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.
Bibliographical noteFunding Information:
Financial support from the National Science Center of Poland (UMO-2014/13/B/ST5/04394, UMO-2015/19/N/ST5/00877) is gratefully acknowledged. Quantum chemical calculations were performed at the Wrocław Center for Networking and Supercomputing. The work at Yonsei University was supported by Strategic Research (NRF-2016R1E1A1A01943379) through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT (Information and Communication Technologies) and Future Planning.
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All Science Journal Classification (ASJC) codes
- Organic Chemistry