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  Ultrafast Intersystem Crossing and Spin Dynamics of Photoexcited Perylene-3,4:9,10-bis(dicarboximide) Covalently Linked to a Nitroxide Radical at Fixed Distances

Giacobbe, E. M., Mi, Q., Colvin, M. T., Cohen, B., Ramanan, C., Scott, A. M., et al. (2009). Ultrafast Intersystem Crossing and Spin Dynamics of Photoexcited Perylene-3,4:9,10-bis(dicarboximide) Covalently Linked to a Nitroxide Radical at Fixed Distances. Journal of the American Chemical Society, 131(10), 3700-3712. doi:10.1021/ja808924f.

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Item Permalink: http://hdl.handle.net/21.11116/0000-0005-49DF-F Version Permalink: http://hdl.handle.net/21.11116/0000-0005-49E0-C
Genre: Journal Article

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 Creators:
Giacobbe, Emilie M., Author
Mi, Qixi, Author
Colvin, Michael T., Author
Cohen, Boiko, Author
Ramanan, Charusheela1, Author              
Scott, Amy M., Author
Yeganeh, Sina, Author
Marks, Tobin J., Author
Ratner, Mark A., Author
Wasielewski, Michael R., Author
Affiliations:
1Department of Chemistry, Argonne-Northwestern Solar Energy Research (ANSER) Center, and International Institute for Nanotechnology, Northwestern University, Evanston, Illinois, ou_persistent22              

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Free keywords: 10-perylenetetracarboxylic dianhydride dyes,3,4,9,bridge-acceptor molecules,electron-paramagnetic-resonance,excited singlet-states,intramolecular charge-transfer,quintet s=2 states,stable free-radicals,time-resolved epr,transient absorption-spectra,triplet-doublet interaction
 Abstract: Time-resolved transient optical absorption and EPR (TREPR) spectroscopies are used to probe the interaction of the lowest excited singlet state of perylene-3,4:9,10-bis(dicarboximide) ((1)*PDI) with a stable tert-butylphenylnitroxide radical ((BPNO)-B-2*) at specific distances and orientations. The (BPNO)-B-2* radical is connected to the PDI with the nitroxide and imide nitrogen atoms either para (1) or meta (3) to one another, as well as through a second intervening p-phenylene spacer (2). Transient absorption experiments on 1-3 reveal that (1)*PDI undergoes ultrafast enhanced intersystem crossing and internal conversion with, tau congruent to 2 ps to give structurally dependent 8-31% yields of (3)*PDI. Energy- and electron-transfer quenching of (1)*PDI by (BPNO)-B-2* are excluded on energetic and spectroscopic grounds. TREPR experiments at high magnetic fields (3.4 T, 94 GHz) show that the photogenerated three-spin system consists of the strongly coupled unpaired electrons confined to (3)*PDI, which are each weakly coupled to the unpaired electron on (BPNO)-B-2* to form excited doublet (D-1) and quartet (Q) states, which are both spectrally resolved from the (BPNO)-B-2* (D-0) ground state. The initial spin polarizations of D-1 and Q are emissive for 1 and 2 and absorptive for 3, which evolve over time to the opposite spin polarization. The subsequent decays of D-1 and Q to ground-state spin polarize D-0. The rates of polarization transfer depend on the molecular connectivity between PDI and (BPNO)-B-2* and can be rationalized in terms of the dependence on molecular structure of the through-bond electronic coupling between these species.

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Language(s): eng - English
 Dates: 20092009
 Publication Status: Published in print
 Pages: -
 Publishing info: -
 Table of Contents: -
 Rev. Method: -
 Identifiers: DOI: 10.1021/ja808924f
 Degree: -

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Title: Journal of the American Chemical Society
  Other : J. Am. Chem. Soc.
  Abbreviation : JACS
Source Genre: Journal
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Affiliations:
Publ. Info: Washington, DC : American Chemical Society
Pages: - Volume / Issue: 131 (10) Sequence Number: - Start / End Page: 3700 - 3712 Identifier: ISSN: 0002-7863
CoNE: https://pure.mpg.de/cone/journals/resource/954925376870