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Indeno[1,2‐ b ]fluorene‐Based [2,2]Cyclophanes with 4 n /4 n and 4 n /[4 n +2] π Electrons: Syntheses, Structural Analyses, and Excitonic Coupling Properties
Author(s) -
Wang ChiShin,
Wei YuChen,
Chang KaiHsin,
Chou PiTai,
Wu YaoTing
Publication year - 2019
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201903561
Subject(s) - fluorene , chemistry , excited state , ultrafast laser spectroscopy , crystallography , superexchange , monomer , absorption spectroscopy , spectroscopy , photochemistry , absorption (acoustics) , stereochemistry , materials science , atomic physics , physics , ion , polymer , organic chemistry , quantum mechanics , composite material
Indeno[1,2‐ b ]fluorene‐based [2,2]cyclophanes with 4 n /4 n and 4 n /[4 n +2] π‐electron systems were prepared, and their structures were identified by X‐ray crystallography. With short π–π distances around 3.0 Å, [2.2](5,11)indeno[1,2‐ b ]fluorenophane and its precursor [2.2](5,11)indeno[1,2‐ b ]fluorene‐6,12‐dionophane exhibit remarkable transannular interactions, leading to their unusual electrochemical and photophysical properties. With the aid of femtosecond transient absorption spectroscopy, the transition from the monomeric excited state to the redshifted H‐type dimeric state was first observed, correlating to the calculated excitonic energy splitting and the steady‐state absorption spectra induced by charge‐transfer‐mediated superexchange interaction.