Synthesis and Characterizations of 5,5′-Bibenzo[rst]pentaphene with Axial Chirality and Symmetry-Breaking Charge Transfer

Xiushang Xu, Suman Gunasekaran, Scott Renken, Lorenzo Ripani, Dieter Schollmeyer, Woojae Kim, Massimo Marcaccio, Andrew Musser, Akimitsu Narita

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4 Citations (Scopus)


Exploration of novel biaryls consisting of two polycyclic aromatic hydrocarbon (PAH) units can be an important strategy toward further developments of organic materials with unique properties. In this study, 5,5′-bibenzo[rst]pentaphene (BBPP) with two benzo[rst]pentaphene (BPP) units is synthesized in an efficient and versatile approach, and its structure is unambiguously elucidated by X-ray crystallography. BBPP exhibits axial chirality, and the (M)- and (P)-enantiomers are resolved by chiral high-performance liquid chromatography and studied by circular dichroism spectroscopy. These enantiomers have a relatively high isomerization barrier of 43.6 kcal mol−1 calculated by density functional theory. The monomer BPP and dimer BBPP are characterized by UV-vis absorption and fluorescence spectroscopy, cyclic voltammetry, and femtosecond transient absorption spectroscopy. The results indicate that both BPP and BBPP fluoresce from a formally dark S1 electronic state that is enabled by Herzberg–Teller intensity borrowing from a neighboring bright S2 state. While BPP exhibits a relatively low photoluminescence quantum yield (PLQY), BBPP exhibits a significantly enhanced PLQY due to a greater S2 intensity borrowing. Moreover, symmetry-breaking charge transfer in BBPP is demonstrated by spectroscopic investigations in solvents of different polarity. This suggests high potential for singlet fission in such π-extended biaryls through appropriate molecular design.

Original languageEnglish
Article number2200004
JournalAdvanced Science
Issue number19
Publication statusPublished - 2022 Jul 6

Bibliographical note

Publisher Copyright:
© 2022 The Authors. Advanced Science published by Wiley-VCH GmbH.

All Science Journal Classification (ASJC) codes

  • Medicine (miscellaneous)
  • General Chemical Engineering
  • General Materials Science
  • Biochemistry, Genetics and Molecular Biology (miscellaneous)
  • General Engineering
  • General Physics and Astronomy


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