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81.
82.
Peter E. R. Blanchard Emily Reynolds Brendan J. Kennedy Chris D. Ling Zhaoming Zhang Gordon Thorogood Bruce C. C. Cowie Lars Thomsen 《Journal of synchrotron radiation》2014,21(6):1275-1281
Tc L3‐edge XANES spectra have been collected on powder samples of SrTcO3 (octahedral Tc4+) and NH4TcO4 (tetrahedral Tc7+) immobilized in an epoxy resin. Features in the Tc L3‐edge XANES spectra are compared with the pre‐edge feature of the Tc K‐edge as well as other 4d transition metal L3‐edges. Evidence of crystal field splitting is obvious in the Tc L3‐edge, which is sensitive to the coordination number and oxidation state of the Tc cation. The Tc L3 absorption edge energy difference between SrTcO3 (Tc4+) and NH4TcO4 (Tc7+) shows that the energy shift at the Tc L3‐edge is an effective tool for studying changes in the oxidation states of technetium compounds. The Tc L3‐edge spectra are compared with those obtained from Mo and Ru oxide standards with various oxidation states and coordination environments. Most importantly, fitting the Tc L3‐edge to component peaks can provide direct evidence of crystal field splitting that cannot be obtained from the Tc K‐edge. 相似文献
83.
Dr. Mariusz Tasior Vincent Hugues Dr. Mireille Blanchard‐Desce Prof. Daniel T. Gryko 《化学:亚洲杂志》2012,7(11):2656-2661
New, strongly fluorescent benzo[1,2‐d:4,5‐d′]bisimidazoles have been prepared by the reaction of Bandrowski′s base with various aldehydes. Their structures were carefully designed to achieve efficient excited‐state intramolecular proton transfer and good two‐photon‐absorption (2PA) cross‐sections. Functional dyes that possessed both high fluorescence quantum yields and large Stokes shifts were prepared. A π‐expanded D‐A‐D derivative that possessed Φfl=50 % and σ2=230 GM in the spectroscopic area of interest for biological imaging is an excellent candidate as a fluorescent probe. Thanks to the presence of two reactive amino groups, such compounds can be easily transformed into probes for bioconjugation. All of these benzo[1,2‐d:4,5‐d′]bisimidazoles were also strongly fluorescent in the solid state. 相似文献
84.
Dr. Cédric Rouxel Dr. Céline Le Droumaguet Yohan Macé Sophie Clift Dr. Olivier Mongin Dr. Emmanuel Magnier Dr. Mireille Blanchard‐Desce 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(39):12487-12497
Novel tripodal derivatives with a triphenylamine core and that bear “superacidifiers” (i.e., fluorinated sulfoximinyl blocks) or novel sulfiliminyl moieties as peripheral groups were synthesized. These new chromophores show strong absorption in the near‐UV region and emission in the visible region. The fluorinated sulfoximinyl moieties were found to behave as potent auxochromic and electron‐withdrawing (EW) groups, thus leading to redshifted absorption and emission. These moieties promote a core‐to‐periphery intramolecular charge transfer (ctp‐ICT) transition, the energy of which was found to be correlated to their EW strength. In this study, we provide evidence of a linear correlation between the Hammett constant (σp) values and the electronic gap between the ground and first excited state of the three‐branched derivatives. This in turn was used to derive σp values of fluorinated sulfoximinyl moieties. These EWGs show unprecedentedly high σp values, up to 1.45 relative to 0.8 for NO2. Also, by using this method, the sulfiliminyl moiety was shown to exhibit similar EW strength as NO2, while promoting improved transparency and solubility. Finally, the superior EW strength of the fluorinated sulfoximine peripheral moieties was shown to induce significant enhancement of the two‐photon absorption responses in the red near‐IR region of the three‐branched derivatives relative to similar octupoles that bear more usual strong EW groups. These characteristics (improved nonlinear responses or transparency) open new routes for the design of nonlinear optical (NLO) chromophores for optical limiting or electro‐optical modulation. Such building blocks could also be of interest for optoelectronic applications, including the development of solar cells. 相似文献
85.
