A prototype of benzobis(imidazolium)-embedded conjugated polyelectrolyte: Synthesis by direct C‒H arylation and fluorescent responses to anions

We report the convenient synthesis of a benzobis(imidazolium)-embedded conjugated polyelectrolyte pBBI by a Cu-catalyzed direct C‒H arylation of a cationic benzobis(imidazolium) monomer with a diiodide comonomer. pBBI shows weak fluorescence in solution due to rotation of the repeat units in the conjugated backbone, and enhanced fluorescence when electrostatically interacting with a variety of anions to form aggregates. Specially, pBBI responds to the bisulfite anion with intensified unique deep-blue fluorescence easily discriminated by naked eye. A Cu-catalyzed C–H polymerization protocol is developed to synthesize a prototype of cationic benzobis(imidazolium)-embedded conjugated polyelectrolyte pBBI. It responds to the bisulfite anion with intensified unique deep blue-colored fluorescence, in contrast to the well-known amplified fluorescence quenching behaviors of side-chain CPEs. [Display omitted]