Synthesis, optical, and electrochemical properties of the high-molecular-weight conjugated polycarbazoles

A kind of novel dibromocarbazole monomer hearing three alkyl chains was prepared. Two strategies were developed to improve the solubility molecular weight of carbazole polymers. One was the polymerization of N-octyl-2,7-bis(4,4,5,5-tetramethyl- 1,3,2-dioxaborolan-2-yl)carbazole with the alkylated dibromocarbazole. Another one was the polymerization of N-octyl-2,7-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl.)carbazole with N-octyl-3,6-dibromocarbazole. All the polymerizations were carried Out under palladium-catalyzed Suzuki polycondensation (SPC) conditions. Through using carbazole monomer hearing three alkyl chains to polymerize, we have successfully boosted the number-average molecular weight of 2,7-linked carbazole polymers from not more than 5 to 67 kDa. The high-molecular-weight polymers were obtained in high yields and displayed good solubility in common organic solvents. Their optical, electrochemical, and thermal properties were also reported.