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.
Bibliographical noteFunding Information:
The work at the University of Ma?laga was supported by MINECO through project reference CTQ2012-33733 and by the Junta de Andaluci?a through research project P09-FQM-4708. The work at the Complutense University of Madrid was supported by European Research Council ERC- 320441 (Chirallcarbon), MINECO of Spain (CTQ2014-52045-R), and Comunidad Auto?noma of Madrid (FOTOCARBON project S2013/MIT-2841). T.M.P. acknowledges University of Minnesota, Morris (UMM) Faculty Research Enhancement Funds supported by the University of Minnesota Office of the Vice President for Research. L.E. thanks the Robert A. Welch Foundation, grant AH-0033, and the U.S. National Science Foundation, grants DMR-1205302 and CHE-1408865, for generous financial support. M.S. acknowledges the National Science Centre DEC-2013/10/A/ST4/00114 grant.
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