Self-association and electron transfer in donor-acceptor dyads connected by meta-substituted oligomers
Molina-Ontoria A, Fernandez G, Wielopolski M, Atienza C, Sanchez L, Gouloumis A, Clark T, Martin N, Guldi DM (2009)
Publication Type: Journal article, Original article
Publication year: 2009
Journal
Original Authors: Molina-Ontoria A., Fernandez G., Wielopolski M., Atienza C., Sanchez L., Gouloumis A., Clark T., Martin N., Guldi D.M.
Publisher: American Chemical Society
Book Volume: 131
Pages Range: 12218-12229
Journal Issue: 34
DOI: 10.1021/ja9024269
Abstract
The synthesis of a new series of electron donor-acceptor conjugates (5, 10, 13, and 16) in which the electron acceptor - C - and the electron donor - π-extended tetrathiafulvalene (exTTF) - are bridged by means of m-phenyleneethynylene spacers of variable length is reported. The unexpected self-association of these hybrids was first detected to occur in the gas phase by means of MALDI-TOF spectrometry and subsequently corroborated in solution by utilizing concentration-dependent and variable-temperature H NMR experiments. Furthermore, the ability of these new conjugates to form wirelike structures upon deposition onto a mica surface has been demonstrated by AFM spectroscopy. In light of their photoactivity and redoxactivity, 5, 10, 13, and 16 were probed in concentration-dependent photophysical experiments. Importantly, absorption and fluorescence revealed subtle dissimilarities for the association constants, that is, a dependence on the length of the m-phenylene spacers. The binding strength is in 5 greatly reduced when compared with those in 10, 13, and 16. Not only that, the spacer length also plays a decisive role in governing excited-state interactions in the corresponding electron donor-acceptor conjugates (5, 10, 13, and 16). To this end, 5, in which the photo- and electroactive constituents are bridged by just one aromatic ring, displayssexclusively and independent of the concentration (10 to 10 M) - efficient intramolecular electron transfer events on the basis of a "through-bond" mechanism. On the contrary, the lack of conjugation throughout the bridges in 10 (two m-phenyleneethynylene rings), 13 (three m-phenyleneethynylene rings), and 16 (four m-phenyleneethynylene rings) favors at low concentration (10 M) "through space" intramolecular electron transfer events. These are, however, quite ineffective and, in turn, lead to excited-state deactivations that are at high concentrations (10 M) dominated by intracomplex electron transfer events, namely, between exTTF of one molecule and C of another molecule, and that stabilize the resulting radical ion pair state with lifetimes reaching 4.0 μs. © 2009 American Chemical Society.
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APA:
Molina-Ontoria, A., Fernandez, G., Wielopolski, M., Atienza, C., Sanchez, L., Gouloumis, A.,... Guldi, D.M. (2009). Self-association and electron transfer in donor-acceptor dyads connected by meta-substituted oligomers. Journal of the American Chemical Society, 131(34), 12218-12229. https://dx.doi.org/10.1021/ja9024269
MLA:
Molina-Ontoria, Agustin, et al. "Self-association and electron transfer in donor-acceptor dyads connected by meta-substituted oligomers." Journal of the American Chemical Society 131.34 (2009): 12218-12229.
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