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- PublicationAccès libre0.35 μm 22μW Multiphase Programmable Clock Generator for Circular Memory SC FIR Filter For Wireless Sensor Applications(2006-03-06)
- PublicationMétadonnées seulement1,1'-Dimethyl-2,2'-biimidazole(1999)
; Beauchamp, Andre L.Crystals of the title compd. are monoclinic, space group P21/n, with a 6.6760(10), b 5.5670(9), c 11.471(3) Å, ? 103.88(4)°; Z = 2, dc = 1.302; R = 0.036, Rw(F2) = 0.084 for 779 reflections,. The two rings are approx. coplanar. The mol. lies on a crystallog. inversion center and it adopts the anti conformation keeping the Me groups apart. [on SciFinder(R)] - PublicationMétadonnées seulement1,1'-Disubstituted ferrocene-containing thermotropic liquid crystals of structure [Fe{(?5-C5H4)COOC6H4XC6H4OCnH2n+1}2] (X = OOC or COO). Influence of the orientation of the central ester function on the mesogenic properties(1993)
; - PublicationAccès libre1,1′-Ferrocene dicarboxylic acid pyridin-4-yl ester: A new bidentate ligand in arene ruthenium chemistry(2007)
; 1,1′-Ferrocene dicarboxylic acid pyridin-4-yl ester (1) is prepared from 1,1′-ferrocene dicarbonyl chloride and 4-hydroxypyridine. This new bidentate ferrocenoyl ligand reacts with the monocationic complex [(η6-p-cymene)2Ru2 (μ-OH)3]+ to give the dicationic complex [(η6-p-cymene)2Ru2(μ-OH)2(1,1′- (NC5H4–OOC)2–Fc)]2+ (2) (Fc: C5H4–Fe–C5H4), isolated as a tetrafluoroborate salt. The single-crystal X-ray structure analysis of [2][BF4] 2 reveals the ferrocenoyl pyridine ligand 1 to act as μ2-η2 chelating ligand in the dinuclear complex, having replaced a μ2-η1-hydroxo ligand. - PublicationAccès libre1,2-Bis-N-[2’-(diphenylphosphanyl)benzoyl]diaminobenzene, a New Chelating Ligand with Versatile Coordination Properties(2003)
; 1,2-Bis-N-[2’-(diphenylphosphanyl)benzoyl]diaminobenzene (dppbH; 1) was prepared by peptidic coupling and shown to exist, in the solid state, in the form of hydrogen-bonded dimers by single-crystal X-ray structure analysis. As expected, 1 reacts with [MCl2 (cod)] (M = Pd, Pt; cod = cyclooctadiene) to form square-planar complexes. However, in the case of palladium [PdCl2 (dppbH)] (2) is obtained, while in the case of platinum [Pt(dppb)] (3) is formed. Thus, the nature of the metal induces a completely different coordination mode: In 2, the dppbH ligand only coordinates through the two phosphorus atoms, while in 3 a dppb ligand, formed by deprotonation of the two amino functions in dppbH, coordinates through the two phosphorus atoms and through the two nitrogen atoms. The single-crystal X-ray analyses of the two square-planar complexes reveal 2 to contain the two phosphorus atoms in a trans coordination mode and 3 to contain the two phosphorus atoms in a cis coordination mode. - PublicationMétadonnées seulement1,3-Butadienyl Thiocyanates in the Diels-Alder Reaction followed by a [3,3]-sigmatropic Shift(1986)
- PublicationAccès libre1,3-Butadienyl-thiocyanate in der Diels-Alder-Reaktion mit anschliessender [3,3]-sigmatroper Umlagerung(1986)
- PublicationAccès libre1,3-Dipolar cycloadditions: click chemistry for a new synthesis of 5-substituted tetrazoles and applications in organocatalysis(2007)
; Sedelmeier, GottfriedLes besoins récents en chimie organique de synthèse appliquée focalisent les efforts des chercheurs au développement de nouvelles voies efficaces et versatiles pour la préparation de molécules bioactives, en prenant en comptes en particulier les critères économiques et environnementaux. Nous avons développé une méthode novatrice et écologique pour la préparation de tetrazoles 141,142. Ce groupe fonctionnel trouve des applications dans des domaines variés allant des matériaux aux explosifs, et est d’un intérêt tout particulier en chimie médicinale 1. Cette importance a conduit au développement de diverses méthodes de préparation des tétrazoles, toutes présentant cependant des désavantages majeurs comme l’utilisation de réactifs toxiques ou explosifs, entre autres. La méthode alternative que nous avons développée permet la formation de tétrazoles à partir de nitriles en utilisant des azides de dialkylaluminium, qui possèdent l’avantage d’être des réactifs bon marché et non toxiques et permettent la préparation d’une large variété de tétrazoles de façon très efficace, adaptable à l’échelle industrielle. Nous avons ensuite appliqué cette méthodologie à l’organocatalyse 142, c'est-à-dire à la préparation et l’étude de molécules organiques ayant la faculté de catalyser des transformations chimiques très sélectives, procédé particulièrement attractif d’un point de vu environnemental et économique en constant développement., Tetrazoles are a class of heterocycles with a wide range of applications in medicinal chemistry and in material sciences 1. However a versatile method to synthesize tetrazoles through safe protocols is still highly desirable. Indeed each of the general known procedures uses either toxic metals, expensive reagents, harsh reaction conditions and may lead to the formation of dangerous hydrazoic acid or explosive sublimates. We report herein the discovery and development of a novel efficient process for transforming a wide variety of nitriles into the corresponding tetrazoles in high yield, using a simple and safe protocol. It has been found that the organoaluminum azides are affective reagents for the direct conversion of nitriles to tetrazoles. The organic soluble dialkylaluminum azides are prepared in a short time (4-6 h, r.t.) from the corresponding cheap dialkylaluminum chlorides. The cycloaddition occurs under mild conditions, and it is possible to synthesize a broad range of tetrazole derivatives with a high selectivity. This methodology can be applied to the synthesis of the pyrrolidine tetrazole, a versatile alternative of proline in organocatalysis. A variety of new catalysts based on pyrrolidine tetrazole skeleton are therefore efficiently prepared and tested. - PublicationMétadonnées seulement1,3-Disubstituted ferrocene-containing thermotropic liquid crystals of form (?5-C5H5)Fe[(?5-C5H3)-1,3-(CO2C6H4CO2C6H4OCnH2n+1)2](1994)
