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31.
Maria Buchweitz Gennadi Gudi Reinhold Carle Dietmar R. Kammerer Hartwig Schulz 《Journal of Raman spectroscopy : JRS》2012,43(12):2001-2007
The FT‐Raman spectra of the chloride salts of pelargonidin‐3‐glucoside, cyanidin‐3‐glucoside and delphinidin‐3‐glucoside, their structures at pH 5.0 and their interaction with aluminium and ferric ions are presented for the first time and discussed with regard to their spectroscopic response. Two marker bands at approximately 1510 and 1330/1350 cm−1 and one band at approximately 1330/1350 cm−1 were identified being characteristic for the formation of ferric and aluminium chelates, respectively, of cyanidin‐3‐glucoside and delphinidin‐3‐glucoside. In contrast, pelargonidin‐3‐glucoside, exhibiting one single hydroxyl group in the B‐ring, did not form metal chelates, which could be clearly demonstrated by missing marker bands. The formation of anthocyanin–metal chelates was also verified in model systems containing commercial sugar beet pectin and a pectic polysaccharide fraction isolated thereof, respectively. In addition, the absence of anthocyanin–metal chelates in systems prepared with citrate buffer was confirmed, and the effects of low and high methoxylated citrus pectins on chelate formation were studied. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
32.
Clède S Lambert F Sandt C Gueroui Z Réfrégiers M Plamont MA Dumas P Vessières A Policar C 《Chemical communications (Cambridge, England)》2012,48(62):7729-7731
A rhenium tris-carbonyl derivative has been designed to couple infrared and luminescent detection in cells. Both spectroscopies are consistent with one another; they point out the reliability of the present SCoMPI (for Single Core Multimodal Probe for Imaging) for bimodal imaging and unambiguously indicate a localization at the Golgi apparatus in MDA-MB-231 breast cancer cells. 相似文献
33.
Lilo K. Mailnder Peter Lorenz Hannes Bitterling Florian C. Stintzing Rolf Daniels Dietmar R. Kammerer 《Molecules (Basel, Switzerland)》2022,27(23)
Matricaria recutita L., German chamomile, is one of the most widely used medicinal plants, whose efficacy has been proven in numerous studies. However, its roots have attracted only little interest so far, since mainly above-ground plant parts are used for medicinal purposes. To broaden the knowledge of chamomile roots, a profound phytochemical characterization was performed along with a bioactivity screening of corresponding root extracts. While volatile constituents such as chamomillol and polyynes were detected using GC-MS, HPLC-MSn analyses revealed the occurrence of four coumarin glycosides, more than ten phenolic acid esters and five glyceroglycolipids. Furthermore, the antioxidant activity of the extracts was evaluated. Polar extracts revealed IC50 values ranging from 13 to 57 µg/mL in the DPPH radical scavenging assay, which is in the same range as reported for chamomile flower extracts. In addition, superoxide radical scavenging potential and mild antibacterial effects against S. aureus und B. subtilis were demonstrated. Moreover, to assess interspecies variation in chamomile roots, extracts of M. recutita were compared to those of M. discoidea DC. Interestingly, the latter revealed stronger antioxidant activity. The presented results aim at the valorization of chamomile roots, previously discarded as by-product of chamomile flower production, as a sustainable source of bioactive phytochemicals. 相似文献
34.
Camille Houle Dr. Paul R. Savoie Clotilde Davies Damien Jardel Prof. Pier Alexandre Champagne Dr. Brigitte Bibal Prof. Jean-François Paquin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(46):10620-10625
We describe the first thiourea-catalyzed C−F bond activation. The use of a thiourea catalyst and Ti(OiPr)4 as a fluoride scavenger allows the amination of benzylic fluorides to proceed in moderate to excellent yields. Preliminary results with S- and O-based nucleophiles are also presented. DFT calculations reveal the importance of hydrogen bonds between the catalyst and the fluorine atom of the substrate to lower the activation energy during the transition state. 相似文献
35.
