Approaches for synthesis of soluble poly(3,6‐dihydroxy‐2,7‐carbazole) with phenolic function

Poly(N‐alkyl‐3,6‐dihydroxy‐2,7‐carbazole) which should be soluble and have phenolic function was synthesized through different two routes. The former method was a direct synthesis by polymerizing a 2,7‐dibromo‐3,6‐dihydroxycarbazole monomer using Ni(cod)₂, which only gave a low molecular weight polymer. The latter method was an ether cleavage reaction of methoxy groups in a precursor polymer, poly(3,6‐dimethoxycarbazole), using BBr₃, which gave successfully the objective polymer that has a number average molecular weight of 4300 g/mol comparable to the precursor polymer. They showed large spectral changes in photoabsorption and fluorescence on addition of base. They also showed redox behavior similar to a hydroquinone/benzoquinone couple investigated by cyclic voltammetry. These new functions could be derived from the phenolic hydroxy group in the carbazole unit. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 2039–2044