TY - JOUR
T1 - Competition between Singlet Fission and Spin-Orbit-Induced Intersystem Crossing in Anthanthrene and Anthanthrone Derivatives
AU - Jue Bae, Youn
AU - Krzyaniak, Matthew D.
AU - Majewski, Marek B.
AU - Desroches, Maude
AU - Morin, Jean François
AU - Wu, Yi Lin
AU - Wasielewski, Michael R.
N1 - Funding Information:
This work was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award DE‐FG02‐99ER14999 (M.R.W.). This work made use of the IMSERC at Northwestern University, which has received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS‐1542205), the State of Illinois, and the International Institute for Nanotechnology (IIN). Y.B. thanks Charlotte Stern for helpful discussions regarding X‐ray work. M.B.M. acknowledges support from the Natural Sciences and Engineering Research Council of Canada and Fonds de recherche du Québec – Nature et technologies.
Funding Information:
This work was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award DE-FG02-99ER14999 (M.R.W.). This work made use of the IMSERC at Northwestern University, which has received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS-1542205), the State of Illinois, and the International Institute for Nanotechnology (IIN). Y.B. thanks Charlotte Stern for helpful discussions regarding X-ray work. M.B.M. acknowledges support from the Natural Sciences and Engineering Research Council of Canada and Fonds de recherche du Qu?bec ? Nature et technologies.
Publisher Copyright:
© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
PY - 2019/9/1
Y1 - 2019/9/1
N2 - Singlet and triplet excited-state dynamics of anthanthrene and anthanthrone derivatives in solution are studied. Triisopropylsilyl- (TIPS) or H-terminated ethynyl groups are used to tune the singlet and triplet energies to enable their potential applications in singlet fission and triplet fusion processes. Time-resolved optical and electron paramagnetic resonance (EPR) spectroscopies are used to obtain a mechanistic understanding of triplet formation. The anthanthrene derivatives form triplet states efficiently at a rate (ca. 107 s−1) comparable to radiative singlet fluorescence processes with approximately 30 % triplet yields, despite their large S1-T1 energy gap (>1 eV) and the lack of carbonyl groups. In contrast, anthanthrone has a higher triplet yield (50±10 %) with a faster intersystem crossing rate (2.7 * 108 s−1) because of the n-π* character of the S1←S0 transition. Analysis of time-resolved spin-polarized EPR spectra of these compounds reveals that the triplet states are primarily generated by the spin-orbit-induced intersystem crossing mechanism. However, at high concentrations, the EPR spectrum of the 4,6,10,14-tetrakis(TIPS-ethynyl)anthanthrene triplet state shows a significant contribution from a non-Boltzmann population of the ms=0 spin sublevel, which is characteristic of triplet formation by singlet fission.
AB - Singlet and triplet excited-state dynamics of anthanthrene and anthanthrone derivatives in solution are studied. Triisopropylsilyl- (TIPS) or H-terminated ethynyl groups are used to tune the singlet and triplet energies to enable their potential applications in singlet fission and triplet fusion processes. Time-resolved optical and electron paramagnetic resonance (EPR) spectroscopies are used to obtain a mechanistic understanding of triplet formation. The anthanthrene derivatives form triplet states efficiently at a rate (ca. 107 s−1) comparable to radiative singlet fluorescence processes with approximately 30 % triplet yields, despite their large S1-T1 energy gap (>1 eV) and the lack of carbonyl groups. In contrast, anthanthrone has a higher triplet yield (50±10 %) with a faster intersystem crossing rate (2.7 * 108 s−1) because of the n-π* character of the S1←S0 transition. Analysis of time-resolved spin-polarized EPR spectra of these compounds reveals that the triplet states are primarily generated by the spin-orbit-induced intersystem crossing mechanism. However, at high concentrations, the EPR spectrum of the 4,6,10,14-tetrakis(TIPS-ethynyl)anthanthrene triplet state shows a significant contribution from a non-Boltzmann population of the ms=0 spin sublevel, which is characteristic of triplet formation by singlet fission.
KW - anthanthrene
KW - anthanthrone
KW - photochemistry
KW - singlet fission
KW - spin-orbit intersystem crossing
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U2 - 10.1002/cplu.201900410
DO - 10.1002/cplu.201900410
M3 - Article
C2 - 31944060
AN - SCOPUS:85070863254
VL - 84
SP - 1432
EP - 1438
JO - ChemPlusChem
JF - ChemPlusChem
SN - 2192-6506
IS - 9
ER -