[60]fullerene bisadducts containing the C2ν-symmetrical 2,2,5,5-tetramethylpyrrolidine-1-oxyl moiety have been synthesized. Their EPR spectrum is typical of nitroxide biradicals with electron exchange interaction J of the same order of the nitrogen hyperfine coupling. From the EPR spectrum the absolute value of J was obtained, while the sign was measured by ENDOR. When the derivatives are photoexcited strong spin polarization is observed with A/E/A/E or E/A/E/A patterns, according to a positive or a negative sign of J. This behavior is accounted for by an intramolecular triplet–triplet interaction. The analogy with the polarization of transient spin correlated radical pairs is pointed out.

CIDEP of fullerene C-60 biradical bisadducts by intramolecular triplet-triplet quenching: a novel spin polarization mechanism for biradicals

CORVAJA, CARLO;FRANCO, LORENZO;MAZZONI, MARTINA;MAGGINI, MICHELE;MENNA, ENZO;SCORRANO, GIANFRANCO
2000

Abstract

[60]fullerene bisadducts containing the C2ν-symmetrical 2,2,5,5-tetramethylpyrrolidine-1-oxyl moiety have been synthesized. Their EPR spectrum is typical of nitroxide biradicals with electron exchange interaction J of the same order of the nitrogen hyperfine coupling. From the EPR spectrum the absolute value of J was obtained, while the sign was measured by ENDOR. When the derivatives are photoexcited strong spin polarization is observed with A/E/A/E or E/A/E/A patterns, according to a positive or a negative sign of J. This behavior is accounted for by an intramolecular triplet–triplet interaction. The analogy with the polarization of transient spin correlated radical pairs is pointed out.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11577/2458853
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