Electron‐Deficient Bipyrrole Boomerangs: Bright Fluorophores Obtained via Double C−H Bond Activation

PdII‐mediated annulative double C−H activation is shown to efficiently convert 1,n‐dipyrrolylalkanes into extensively π‐conjugated bipyrroles not accessible by conventional oxidative coupling protocols. This approach is applicable to both electron‐rich and electron‐deficient systems, and has been fu...

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Bibliographic Details
Published in:Chemistry : a European journal 2018-05, Vol.24 (29), p.7525-7530
Main Authors: Żyła‐Karwowska, Marika, Moshniaha, Liliia, Hong, Yongseok, Zhylitskaya, Halina, Cybińska, Joanna, Chmielewski, Piotr J., Lis, Tadeusz, Kim, Dongho, Stępień, Marcin
Format: Article
Language:English
Subjects:
Activation
Charge transfer
Chemical compounds
Chemistry
Chromophores
C−H activation
Electrons
Fluorescence
Fluorophores
helical structures
heterocycles
Intermediates
Optical properties
Oxygenation
Polarity
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Summary:PdII‐mediated annulative double C−H activation is shown to efficiently convert 1,n‐dipyrrolylalkanes into extensively π‐conjugated bipyrroles not accessible by conventional oxidative coupling protocols. This approach is applicable to both electron‐rich and electron‐deficient systems, and has been further developed into tandem processes involving further cyclization of substituents or oxygenation of pyrrolic α‐positions. The new bipyrrole intermediates show enhanced fluorescence as well as tunable optical properties controlled by the alignment of chromophore subunits. Photophysical data, including femtosecond transient absorptions, reveal solvent‐induced intramolecular charge transfer in their excited states, dependent on the polarity of the medium. Break it with a boomerang! A new family of aromatic molecules with a distinct boomerang shape (see graphic) has been developed through annulative double C−H bond activation. This chemistry provides access to boomerangs with variable bends and twists, and tunable donor–acceptor properties. These new chromophores fluoresce strongly in solvents of varying polarity and undergo photoinduced intramolecular charge transfer in the excited state.
ISSN:0947-6539
1521-3765
DOI:10.1002/chem.201801199