Challenges in distinguishing superexchange and hopping mechanisms of intramolecular charge transfer through fluorene ligomers

  • Posted on: 10 July 2014
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TitleChallenges in distinguishing superexchange and hopping mechanisms of intramolecular charge transfer through fluorene ligomers
Publication TypeJournal Article
Year of Publication2008
AuthorsGoldsmith R.H, DeLeon O., Wilson T.M, Finkelstein-Shapiro D., Ratner M.A, Wasielewski M.R
JournalJournal of Physical Chemistry A
Volume112
Pagination4410-4414
Date PublishedMay 15
ISBN Number1089-5639
Accession NumberISI:000255649300002
Keywordsanomalous distance dependence, conjugated polymer, DNA, hole transfer, long-range, molecular-wire behavior, photoinduced electron-transfer, photosynthesis, transfer rates, transport
Abstract

The temperature dependence of intramolecular charge separation in a series of donor-bridge-acceptor molecules having phenothiazine (PTZ) donors, 2,7-oligofluorene FLn (n = 1-4) bridges, and perylene-3,4:9,10-bis(dicarboximide) (PDI) acceptors was studied. Photoexcitation of PDI to its lowest excited singlet state results in oxidation of PTZ via the FLn bridge. In toluene, the temperature dependence of the charge separation rate constants for PTZ-FLn-PDI, (n = 1-4) is relatively weak and is successfully described by the semiclassical Marcus equation. The activation energies for charge separation suggest that bridge charge carrier injection is not the rate limiting step. The difficulty of using temperature and length dependence to differentiate hopping and superexchange is discussed, with difficulties in the latter topic explored via an extension of a kinetic model proposed by Bixon and Jortner.

Alternate JournalJ Phys Chem A