Triumph Israels

von R. Freydan

Synthesis and optical characterization of unsymmetrical oligophenylenevinylenes

An efficient route to highly soluble unsymmetrical oligo(phenylenevinylenes) (OPVs) has been developed. The OPVs are end-substituted with donor alkoxy and acceptor sulfonyl groups for charge polarization and incorporate a methacrylate unit suitable for co-polymerization. The absorption and excitation spectra of the OPVs and their precursors have been examined; vibronic features are noted, and π-system lengthening and introduction of polarizing substituents red-shift the spectral maxima

Use of [(13)C-methyl]Tropinone to follow the fate of the methyl group during calystegine formation in root cultures of Solanum dulcamara (Solanaceae)

7th Joint Meeting of the Association-Francophone-pour-l'Enselgnement-et-la-Recherche-en-Pharmacog nosie/American-Society-of-Pharmacognosy/Society-for-Medicinal-Plant-Rese arch/Phytochem-Society-of-Europe/Societa-Italiana-di-Fitochimica, Athens, GREECE, AUG 03-08, 200

Structure of thermally treated oxadiazoleamide Langmuir-Blodgett films

The thermal treatment of Y-type Langmuir-Blodgett (LB) films formed from the amphiphilic derivative of 2,5-diphenyl-1,3,4-oxadiazole 1 results in changes of the molecular packing. These changes have been analysed by a combination of X-ray specular reflectivity data, X-ray grazing incidence diffraction data and scanning force microscopy images. On the basis of these experimental data we have simulated possible supramolecular structures. These simulations provide insight into the intermolecular interactions giving rise to the observed structural transitions. The crystalline structure induced by thermal treatment of the LB films is chracterized by a uniaxial texture, which is correlated with the dipping direction during deposition of the LB film

Optical properties of a nonlinear p-phenylenevinylene oligomer side chain polymer in films and fiber preforms

Linear and nonlinear optical properties of a new soluble polymer bearing distyrylbenzene chromophore, the alkoxy-sulphono-substituted p-phenylenevinylene oligomer (MTPV-ORSO) attached as a side-chain to the methyl methacrylate backbone are reported. This chromophore was developed for introduction into single-mode nonlinear optical polymer fibres. The molecular second-order and third-order nonlinearities were estimated with quantum chemical calculations (MOPAC). The side-chain polymer shows an optical absorption maximum at 326 nm. The polymer was incorporated into the core of the fibre preform with a procedure which led to a step index profile, as measured with a preform profiler, suitable for a single-mode optical fibre. Second harmonic of the fundamental 1200 nm wave was measured in the corona poled polymer films giving the second-order susceptibility d33 = 0.8 pm/V for the polymer containing about 1.3 wt% of the side-chain chromophore and 0.1 pm/V in a guest-host system containing 0.24 wt% of the chromophore in the fibre preform. The coherence length of the side-chain polymer, equal to 28 µm at 1200 nm, was evaluated from the dispersion of the linear refractive indices. Degenerate four-wave mixing (DFWM) with amplified femtosecond pulses was also applied to measure the nonlinear refractive index of the co-polymer at 800 nm