期刊
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
卷 135, 期 28, 页码 10372-10381出版社
AMER CHEMICAL SOC
DOI: 10.1021/ja401239r
关键词
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资金
- MINECO of Spain [CTQ2011-24652, PIB2010JP-00196, 2010C-07-25200, Consolider-IngenioCSD2007-00010]
- FUNMOLS [FP7-212942-1]
- MOLESCO
- CAM [MADRISOLAR-2 S2009/PPQ-1533]
- MEC of Spain
- Ramon y Cajal contract
- Beilstein Foundation Scholarship
A series of ZnP-pCp-oPPV-C-60 conjugates covalently connected through [2,2']-paracyclophane-oligophenylenevinylene (pCp-oPPV) bridges containing one, two, and three [2,2']-paracyclophanes (pCps) has been prepared in multistep synthetic procedures involving Horner-Wadsworth-Emmons olefination reactions and/or Heck type Pd-catalyzed reactions. Molecular modeling suggests that charge transfer is effectively mediated by the pCp-oPPVs through a predominant hole-transfer mechanism. Photophysical investigation supports molecular modeling and reveals two major trends. On one hand, C-60 excitation of 1, 2, and 3 leads exclusively to charge transfer between pCp and C-60 to afford a ZnP-(pCp-oPPV)(circle+)-C-60(circle-) radical ion pair state without giving rise to a subsequent charge shift to yield the ZnP circle+-pCp-oPPV-C-60(circle-) radical ion pair state. On the other hand, ZnP excitation of 1, 2, and 3 results in a rather slow charge transfer between ZnP and C-60, after which the ZnP circle+-pCp-oPPV-C-60(circle-) radical ion pair state evolves. In temperature-dependent ZnP fluorescence experiments, which were performed in the temperature range from 273 to 338 K, two domains are discernible: low and high temperature behaviors. In the low temperature range (i.e., below 30 degrees C) the rate constants do not change, suggesting that a superexchange mechanism is the modus operandi. In the high temperature range (i.e., >30 degrees C) the rate constants increase. Moreover, we find rather strong distance dependence for 1 and 2 and weak distance dependence for 2 and 3. A damping factor of 0.145 angstrom(-1) is derived for the former pair and 0.012 angstrom(-1) for the latter.
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