Synthesis, characterization, aggregation-induced emission and nanoaggregates of the copolymers containing different ratios of carbazoles and tetraphenylethylenes

Abstract

In this work, polymers comprising of the different ratios of N-decyl or N-triethylene glycol substituted 2,7-carbazoles and tetraphenylethenes were designed and synthesized by palladium-catalyzed Suzuki Miyaura cross-coupling reaction of their corresponding comonomers. The copolymers containing carbazoles and tetraphenylethenes showed aggregation induced emission characteristics in both solid state and aggregate state when the composition of the tetraphenylethenes reached to 50%. N-triethylene glycol substituted carbazole polymers revealed lower bandgap and higher HOMO level compared to that of the N-decyl substituted carbazole polymers. The higher composition of the tetraphenylethenes, the deeper HOMO level and the larger bandgap of the polymers. Polymers with 1:1 molar ratio of the carbazoles and the tetraphenylethenes exhibited sphere-like nanoparticles with an average diameter of around 30 nm. The polymers containing carbazole and TPE units in 3:1 or 1:3 molar ratio self-assembled to form nanoaggregates with a size of around 100 nm.