Large Dipolar Spin - Spin Interaction in a Photogenerated U-Shaped Triradical

Daniel M. Gardner, Hsiao Fan Chen, Matthew D. Krzyaniak, Mark A. Ratner, Michael R. Wasielewski*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


Transient electron paramagnetic resonance (TREPR) spectroscopy has been used to study the spin - spin interactions in a novel U-shaped electron donor - chromophore - acceptor - radical (D - C - A - R) system in which a xanthene bridge holds a tert-butylphenyl nitroxide (BPNO) radical in close proximity to a naphthalene-1,8:4,5-bis(dicarboximide) (NDI) acceptor. Photoexcitation of the 4-aminonaphthalene-1,8-dicarboximide (ANI) chromophore results in rapid, two-step electron transfer to generate the triradical (D+• - C - A-• - R). The large through-bond distance between A-• and R makes their spin - spin exchange interaction (2JAR) negligibly small, whereas their short through-space distance results in a strong dipolar interaction (DAR), which is observed as a set of broad lines in the TREPR spectra of D+• - C - A-• - R in solid toluene solution at 85 K. Transient nutation experiments show that these transitions belong to a species with spin S = 1, whereas experiments on D+• - C - A-• - R in the oriented nematic liquid crystal 4-cyano-4′-n-pentylbiphenyl at 85 K demonstrate the anisotropy of DAR. (Figure Presented)

Original languageEnglish (US)
Pages (from-to)8040-8048
Number of pages9
JournalJournal of Physical Chemistry A
Issue number29
StatePublished - Jul 23 2015

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry


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