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Shape-Selective Synthesis of Pentacene Macrocycles and the Effect of Geometry on Singlet Fission

preprint
revised on 19.09.2020 and posted on 21.09.2020 by Harrison Bergman, Gavin Kiel, Ryan J. Witzke, David P. Nenon, Adam M. Schwartzberg, Yi Liu, T. Don Tilley

Pentacene’s extraordinary photophysical and electronic properties are highly dependent on intermolecular, through-space interactions. Macrocyclic arrangements of chromophores have been shown to provide a high level of control over these interactions, but few examples exist for pentacene due to inherent synthetic challenges. In this work, zirconocene-mediated alkyne coupling was used as a dynamic covalent C-C bond forming reaction to synthesize two geometrically distinct, pentacene-containing macrocycles on a gram scale and in four or fewer steps. Both macrocycles undergo singlet fission in solution, with rates that differ by an order of magnitude while the rate of triplet recombination is approximately the same. This independent modulation of singlet and triplet decay rates is highly desirable for the design of efficient singlet fission materials. The dimeric macrocycle adopts a columnar packing motif in the solid state, with large void spaces between pentacene units of the crystal lattice.

Funding

NSF CHE-1708210

History

Email Address of Submitting Author

harrison_bergman@berkeley.edu

Institution

UC Berkeley

Country

United States

ORCID For Submitting Author

0000-0001-6482-2837

Declaration of Conflict of Interest

None

Version Notes

Version 1.1

Exports