Synthesis and Characterizations of 5,5'-Bibenzo[rst]pentaphene with Axial Chirality and Symmetry-Breaking Charge Transfer.
Xiushang XuSuman GunasekaranScott RenkenLorenzo RipaniDieter SchollmeyerWoojae KimMassimo MarcaccioAndrew MusserAkimitsu NaritaPublished in: Advanced science (Weinheim, Baden-Wurttemberg, Germany) (2022)
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 S 1 electronic state that is enabled by Herzberg-Teller intensity borrowing from a neighboring bright S 2 state. While BPP exhibits a relatively low photoluminescence quantum yield (PLQY), BBPP exhibits a significantly enhanced PLQY due to a greater S 2 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.
Keyphrases
- single molecule
- high performance liquid chromatography
- density functional theory
- high resolution
- energy transfer
- molecular dynamics
- mass spectrometry
- capillary electrophoresis
- tandem mass spectrometry
- high intensity
- solid state
- simultaneous determination
- solid phase extraction
- ionic liquid
- quantum dots
- molecular docking
- molecularly imprinted
- liquid chromatography
- magnetic resonance
- human health
- brain injury
- climate change
- blood brain barrier