One-pot three-component polymerization for in situ generation of AIE-active poly(tetraarylethene)s using Grignard reagents as building blocks

Abstract

The development of efficient multi-component polymerizations from handy monomers to synthesize multifunctional polymers with complicated structures is an attractive but challenging research topic. In this work, a facile, one-pot, three-component polymerization route for in situ generation of polymers with aggregation-induced emission (AIE) characteristics has been developed. Under the catalysis of NiCl₂, polycoupling of dihaloarenes, internal diynes, and Grignard reagents proceeded efficiently, generating poly(tetraarylethene)s (PTAEs) with high number average molecular weights (M_n up to 16 800) in high yields (up to 93%) in only three hours. The obtained PTAEs show typical AIE characteristics due to the in situ-generated AIEgen units, tetraphenylethene, in the polymer backbone. Utilizing the AIE property, aggregate-state PTAE could serve as an efficient fluorescent chemosensor for picric acid and Ru³⁺ with amplified sensitivity, and the quenching constants reached 2.33 × 10⁶ L mol⁻¹ and 6.85 × 10⁴ L mol⁻¹, respectively. Furthermore, the polymer thin films showed modulable refractive indices under UV irradiation in the wide wavelength region of 400–900 nm, presenting great potential in optical fiber applications. Well-resolved 2D fluorescent patterns can also be generated by photo-oxidation of the thin films of PTAEs under UV irradiation through a copper photomask. This work provides another successful example of an in situ generation strategy for functional AIE polymers, broadening the scope of the monomer library.