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51.
Separation of high and low frequencies is a known approximation in the theory of molecular vibrations. Accordingly the Teller-Redlich product rule for isotopic frequencies splits into separated product rules. A theorem states that the approximate frequency ratios for the high and low frequencies when multiplied together give the exact ratio for the whole set of frequencies. The theorem is illustrated by numerical computations for H2S2/D2S2 and proved mathematically for special cases as well as the general case. 相似文献
52.
Dr. Chloé Grazon Pedro Salas-Ambrosio Emmanuel Ibarboure Alix Buol Dr. Elisabeth Garanger Prof. Mark W. Grinstaff Prof. Sébastien Lecommandoux Dr. Colin Bonduelle 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(2):632-636
Reported here is the first aqueous ring-opening polymerization (ROP) of N-carboxyanhydrides (NCAs) using α-amino-poly(ethylene oxide) as a macroinitiator to protect the NCA monomers from hydrolysis through spontaneous in situ self-assembly (ISA). This ROPISA process affords well-defined amphiphilic diblock copolymers that simultaneously form original needle-like nanoparticles. 相似文献
53.
Dr. Chongwei Zhu Dr. Albert Poater Dr. Carine Duhayon Dr. Brice Kauffmann Dr. Alix Saquet Dr. Arnaud Rives Dr. Valérie Maraval Prof. Remi Chauvin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(36):9286-9291
After extensive studies of 1D and 2D skeletal carbo-mers based on C8 π-conjugating dialkynylbutatriene units (DABs: ∼C≡C−(R)C=C=C=C(R)−C≡C∼) bridging sp or sp2 centers in carbo-butene, carbo-xylylene or carbo-benzene derivatives, 3D versions are envisaged through carbo-barrelenes and partially reduced derivatives thereof where two or three DAB blades span a bridge between sp3 carbinol vertices or ether thereof. For R=Ph, stable representatives were synthesized through a pivotal [6]pericyclynedione, and extensively characterized by spectroscopic, electrochemical and crystallographic methods. Density functional theory calculations allow detailed analysis of structural and electronic features of the 7 Å high C26 barrel-shaped molecules, and show that they can behave as cages for ionic species. Beyond aesthetical concerns, the results could open prospects of applications in host-guest supramolecular chemistry and single molecule charge transport. 相似文献
54.
55.
T.B. Grimley 《Journal of Electron Spectroscopy and Related Phenomena》1983,30(1):229-235
This paper describes the goals of theoretical work on vibrations at surfaces, and comments on some of the contributions to VAS-82. Its main purpose however is to specify areas where theoretical work is urgently needed, and to identify some critical issues. Among the latter, the most important is the use of clusters to model atomic and molecular processes on solid surfaces. 相似文献
56.
Carbo‐Quinoids: Stability and Reversible Redox‐Proaromatic Character towards Carbo‐Benzenes
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Kévin Cocq Valérie Maraval Nathalie Saffon‐Merceron Alix Saquet Corentin Poidevin Christine Lepetit Remi Chauvin 《Angewandte Chemie (International ed. in English)》2015,54(9):2703-2706
The carbo‐mer of the para‐quinodimethane core is stable within in a bis(9‐fluorenylidene) derivative. Oxidation of this carbo‐quinoid with MnO2 in the presence of SnCl2 and ethanol affords the corresponding p‐bis(9‐ethoxy‐fluoren‐9‐yl)‐carbo‐benzene. The latter can be in turn converted back into the carbo‐quinoid by reduction with SnCl2, thus evidencing a chemical reversibility of the interconversion between a pro‐aromatic carbo‐quinoid and an aromatic carbo‐benzene, and is reminiscent of the behavior of the benzoquinone/hydroquinone redox couple (in the red–ox opposite sense). 相似文献
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58.
Abstract A complete normal coordinate analysis has been performed for the tricyanomethanide ion C(CN)? 3 for which a planar structure of symmetry D3h was assumed. The symmetric Fand internal f valence force constant matrices were derived in the general case by using a GVFF and the results are applied to C(CN)? 3. 相似文献
59.
Ruthenium Complexes with Dendritic Ferrocenyl Phosphanes: Synthesis,Characterization, and Application in the Catalytic Redox Isomerization of Allylic Alcohols
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Paul Neumann Dr. Hanna Dib Dr. Alix Sournia‐Saquet Toni Grell Dr. Marcel Handke Prof. Dr. Anne‐Marie Caminade Prof. Dr. Evamarie Hey‐Hawkins 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(17):6590-6604
An efficient system for the catalytic redox isomerization of the allylic alcohol 1‐octen‐3‐ol to 3‐octanone is presented. The homogeneous ruthenium(II) catalyst contains a monodentate phosphane ligand with a ferrocene moiety in the backbone and provides 3‐octanone in quantitative yields. The activity is increased by nearly 90 % with respect to the corresponding triphenyl phosphane ruthenium(II) complex. By grafting the catalyst at the surface of a dendrimer, the catalytic activity is further increased. By introducing different spacers between ferrocene and phosphorus, the influence on the electronic properties of the complexes is shown by evaluating the electrochemical behavior of the compounds. 相似文献
60.
Alix Toribio Emilie Destandau Claire Elfakir Michel Lafosse 《Rapid communications in mass spectrometry : RCM》2009,23(12):1863-1870
Online coupling of centrifugal partition chromatography to electrospray ionization mass spectrometry (CPC/ESI‐MS) was investigated for the separation and characterization of flavonol glycosides. Structural identification and purification monitoring of analytes on milligram scale were demonstrated to be possible by using an active flow‐splitter device which transfers automatically and successively, at discrete frequencies, small aliquots of the chromatographic effluent to an independent auxiliary stream directed to an ESI quadrupole mass spectrometer. The CPC protocol used a biphasic solvent system composed of ethyl acetate/ethanol/water (4.5:1:4.5, v/v/v) in isocratic mode. During the separation process, continuous acquisition of mass spectral data of the isolated flavonols from the effluent was performed in the negative ion mode with an auxiliary stream composed of 50 mM ammonium acetate/ethanol (2:8, v/v) delivered by a secondary pump. To demonstrate the potential of this hyphenated technique, flavonol glycosides from an apple peel extract were identified, purified and quantitatively analyzed. Calibration curves and limits of detection are also detailed. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献