velocity measurements with coherent sound waves)in liquids and liquid systems, covering, at present, a frequency range from nearly10 kHz to 10 GHz. Ultrasonic spectrometry has proved to be an almost universalresearch tool in many laboratories, one that is useful for investigation of variouschemical, biochemical, and physicochemical systems. Sound waves traversingliquids induce periodic perturbations in pressure and temperature, which can shiftequilibria, resulting in characteristic sound absorption and velocity dispersionspectra. An analysis of such spectra yields valuable information about thermodynamic and kinetic parameters of the particular system that is often difficult toobtain by other methods. Since such periodic perturbations imposed on the systemare incremental in nearly all cases, the system can be studied under equilibriumconditions. All nonlinear effects (heating, nonconstant fluid compressibility, andothers) are negligible, permitting, for instance, the application of linearized rateequations. In this review, various examples of measured broadband spectra arepresented. Related elementary processes are discussed. Among these are ionicand molecular reactions, including mechanisms of association and complexation,proton transfer, solvation, isomerization, interconversion, side-group rotation,hydrogen-bonding, as well as stacking processes and micelle formation. Specialattention will be given to the extensive research on chemical relaxation.Fundamental early and recent publications are cited and discussed. Many referencesare included with particular emphasis on less well known research and publicationsfrom countries of the former USSR. This review aims at a demonstration of thewidespread applications of modern ultrasonic techniques in many fields ofliquid-state research. 相似文献
118.
Petr I. Nikitin Petr M. Vetoshko Tatiana I. Ksenevich 《Journal of magnetism and magnetic materials》2007
A new type of biosensor has been developed based on detection of nanosized superparamagnetic particles that serve as labels in bioreactions. The method is based on non-linear magnetic material detection by a magnetic field having components at two frequencies f1 and f2. The response is measured at the combinatorial frequencies fi=mf1+nf2, where m and n are integers, e.g., fi=f1±2f2. Several highly sensitive readers of superparamagnetic particles have been designed and used for development of various formats of immunoassays, including those compatible with immunoconcentration and magnetic enrichment of antigens. 相似文献
119.
Ganeeva Yulia M. Yusupova Tatiana N. Okhotnikova Ekaterina S. 《Journal of Thermal Analysis and Calorimetry》2020,139(1):273-278
Journal of Thermal Analysis and Calorimetry - The bitumen-containing reservoir rocks taken from Devonian terrigenous formation of Romashkino and Bavly oil fields (Russia) were sampled and... 相似文献
120.
Dr. Aleksandr M. Agafontsev Dr. Tatiana A. Shumilova Dr. Aleksandr S. Oshchepkov Dr. Frank Hampel Prof. Dr. Evgeny A. Kataev 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(44):9991-9997
Pyrene-based cyclophanes have been synthesized with the aim to realize a bellows-type sensing mechanism for the ratiometric detection of nucleotide concentrations in a buffered aqueous solution. The sensing mechanism involves the encapsulation of a nucleobase between two pyrene rings, which affects the monomer-excimer equilibrium of the receptor in the excited state. The nature of the spacer and its connection pattern to pyrene rings have been varied to achieve high selectivity for ATP. The 1,8-substituted pyrene-based cyclophane with the 2,2’-diaminodiethylamine spacer demonstrates the best selectivity for ATP showing a 50-fold increase in the monomer-excimer emission ratio upon saturation with the nucleotide. The receptor can detect ATP within the biological concentrations range over a wide pH range. NMR and spectroscopic studies have revealed the importance of hydrogen bonding and stacking interactions for achieving a required receptor selectivity. The probe has been successfully applied for the real-time monitoring of creatine kinase activity. 相似文献