TY - JOUR
T1 - Large Dipolar Spin - Spin Interaction in a Photogenerated U-Shaped Triradical
AU - Gardner, Daniel M.
AU - Chen, Hsiao Fan
AU - Krzyaniak, Matthew D.
AU - Ratner, Mark A.
AU - Wasielewski, Michael R.
N1 - Publisher Copyright:
© 2015 American Chemical Society.
PY - 2015/7/23
Y1 - 2015/7/23
N2 - 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)
AB - 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)
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U2 - 10.1021/acs.jpca.5b03048
DO - 10.1021/acs.jpca.5b03048
M3 - Article
C2 - 26098409
AN - SCOPUS:84937889875
SN - 1089-5639
VL - 119
SP - 8040
EP - 8048
JO - Journal of Physical Chemistry A
JF - Journal of Physical Chemistry A
IS - 29
ER -