| Abstract
| - This paper describes the synthesis and the X-ray and the opticalcharacterization ofconjugated soluble polymers in which the planarity of the backbone hasbeen improved by intramolecularH bonds. The solubility of the polymers was enhanced by increasingthe number of alkyl chains on thearyl group. The electron density on the phenyl ring was alsomodified by the amino and ester groups,introducing electron-donor or electron-acceptor groups, which alsoincrease the polarizability. Thepolymers have been synthesized by polycondensation using apalladium-catalyzed coupling reaction,between a bromoaryl and an ethynylaryl unit, with HBr elimination.This method allows the insertionof a triple bond between two phenyl groups. It was initially usedin our laboratory to obtain oligomersor high molecular weight polymers, having important nonlinearsusceptibilities. The new polymers havebeen characterized by UV−visible and Raman spectroscopies, as well asnonlinear optical measurementsof the third-order susceptibilities (χ(3)). Thesemeasurements allowed us to show the influence of the Hbonds between the aryl groups on the absorption wavelength. Inaddition, the nonlinear opticalmeasurements show that the χ(3) value of the pPY (6.8 ×10-10 esu) is close to the highest valuesobtainedin acetylenic polymers such as polydiacetylenes.
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