; - PublicationMétadonnées seulement1,3-Disubstituted ferrocene-containing thermotropic liquid crystals: synthesis, mesomorphic properties and the crystal and molecular structure(1993)
; - PublicationMétadonnées seulement1,4-Bis(hex-yloxy)-2,5-diiodo-benzene(2010)
; ; - PublicationMétadonnées seulement1,4-Bis(hexyloxy)-2,5-diiodobenzene(2010)
; ; - PublicationMétadonnées seulement1,4-Bis[4-(tert-butyl-diphenyl-silyl)buta-1,3-diyn-yl]benzene(2010)
; ; The title centrosymmetric mol-ecule, C(46)H(42)Si(2), is composed of a central benzene ring with buta-1,3-diynyl chains at positions 1 and 4. These chains are terminated by tert-butyl-diphenyl-silyl groups, hence the molecule is dumbbell in shape. The mol-ecules are connected via C-H(midline ellipsis)? inter-actions in the structure, so forming an undulating two-dimensional network in the bc plane. There is also a weak ?-? inter-action involving centrosymmetrically related phenyl rings with a centroid-centroid distance of 3.8359 (11) Å. - PublicationMétadonnées seulement1,4-Bis[4-(tert-butyldiphenylsilyl)buta-1,3-diynyl]benzene(2010)
; ; The title centrosym. mol., C46H42Si2, is composed of a central benzene ring with buta-1,3-diynyl chains at positions 1 and 4. These chains are terminated by tert-butyldiphenylsilyl groups, hence the mol. is dumbbell in shape. The mols. are connected via C-H...? interactions in the structure, so forming an undulating 2D network in the bc plane. There is also a weak ?-? interaction involving centrosym. related Ph rings with a centroid-centroid distance of 3.8359(11) Å. Crystal data: monoclinic, P21/c, a = 8.535(1), b = 17.2060(14), c = 13.4923(14) Å, ? = 104.064(9)°, Z = 2, 3260 obsd. reflections with I > 2(I), 220 refined parameters, R[F2 > 2?(F2)] = 0.044, wR(F2) = 0.104. [on SciFinder(R)] - PublicationAccès libre1-Methoxycarbonyl-substituiertes 2,3-Dihydropyridin-4(1H)-on (= Methyl-1,2,3,4-tetrahydro-4-oxopyridin-1-carboxylat) als Chromophor für die photochemische [2 + 2]-Cycloaddition(1991)
- PublicationAccès libre1-Octen-3-Ol Isolated from Bont Ticks Attracts Amblyomma variegatum(2001)
; Syed, ZainulabeudinVolatiles from various life-stages of the bont ticks Amblyomma variegatum and A. hebraeum were collected by using solid-phase microfibers and charcoal traps. An octenol isomer was found to be a major constituent of most of the tick material sampled and was identified as 1-octen-3-ol by gas chromatography–mass spectrometry and by using antenna of the tsetse fly Glossina brevipalpis in gas chromatography-linked antennogram detection. Release of this compound increased during molt to adulthood and following mechanical disturbance of adult ticks. (R)-(–)-1-Octen-3-ol and racemate 1-octen-3-ol both induce an increase in upwind walk to the odor source from A. variegatum in an airstream on a servosphere. Volatiles from tick exuviae plus feces and from dead ticks also attracted A. variegatum, suggesting that 1-octen-3-ol may contribute to the aggregation response of Amblyomma spp. on such substrates. 2,6-Dichloroanisol and 2,5-dimethylpyrazine also were detected in volatiles from the ticks but induced no behavioral responses on the servosphere. The suspected tick pheromone component, 2,6-dichlorophenol, was detected from A. variegatum adults cut into pieces but had no effect on the behavior of A. variegatum on the servosphere at a range of doses. - PublicationAccès libre1.55 µm InAs/GaAs Quantum Dots and High Repetition Rate Quantum Dot SESAM Mode-locked Laser
; - PublicationAccès libre10 kHz linewidth mid-infrared quantum cascade laser by stabilization to an optical delay lineWe present a mid-infrared quantum cascade laser (QCL) with a sub-10 kHz full width at half-maximum linewidth (at 1 s integration time) achieved by stabilization to a free-space optical delay line. The linear range in the center of a fringe detected at the output of an imbalanced Mach–Zehnder interferometer implemented with a short free-space pathlength difference of only 1 m is used as a frequency discriminator to detect the frequency fluctuations of the QCL. Feedback is applied to the QCL current to lock the laser frequency to the delay line. The application of this method in the mid-infrared is reported for the first time, to the best of our knowledge. By implementing it in a simple self-homodyne configuration, we have been able to reduce the frequency noise power spectral density of the QCL by almost 40 dB below 10 kHz Fourier frequency, leading to a linewidth reduction by a factor of almost 60 compared to the free-running laser. The present limits of the setup are assessed and discussed.