Quantum Yield Measurement of Fluorescent Zeolite Nanopigments

Organic fluorescent molecules are infiltrated in the channels of zeolite L nanocrystals, thus creating organic-inorganic fluorescent nanoparticles. Combined with dielectric matrices, these fluorescent nanopigments open the way to the realization of novel optical devices. In this paper, the optical measurement of the quantum yield of fluorescent zeolites by means of a precise and reliable diffuse reflectance technique is presented. Several possible factors that may affect the fluorescence quantum yield are also investigated

Synthèse et caractérisation de polysilsesquioxanes bidimensionnels à partir de bis-silanetriols et de polysiloxanes organisés à partir de bis-silanediols

MONTPELLIER-BU Sciences (341722106) / SudocSudocFranceF

Asymmetric 1,3-Dipolar Cycloadditions of 2-Diazo-cyclohexane-1,3-diones and Alkyl Diazopyruvate

The 1,3-dipolar cycloaddition reactions of 2-diazocyclohexane-1,3-dione (7a; Table 1) and of alkyl diazopyruvates (11a-e; Table 3) to 2,3-dihydrofuran and other enol ethers have been investigated in the presence of chiral transition metal catalysts. With RhII catalysts, the cycloadditions were not enantioselective, but those catalyzed by [RuIICl2(1a)] and [RuIICl2(1b)] proceeded with enantioselectivities of up to 58% and 74% ee, respectively, when diazopyruvates 11 were used as substrates. The phenyliodonium ylide 7c yielded the adduct 8a in lower yield and poorer selectivity than the corresponding diazo precursor 7a (Table 2) upon decomposition with [Ru(pybox)] catalysts. This suggests that ylide decomposition by RuII catalysts, contrary to that of the corresponding diazo precursors, does not lead to Ru-carbene complexes as reactive intermediates. Our method represents the first reproducible, enantioselective 1,3-cycloaddition of these types of substrates

Rolic ® LCMO Photo Alignment Technology: Mechanism and Application to Large LCD Panels

Abstract. Rolic® Light Controlled Molecular Orientation (LCMO) technology is the basis for todays advanced mass production technologies for large LCD-TV panel, high-resolution 3D patterned-retarders and high-resolution optical security devices. This fundamental technology allows an easy achievement of high resolution azimuthal LC-director patterns with defined bias angles, from homogeneous planar to homeotropic orientation, depending on the target application Because of in-situ photo crosslinking during processing [1, 2], our proprietary LCMO photoalignment technology is shown to be thermally and optically stable. Last years, enormous progress has been made in the development of advanced materials that meet all requirements for mass production of large-area flat panel displays. LCMO-VA technology, for vertical alignment LCDs, is the basis for the state of the art UV 2 A production technology recently used in the manufacturing of advanced new generation LCD-TV panel displays with reduced production costs and low energy consumptio

Asymmetric cyclopropanations and cycloadditions of dioxocarbenes

Methods for enantioselective transfer of carbenes starting from precursors carrying two carbonyl groups have been elaborated. A one-pot procedure for olefin cyclopropanation with CH-acidic precursors via intermediate phenyliodonium ylides has been developed. The structure of the [Rh2{(S)-nttl}4] catalyst was optimized to produce up to 98% ee in olefin cyclopropanations with dimethyl malonate or Meldrum's acid. Highly selective Rh(II)-catalyzed olefin cyclopropanations could be observed upon replacement of methyl diazoacetoacetate by methyl (silyloxy­-vinyl)diazoacetate. Enantioselective dipolar cycloadditions of diazo­pyruvate to polar olefins have been realized with Ru(II)-pybox catalysts

Identifying Photoreaction Products in Cinnamate-Based Photoalignment Materials

A novel joint computational and experimental strategy is developed and applied for the detection and the identification of photoreaction products in cinnamate-based photoalignment materials. Based on NEXAFS, IR, and NMR spectroscopies and supported by computer simulation tools, this structural analysis method allows distinguishing the typical signatures of products resulting from UV-induced photoreactions between isomers of cinnamate-based model compounds. Besides deepening the understanding of typical photoalignment reaction products, the proposed strategy acquires technological relevance in supporting the realization of next generation materials for the LCD panel industry

Identifying Photoreaction Products in Cinnamate-Based Photoalignment Materials

A novel joint computational and experimental strategy is developed and applied for the detection and the identification of photoreaction products in cinnamate-based photoalignment materials. Based on NEXAFS, IR, and NMR spectroscopies and supported by computer simulation tools, this structural analysis method allows distinguishing the typical signatures of products resulting from UV-induced photoreactions between isomers of cinnamate-based model compounds. Besides deepening the understanding of typical photoalignment reaction products, the proposed strategy acquires technological relevance in supporting the realization of next generation materials for the LCD panel industry