Syntheses of Anthracene-centered Large PAH Diimides and Conjugated Polymers

摘要:

Polycyclic aromatic hydrocarbon (PAH) structures with suitable electron-withdrawing groups are useful building blocks for developing optical and electron-transporting materials. Here, we report the application of double benzannulation processes to synthesize PAH diimides with enlarged π-frameworks featuring a central anthracene moiety. The processes are realized by copper-catalyzed [4+2] cycloaddition of ethynyl-substituted aromatic dicarobximide to 2,5-bis(phenylethynyl)terephthalaldehyde, followed by intramolecular photocyclization or direct arylation via Heck cross coupling. Specifically, A central symmetric benzo[1,2- k :4,5- k ']-bis(fluoranthene)-3,4,12,13-tetracarboxyl diimide (BFDI) is acquired, with a single crystal revealing its completely planar polycyclic skeleton. Such a shape-persistent PAH expectedly exhibits a tendency to stack face-to-face and forms J-aggregates. Moreover, BFDI can be expediently difunctionalized site-selectively in reactive 9 and 10 positions of the anthracene unit and applied to prepare conjugated polymers. When coupled with 1,4-diketopyrrolo[3,4- c ]-pyrrole (DPP) via thiophene and dithiophene linkers, two significantly broadened absorption bands extended to the near-infrared regime appear, evidencing the effective π-conjugative extension ability of BFDI unit.

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