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911.
Jan Holec Dr. Jiří Rybáček Dr. Jaroslav Vacek Dr. Manfred Karras Dr. Lucie Bednárová Dr. Miloš Buděšínský Michaela Slušná Dr. Petr Holý Prof. Bernd Schmidt Dr. Irena G. Stará Dr. Ivo Starý 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(49):11494-11502
Racemic and highly enantioenriched 3-methoxycarbonyl, 3-carboxy, and 3-hydroxymethyl derivatives of dibenzo[6]helicene were prepared. The Langmuir layers of these helicenes were formed at the air–water interface and transferred onto solid substrates to afford Langmuir–Blodgett films, which were then studied by ambient atomic force microscopy and (chir)optical spectroscopy. Significant differences were found in the behaviour of the Langmuir layers as well as in the morphology, UV/Vis, electronic circular dichroism (ECD), and fluorescence spectra of the Langmuir–Blodgett thin films depending on the molecular chirality and nature of the polar group. The experimental results were supported by molecular dynamics simulations. 相似文献
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Luís M.N.B.F. Santos Luís M. Spencer S. Lima Carlos F.R.A.C. Lima Fernão D. Magalhães Manuel C. Torres Bernd Schröder Manuel A.V. Ribeiro da Silva 《The Journal of chemical thermodynamics》2011,43(6):834-843
A new Knudsen effusion apparatus, enabling simultaneous gravimetric and quartz crystal microbalance mass loss detection, is described. This device allows the measurement of vapour pressures of small sample mass (50 to 100) mg over a wide temperature range (350 to 650) K using very short effusion time intervals. The performance of the apparatus was checked by measuring the vapour pressures of anthracene, benzanthrone, and 1,3,5-triphenylbenzene, between (0.1 and 1) Pa, over temperature intervals of 20 K. The derived standard molar enthalpies of sublimation and vapour pressures are in excellent agreement with the mean of the available literature values and with the recommended values. The new working methodology and design of this apparatus allows the measurement of high quality vapour pressure data due to: accurate temperature measurement and control; improvement in vacuum thermal contact between the effusion cell and the oven metal block; optimisation of the quartz crystal sensor head microbalance position; efficient temperature control of the quartz crystal microbalance head; accurate measurement of the resonance crystal frequency using an impedance circuit analyser methodology. 相似文献
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JPC – Journal of Planar Chromatography – Modern TLC - 相似文献
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Markus Gellesch Franziska Hammerath Vicky Süß Marcel Haft Silke Hampel Sabine Wurmehl Bernd Büchner 《Journal of nanoparticle research》2017,19(9):307
The increasing interest in nanoscale materials goes hand in hand with the challenge to reliably characterize the chemical compositions and structural features of nanosized objects in order to relate those to their physical properties. Despite efforts, the analysis of the chemical composition of individual multi-element nanoparticles remains challenging—from the technical point of view as well as from the point of view of measurement statistics. Here, we demonstrate that zero-field solid-state nuclear magnetic resonance (NMR) complements local, single particle transmission electron microscopy (TEM) studies with information on a large assembly of chemically complex nanoparticles. The combination of both experimental techniques gives information on the local composition and structure and provides an excellent measurement statistic through the corresponding NMR ensemble measurement. This analytical approach is applicable to many kinds of magnetic materials and therefore may prove very versatile in the future research of particulate magnetic nanomaterials. 相似文献
919.
Bernd Trathnigg Muhammad Imran Malik Nicole Pircher Stephan Hayden 《Journal of separation science》2010,33(14):2052-2059
In ternary mobile phases consisting of acetone, methanol, and water, the retention of PEG on reversed‐phase columns is independent on molar mass at certain compositions of the mobile phase. Along this critical adsorption line, the retention of polypropylene glycol varies quite strongly, which can be utilized in the separation of block copolymers. Gradient elution along the critical line allows a baseline separation of all oligomers in polypropylene glycol up to approximately 25 propylene oxide units. The same resolution can be achieved in the separation of ethylene oxide‐propylene oxide block copolymers, regardless of the length of the ethylene oxide block. 相似文献
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