Stilbenoid chromophores

Luminescent stilbenoid chromophores with diethoxysUane end groups were prepared via Heck reactions and characterized [49]. DiethoxysUane-substituted styrenes were used as vinylic components, thus allowing the combined cormection of the chromophore to the silane moiety with an extension of the 7t-system. Monodisperse... 

Micron- and submicron-scale lateral structures of optically nonlinear organic films comprised of substituted trons-stilbene derivatives (Ri = OCH3, R2 = CN) was characterized [45]. Second harmonic generation (SHG), optical microscopy, and atomic force microscopy (AFM) were used in this investigation. The third-order nonlinear optical properties and two-photon absorption ofdifferent types of stilbene derivatives (D-tt-D, A-7t-A, D-7t-A) were investigated [46]. Using the INDO/CI method, the UV-vis spectra were explored and the position and strength of the two-photon absorption were predicted by sum-over-states expression. Relationships of the structures, spectra, and nonlinear optical properties have been examined. Two-photon absorption spectra (650-1000 nm) of a series of asymmetrically substituted stilbenoid chromophores... 

A novel topological strategy has been examined for designing amorphous molecular solids suitable for optoelectronic applications. In this approach, chromophores were attached to a tetrahedral point of convergence. For instance, stilbenoid units were covalently linked to a tetraphenylmethane core by means of a palladium-catalyzed Suzuki coupling reaction [143]. The optical properties of these compounds were examined. 

The synthesis of tetraarylsilanes via Wurtz cross-coupling of bromoarenes and SiCU is a short and efficient route to tetraarylsilanes. Four conjugated units like biphenyl or naphthalene can be attached to the central silicon atom in high yield, but in the case of donor-substituted stilbenoid oligomers, this method gave only poor results [12]. For the preparation of tetrahedral silanes with phenylenevinylene chromophores, the convergent step was not performed on the central silicon atom but on a tetra- -tolylsilane (lb) functionalized with four phosphonic esters. The advantage of this approach is the additional extension of the n-system in the final step. 

Monodisperse oligo(phenylenevinylene)s are assembled to three-dimensional scaffolds in convergent three- or fourfold Homer reactions of a silane core and stilbenoid aldehydes in moderate to good yields. The central silane is sensitive toward nucleophilic attack. Tetrahedral compounds with short side chains form stable amorphous films but trigonal-pyramidal shaped assemblies tend to recrystallize. The connection of the chromophores to a central silicon atom results in a stabilization of the excited states an intense blue-green fluorescence is emitted from solution as well as from transparent films. 

Frequency upconversion of 800 nm ultrashort 175 fs optical pulses by two-photon absorption in a stilbenoid compound-doped polymer (PMMA) optical fiber was reported [28]. By the intensity-dependent transmission method, the two-photon absorption cross section was deduced. The combination of a well-designed organic chromophore incorporated into a fiber geometry is appealing for the development of an upconversion blue polymer laser. Upconversion fluorescence and optical power limiting effects based on the two- and three-photon absorption process of a frans-4,4 bis(pyrrolidinyl)stilbene were investigated [29]. The molecular TPA cross section three-photon absorption (3PA) cross section g3 at 720-1000 nm were measured. The 3PA-induced optical power-limiting properties were also illustrated at 980 nm. 

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