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Fast Triplet Formation via Singlet Exciton Fission in a Covalent Perylenediimide-ß-apocarotene Dyad Aggregate.
Mauck, Catherine M; Brown, Kristen E; Horwitz, Noah E; Wasielewski, Michael R.
Afiliação
  • Mauck CM; Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, 2145 North Sheridan Road, Evanston, Illinois 60208-3113, United States.
  • Brown KE; Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, 2145 North Sheridan Road, Evanston, Illinois 60208-3113, United States.
  • Horwitz NE; Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, 2145 North Sheridan Road, Evanston, Illinois 60208-3113, United States.
  • Wasielewski MR; Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, 2145 North Sheridan Road, Evanston, Illinois 60208-3113, United States.
J Phys Chem A ; 119(22): 5587-96, 2015 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-25961130
ABSTRACT
A covalent dyad was synthesized in which perylene-3,4,910-bis(dicarboximide) (PDI) is linked to ß-apocarotene (Car) using a biphenyl spacer. The dyad is monomeric in toluene and forms a solution aggregate in methylcyclohexane (MCH). Using femtosecond transient absorption (fsTA) spectroscopy, the monomeric dyad and its aggregates were studied both in solution and in thin films. In toluene, photoexcitation at 530 nm preferentially excites PDI, and the dyad undergoes charge separation in τ = 1.7 ps and recombination in τ = 1.6 ns. In MCH and in thin solid films, 530 nm excitation of the PDI-Car aggregate also results in charge transfer that competes with energy transfer from (1)*PDI to Car and with an additional process, rapid Car triplet formation in <50 ps. Car triplet formation is only observed in the aggregated PDI-Car dyad and is attributed to singlet exciton fission (SF) within the aggregated PDI, followed by rapid triplet energy transfer from (3)*PDI to the carotenoid. SF from ß-apocarotene aggregation is ruled out by direct excitation of Car films at 414 nm, where no triplet formation is observed. Time-resolved electron paramagnetic resonance measurements on aggregated PDI-Car show the formation of (3)*Car with a spin-polarization pattern that rules out radical-pair intersystem crossing as the mechanism of triplet formation as well.

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Texto completo: Disponível Coleções: Bases de dados internacionais Base de dados: MEDLINE Idioma: Inglês Revista: J Phys Chem A Assunto da revista: Química Ano de publicação: 2015 Tipo de documento: Artigo País de afiliação: Estados Unidos