Influence of Intermolecular Orientation on the Photoinduced Charge Transfer Kinetics in Self-Assembled Aggregates of Donor-Acceptor Arrays

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• 作者：Edwin H. A. Beckers ; Stefan C. J. Meskers ; Albertus P. H. J. Schenning ; Zhijian Chen ; Frank Wü ; rthner ; Philippe Marsal ; David Beljonne ; J&eacute ; rô ; me Cornil ; and Ren&eacute ; A. J. Janssen
• 刊名：Journal of the American Chemical Society
• 出版年：2006
• 出版时间：January 18, 2006
• 年：2006
• 卷：128
• 期：2
• 页码：649 - 657
• 全文大小：232K
• 年卷期：v.128,no.2(January 18, 2006)
• ISSN：1520-5126

文摘

The kinetics of photoinduced charge transfer reactions in covalently linked donor-acceptormolecules often undergoes dramatic changes when these molecules self-assemble from a moleculardissolved state into a nanoaggregate. Frequently, the origin of these changes is only partially understood.In this paper, we describe the intermolecular spatial organization of three homologous arrays, consistingof a central perylene bisimide (PERY) acceptor moiety and two oligo(p-phenylene vinylene) (OPV) donorunits, in nanoaggregates and identify both face-to-face (H-type) and slipped (J-type) stacking of the OPVand PERY chromophores. For the J-type aggregates, short intermolecular OPV-PERY distances arecreated that give rise to a charge-transfer absorption band. The proximity of the donor and acceptor groupsin the J-type aggregates enables a highly efficient photoinduced charge separation with a rate (k_cs > 10¹²s^-1) that significantly exceeds the rate of the intramolecular charge transfer of the same compounds whenmolecularly dissolved, even in the most polar media. In the H-type aggregates, on the other hand, theintermolecular OPV-PERY distance is not reduced compared to the intramolecular separation, and hence,the rates of the electron transfer reactions are not significantly affected compared to the molecular dissolvedstate. Similar to the forward electron transfer, the kinetics of the charge recombination in the aggregatedstate can be understood by considering the different interchromophoric distances that occur in the H- andJ-type aggregates. These results provide the first consistent rationalization of the remarkable differencesthat are observed for photoinduced charge-transfer reactions of donor-acceptor compounds in molecularlydissolved versus aggregated states.