Synthesis of Bis(arylethynyl)pyrrolo[3,2-b]pyrroles and Effect of Intramolecular Charge Transfer on Their Photophysical Behavior - CNRS - Centre national de la recherche scientifique Accéder directement au contenu
Article Dans Une Revue Chemistry - A European Journal Année : 2019

Synthesis of Bis(arylethynyl)pyrrolo[3,2-b]pyrroles and Effect of Intramolecular Charge Transfer on Their Photophysical Behavior

Résumé

3,6-Bis(arylethynyl)pyrrolo[3,2-b]pyrroles were synthesized through a two-step procedure involving double direct alkynylation of the electron-rich core followed by Sonogashira coupling. In comparison with the parent tetraarylo-pyrrolo[3,2-b]pyrroles and benzo-fused pyrrolopyrroles, these new dyes showed moderately redshifted absorption. Almost all derivatives showed positive fluorescence solvatochromism and, for the first time, red-emitting pyrrolopyrroles were obtained. Computational studies revealed that, in most cases, there is negligible change in the geometry between ground and excited states. Interestingly, there was a fundamental difference between pyrrolopyrroles possessing electron-withdrawing substituents at positions 2 and 5 and their analogs lacking these substituents. The former dyes behaved like dipolar chromophores with the lowest excited state both one-photon and two-photon allowed, which corresponds to intramolecular charge transfer occurring along the branches perpendicular to the pyrrolopyrrole long axis. In compounds lacking electron-withdrawing substituents at positions 2 and 5, intramolecular charge transfer took place along the long axis of pyrrolopyrrole and consequently the one-photon transitions are not two-photon allowed. Despite displaying quadrupolar core-to-peripheral intramolecular charge transfer, these derivatives showed two-photon absorption cross sections in the NIR1 region comparable to tetraaryl-pyrrolo[3,2-b]pyrroles lacking pi-expansion (up to about 500 GM).

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Chimie
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Dates et versions

hal-02140868 , version 1 (27-05-2019)

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Mariusz Tasior, Guillaume Clermont, Mireille Blanchard-Desce, Denis Jacquemin, Daniel T. Gryko. Synthesis of Bis(arylethynyl)pyrrolo[3,2-b]pyrroles and Effect of Intramolecular Charge Transfer on Their Photophysical Behavior. Chemistry - A European Journal, 2019, 25 (2), pp.598-608. ⟨10.1002/chem.201804325⟩. ⟨hal-02140868⟩
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