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951.
952.
Based on simple model calculations, the expected magnitude of the field‐induced shift observable in electroabsorption is estimated for three alternative assignments proposed in the literature for the lowest singlet excitation of the pentacene crystal (pure Frenkel exciton, pure charge‐transfer exciton, or a mixture of both). The results are compared with the corresponding experimental value, which is also known from the literature. The latter turns out to be compatible only with the mixed parentage of the pertinent state, which contains the charge‐transfer contribution in the range from 25 to 70 %. The conclusion is discussed in the context of the present controversies concerning the existing experimental and theoretical evidence on this subject. 相似文献
953.
Max Deimling Manuel Kirchhof Barbara Schwager Yaseen Qawasmi Alex Savin Dr. Tina Mühlhäuser Dr. Wolfgang Frey Dr. Birgit Claasen Dr. Angelika Baro Prof. Thomas Sottmann Prof. Sabine Laschat 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(40):9464-9476
The role of liquid confinement on the asymmetric Rh catalysis was studied using the 1,2-addition of phenylboroxine ( 2 ) to N-tosylimine 1 in the presence of [RhCl(C2H4)2]2 and chiral diene ligands as benchmark reaction. To get access to Rh complexes of different polarity, enantiomerically pure C2-symmetric p-substituted 3,6-diphenylbicyclo[3.3.0]octadienes 4 and diastereomerically enriched unsymmetric norbornadienes 5 and 6 carrying either the Evans or the SuperQuat auxiliary were synthesized. A microemulsion containing the equal amounts of H2O/KOH and toluene/reactants was formulated using the hydrophilic sugar surfactant n-octyl β-d -glucopyranoside (C8G1) to mediate the miscibility between the nonpolar reactants and KOH, needed to activate the Rh–diene complex. Prominent features of this organized reaction medium are its temperature insensitivity as well as the presence of water and toluene-rich compartments with a domain size of 55 Å confirmed by small-angle X-ray scattering (SAXS). Although bicyclooctadiene ligands 4 a , b , e performed equally well under homogeneous and microemulsion conditions, ligands 4 c , d gave a different chemoselectivity. For norbornadienes 5 , 6 , however, microemulsions markedly improved conversion and enantioselectivity as well as reaction rate, as was confirmed by kinetic studies using ligand 5 b . 相似文献
954.
955.
956.
A quick method for determination of equilibrium temperature of high temperature reactions, which is inexpensive and suitable for small industrial laboratories, is reported. Reaction of high temperature dissociation of calcium carbonate is used as example for quick method application. The method is based on calorimetric measurement, Hess Law, and thermodynamic calculations. The calibrated calorimeter is used to determine enthalpy change for reactions CaCO3(s)?+?HCl(l), Ca(s)?+?2HCl(l), and CaO(s)?+?2HCl(l). By application of Hess??s energy cycle, enthalpies of formation of calcium carbonate and calcium oxide were determined. Acquired results were used to calculate enthalpy change for carbonate dissociation reaction. Calculated enthalpy change value was used for free energy change in dependence of temperature and also for equilibrium constant in dependence of temperature calculation using equations derived from basic thermodynamic equations. Using this method, equilibrium temperature for calcium carbonate dissociation reaction is found to be equal to 1154.14?K, which confirms accuracy of the method. 相似文献
957.
Bankiewicz Barbara Wojtulewski Sławomir Markiewicz Karolina H. Wilczewska Agnieszka Z. 《Structural chemistry》2017,28(3):801-812
Structural Chemistry - The structural studies of carbamohydrazonothioate derivative and its hydrochloride solvate are the aim of hereunder presented research. The combination of the... 相似文献
958.