PY Blanchard S Boisard M Dias T Breton C Gautier E Levillain 《Langmuir : the ACS journal of surfaces and colloids》2012,28(33):12067-12070
Electrochemical transduction without covalent links between redox and complexant units in a complexing self-assembled monolayer has been established. The results demonstrate that transduction depends on the crown ether/ferrocene ratio and appears to be tunable. 相似文献
86.
A Leliège CH Régent M Allain P Blanchard J Roncali 《Chemical communications (Cambridge, England)》2012,48(71):8907-8909
Donor-acceptor molecules with small chain extension have been synthesized and used as active material in organic solar cells. The effect of fusion of a phenyl group on the end dicyanovinylene acceptor is discussed. 相似文献
87.
Philippe Blanchard José M. Gracia‐Bondiacute;a Joseph C. Várilly 《International journal of quantum chemistry》2012,112(4):1134-1164
Forty‐five years after the point de départ [Hohenberg and Kohn, Phys Rev, 1964, 136, B864] of density functional theory, its applications in chemistry and the study of electronic structures keep steadily growing. However, the precise form of the energy functional in terms of the electron density still eludes us—and possibly will do so forever [Schuch and Verstraete, Nat Phys, 2009, 5, 732]. In what follows we examine a formulation in the same spirit with phase space variables. The validity of Hohenberg–Kohn–Levy‐type theorems on phase space is recalled. We study the representability problem for reduced Wigner functions, and proceed to analyze properties of the new functional. Along the way, new results on states in the phase space formalism of quantum mechanics are established. Natural Wigner orbital theory is developed in depth, with the final aim of constructing accurate correlation‐exchange functionals on phase space. A new proof of the overbinding property of the Müller functional is given. This exact theory supplies its home at long last to that illustrious ancestor, the Thomas–Fermi model. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012 相似文献
88.
BACKGROUND: Retaining glycosidases can catalyse glycosidic bond formation through transglycosylation from a donor sugar to an acceptor bound in the aglycone site. The aglycone specificity of a glycosidase is not easily determined, thereby complicating the choice of the most appropriate glycosidase for use as a catalyst for transglycosylation. We have developed a strategy to rapidly screen the aglycone specificity of a glycosidase and thereby determine which enzymes are best suited to catalyse specific transglycosylation reactions. RESULTS: The reactivation, or turnover, of a glycosidase trapped as a fluoroglycosyl-enzyme species is accelerated in the presence of a compound that productively binds to the aglycone site. This methodology was used to rapidly screen six glycosidases with 44 potential acceptor sugars. Validation of the screening strategy was demonstrated by the identification of products formed from a transglycosylation reaction with positively screened acceptors for four of the enzymes studied. CONCLUSIONS: The aglycone specificity of a glycosidase can be rapidly evaluated and requires only an appropriate fluorosugar inactivator, a substrate for assay of activity and a library of compounds for screening. 相似文献
89.
90.
Motoaki Kawanabe Masashi Sugiyama Gilles Blanchard Klaus-Robert Müller 《Annals of the Institute of Statistical Mathematics》2007,59(1):57-75
We consider high-dimensional data which contains a linear low-dimensional non-Gaussian structure contaminated with Gaussian
noise, and discuss a method to identify this non-Gaussian subspace. For this problem, we provided in our previous work a very
general semi-parametric framework called non-Gaussian component analysis (NGCA). NGCA has a uniform probabilistic bound on
the error of finding the non-Gaussian components and within this framework, we presented an efficient NGCA algorithm called
Multi-index Projection Pursuit. The algorithm is justified as an extension of the ordinary projection pursuit (PP) methods and is shown to outperform PP
particularly when the data has complicated non-Gaussian structure. However, it turns out that multi-index PP is not optimal
in the context of NGCA. In this article, we therefore develop an alternative algorithm called iterative metric adaptation for radial kernel functions (IMAK), which is theoretically better justifiable within the NGCA framework. We demonstrate that the new algorithm tends to outperform
existing methods through numerical examples. 相似文献