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

Advanced Science

Andrew Musser¹  Woojae Kim¹  Suman Gunasekaran¹  Scott Renken¹  Dieter Schollmeyer²  Massimo Marcaccio³  Lorenzo Ripani³  Xiushang Xu⁴  Akimitsu Narita⁴ 

[1] Department of Chemistry & Chemical Biology Cornell University Ithaca NY 14853 USA;Department of Chemistry Johannes Gutenberg University Mainz Duesbergweg 10–14 Mainz 55128 Germany;Dipartimento di Chimica “Giacomo Ciamician” Università di Bologna via Selmi 2 Bologna 40126 Italy;Max Planck Institute for Polymer Research Ackermannweg 10 Mainz 55128 Germany;

关键词: axial chirality;    benzo[rst]pentaphene;    biaryl;    symmetry‐breaking charge transfer;    transient absorption;   

DOI  :  10.1002/advs.202200004

来源: DOAJ

【 摘 要 】

Abstract 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.

【 授权许可】

Unknown