Development of easy‐to‐use reverse‐phase liquid chromatographic methods for determining PRE‐084, RC‐33 and RC‐34 in biological matrices. The first step for in vivo analysis of sigma1 receptor agonists
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Annamaria Marra Daniela Rossi Lauretta Maggi Federica Corana Barbara Mannucci Marco Peviani Daniela Curti Simona Collina 《Biomedical chromatography : BMC》2016,30(4):645-651
Over the years there has been a growing interest in the therapeutic potential for central nervous system pathologies of sigma receptor modulators. The widely studied PRE‐084 and our compounds RC‐33 and RC‐34 are very potent and selective sigma 1 receptor agonists that could represent promising drug candidates for Amyotrophic Lateral Sclerosis (ALS). Herein, we develop and validate robust and easy‐to‐use reverse‐phase chromatographic methods suitable for detecting and quantifying PRE‐084, RC‐33 and RC‐34 in mouse blood, brain and spinal cord. An HPLC/UV/ESI‐MS system was employed for analyzing PRE‐084 and an HPLC/UV‐PDA system for determining RC‐33 and RC‐34. Chromatographic separations were achieved on Waters Symmetry RP18 column (150 × 3.9 mm, 5 µm), eluting with water and acetonitrile (both containing 0.1% formic acid) in gradient conditions. The recovery of PRE‐084, RC‐33 and RC‐34 was >95% in all the considered matrices. Their limits of quantitation and detection were also determined. Validation proved the methods be suitable for separating tested compounds from endogenous interferences, being characterized by good sensitivity, linearity, precision and accuracy. A preliminary central nervous system distribution study showed a high distribution of RC‐33 in brain and spinal cord, with concentration values well above the determined limit of quantitation. The proposed methods will be used in future preclinical investigations. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
959.
Barbara Cardinali Gianluigi Lunardi Enrico Millo Andrea Armirotti Gianluca Damonte Aldo Profumo Stefania Gori Giuseppina Iacono Alessia Levaggi Lucia Del Mastro 《Analytical and bioanalytical chemistry》2014,406(18):4557-4561
Trastuzumab, a humanized monoclonal antibody directed against the epidermal growth factor receptor 2 (HER2), is a milestone in the treatment of HER2-overexpressing breast cancer patients. An enzyme-linked immunosorbent assay (ELISA) for trastuzumab has been developed for routine use in the laboratory to support clinical and pharmacokinetic studies to optimize therapy. The method relies on an antigen peptide linked to a 96-well plate via the streptavidin/biotin system. The peptide sequence mimics the extracellular portion of the HER2 receptor that is recognized by trastuzumab. The calibration range of the assay is 10 to 360 ng/mL per well, corresponding to a trastuzumab serum concentration from 5 to 180 μg/mL with a lower limit of quantification of 10 μg/mL. Validation results demonstrate that trastuzumab can be accurately and precisely quantified in human serum using this assay. The procedure was also tested in sera obtained from breast cancer patients to evaluate trastuzumab serum levels, confirming the applicability of method that could be a valid assay to use in daily laboratory practice. 相似文献
960.
Introducing an In Situ Capping Strategy in Systems Biocatalysis To Access 6‐Aminohexanoic acid
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Dr. Johann H. Sattler Dr. Michael Fuchs Dr. Francesco G. Mutti Barbara Grischek Dr. Philip Engel Dr. Jan Pfeffer Prof. Dr. John M. Woodley Prof. Dr. Wolfgang Kroutil 《Angewandte Chemie (International ed. in English)》2014,53(51):14153-14157
The combination of two cofactor self‐sufficient biocatalytic cascade modules allowed the successful transformation of cyclohexanol into the nylon‐6 monomer 6‐aminohexanoic acid at the expense of only oxygen and ammonia. A hitherto unprecedented carboxylic acid capping strategy was introduced to minimize the formation of the dead‐end intermediate 6‐hydroxyhexanoic acid. For this purpose, the precursor ε‐caprolactone was converted in aqueous medium in the presence of methanol into the corresponding methyl ester instead of the acid. Hence, it was shown for the first time that esterases—specifically horse liver esterase—can perform the selective ring‐opening of ε‐caprolactone with a clear preference for methanol over water as the nucleophile. 相似文献