Conformational Planarization versus Singlet Fission: Distinct Excited-State Dynamics of Cyclooctatetraene-Fused Acene Dimers

Takuya Yamakado; Shota Takahashi; Kazuya Watanabe; Yoshiyasu Matsumoto; Atsuhiro Osuka; Shohei Saito

doi:10.1002/anie.201802185

Conformational Planarization versus Singlet Fission: Distinct Excited-State Dynamics of Cyclooctatetraene-Fused Acene Dimers

Angew Chem Int Ed Engl. 2018 May 4;57(19):5438-5443. doi: 10.1002/anie.201802185. Epub 2018 Mar 30.

Authors

Takuya Yamakado¹, Shota Takahashi¹, Kazuya Watanabe¹, Yoshiyasu Matsumoto¹, Atsuhiro Osuka¹, Shohei Saito^{1

2}

Affiliations

¹ Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan.
² JST-PRESTO, FRONTIER, Japan.

PMID: 29516597
DOI: 10.1002/anie.201802185

Abstract

A set of flapping acene dimers fused with an 8π cyclooctatetraene (COT) ring showed distinct excited-state dynamics in solution. While the anthracene dimer showed a fast V-shaped-to-planar conformational change within 10 ps in the lowest excited singlet state, reminding us of extended Baird aromaticity, the tetracene dimer and the pentacene dimer underwent intramolecular singlet fission (SF) in different manners: A fast and reversible SF with a characteristic delayed fluorescence (FL), and a fast and quantitative SF, respectively. Conformational flexibility of the fused COT linkage plays an important role in these ultrafast dynamics, demonstrating the utility of the flapping molecular series as a versatile platform for designing photofunctional systems.

Keywords: Baird aromaticity; acenes; cyclooctatetraene; excited-state dynamics; singlet fission.

Publication types

Research Support, Non-U.S. Gov't