Jean-David Fermanian 《Journal of multivariate analysis》2003,85(1):156-191
In competing risks model, several failure times arise potentially. The smallest failure time and its index only are observed. Without specific assumptions, the joint or even the marginal distribution functions of the underlying failure times are not identifiable (A. Tsiatis, Proc. Natl. Acad. Sci. USA 72 (1975) 20). Nonetheless, if each individual is characterized by a “sufficiently informative” set of covariates, these distributions are identifiable under some conditions of regularity (J.J. Heckman and B. Honoré, Biometrika 76 (1989) 325). In this paper, nonparametric kernel estimators of the joint distribution function of failure times conditional on the covariates are proposed. Their weak and strong consistency are discussed. 相似文献
36.
The cross-coupling of aliphatic and aromatic thiols and aryl bromides/triflates mediated by a Pd2(dba)3/Xantphos catalytic system in refluxing xylene (140 °C) affords the corresponding aryl thioethers in good to excellent yields. 相似文献
37.
Seifallah Abid Yohan Gisbert Mitsuru Kojima Nathalie Saffon-Merceron Jrme Cuny Claire Kammerer Gwnaël Rapenne 《Chemical science》2021,12(13):4709
Mastering intermolecular gearing is crucial for the emergence of complex functional nanoscale machineries. However, achieving correlated motion within trains of molecular gears remains highly challenging, due to the multiple degrees of freedom of each cogwheel. In this context, we designed and synthesised a series of star-shaped organometallic molecular gears incorporating a hydrotris(indazolyl)borate anchor to prevent diffusion on the surface, a central ruthenium atom as a fixed rotation axis, and an azimuthal pentaporphyrinic cyclopentadienyl cogwheel specifically labelled to monitor its motion by non-time-resolved Scanning Tunneling Microscopy (STM). Desymmetrisation of the cogwheels was first achieved sterically, i.e. by introducing one tooth longer than the other four. For optimal mechanical interactions, chemical labelling was also investigated as a preferential way to induce local contrast in STM images, and the electronic properties of one single paddle were modulated by varying the porphyrinic scaffold or the nature of the central metal. To reach such a structural diversity, our modular synthetic approach relied on sequential cross-coupling reactions on a penta(p-halogenophenyl)cyclopentadienyl ruthenium(ii) key building block, bearing a single pre-activated p-iodophenyl group. Chemoselective Sonogashira or more challenging Suzuki–Miyaura reactions allowed the controlled introduction of the tagged porphyrinic tooth, and the subsequent four-fold cross-couplings yielded the prototypes of pentaporphyrinic molecular gears for on-surface studies, incorporating desymmetrised cogwheels over 5 nm in diameter.Star-shaped cogwheel prototypes incorporating one sterically- or chemically-labelled porphyrinic paddle were designed and synthesised with the aim of achieving intermolecular gearing on surfaces. 相似文献
38.
Dr. Sylvain Clède Prof. Dr. Clotilde Policar 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(3):942-958
Metal–carbonyl complexes are attractive structures for bio‐imaging. In addition to unique vibrational properties due to the CO moieties enabling IR and Raman cell imaging, the appropriate choice of ancillary ligands opens up the opportunity for luminescence detection. Through a classification by techniques, past and recent developments in the application of metal–carbonyl complexes for vibrational and luminescence bio‐imaging are reviewed. Finally, their potential as bimodal IR and luminescent probes is addressed. 相似文献
39.
Science China Mathematics - In this paper, we develop semi-classical analysis on H-type groups. We define semi-classical pseudodi fferential operators, prove the boundedness of their action on... 相似文献
40.
Paul Doukhan Jean-David Fermanian Gabriel Lang 《Statistical Inference for Stochastic Processes》2009,12(1):65-87
We state a multidimensional Functional Central Limit Theorem for weakly dependent random vectors. We apply this result to
copulas. We get the weak convergence of the empirical copula process and of its smoothed version. The finite dimensional convergence
of smoothed copula densities is also proved. A new definition and the theoretical analysis of conditional copulas and their
empirical counterparts are provided.
相似文献