Solution-based intramolecular singlet fission in cross-conjugated pentacene dimers.
We show unambiguous and compelling evidence by means of pump-probe experiments, which are complemented by calculations using ab initio multireference perturbation theory, for intramolecular singlet fission (SF) within two synthetically tailored pentacene dimers with cross-conjugation, namely XC1 and XC2. The two pentacene dimers differ in terms of electronic interactions as evidenced by perturbation of the ground state absorption spectra stemming from stronger through-bond contributions in XC1 as confirmed by theory. Multiwavelength analysis, on one hand, and global analysis, on the other hand, confirm that the rapid singlet excited state decay and triplet excited state growth relate to SF. SF rate constants and quantum yields increase with solvent polarity. For example, XC2 reveals triplet quantum yields and rate constants as high as 162 ± 10% and (0.7 ± 0.1) × 10(12) s(-1), respectively, in room temperature solutions.
Department of Chemistry and Pharmacy & Interdisciplinary Center for Molecular Materials (ICMM), Engineering of Advanced Materials (EAM), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Egerlandstrasse 3, 91058 Erlangen, Germany. dirk.guldi@fau.de.
Johannes
J
Zirzlmeier
Rubén
R
Casillas
S Rajagopala
SR
Reddy
Pedro B
PB
Coto
Dan
D
Lehnherr
Erin T
ET
Chernick
Ilias
I
Papadopoulos
Michael
M
Thoss
Rik R
RR
Tykwinski
Dirk M
DM
Guldi