Enhanced functionality for donor-acceptor oligothiophenes via Inclusion of BODIPY : synthesis, electrochemistry, photophysics and model chemistry

We have synthesized several new push-pull oligothiophenes based on the BODIPY moiety as the electron acceptor and the well known oligothiophenes substituted with N,N-dialkylamino groups to enhance the electron donor ability. A complete characterization of the electronic properties has been done consisting of their photophysical, electrochemical and vibrational properties. The compounds have been studied after chemical treatment with acids and after oxidation. In this regard, they can be termed as NIR dyes and amphoteric redox electroactive molecules. We have described the presence of dual fluorescence in these molecules and fluorescence quenching either by energy transfer or, in the push-pull molecules, by the electron exchange. The combination of electrochemical and proton reversibility combined with the interesting optical properties of the new species offer an interesting platform for sensor and material applications.DGES, MEC (Spain) and Fundação para a Ciência e a Tecnologia (FCT

Fingerprints of Through-Bond and Through-Space Exciton and Charge π-Electron Delocalization in Linearly Extended [2.2]Paracyclophanes

New stilbenoid and thiophenic compounds terminally functionalized with donor–donor, acceptor–acceptor, or donor–acceptor moieties and possessing a central [2.2]­paracyclophane unit have been prepared, and their properties interpreted in terms of through-bond and through space π-electron delocalization (i.e., π-conjugations). Based on photophysical data, their excited-state properties have been described with a focus on the participation of the central [2.2]­paracyclophane in competition with through-bond conjugation in the side arms. To this end, two-photon and one-photon absorption and emission spectroscopy, as a function of temperature, solvent polarity, and pressure in the solid state have been recorded. Furthermore, charge delocalization through the [2.2]­paracyclophane in the neutral state and in the oxidized species (radical cations, dications and radical trications) has been investigated, allowing the elucidation of the vibrational Raman fingerprint of through-space charge delocalization. Thus, a complementary approach to both “intermolecular” excitation and charge delocalizations in [2.2]­paracyclophane molecules is shown which can serve as models of charge and exciton migration in organic semiconductors