A nonconjugated AIE polymer from enol-conjugated ACQ curcumin through nucleophilic substitution polymerization-induced emission towards enhanced photocatalytic hydrogen evolution

Abstract

Aggregation-induced emission (AIE) polymers have gained considerable research efforts, and are mostly prepared by incorporating conjugated AIE moieties into polymer chains and suffer from a multi-step synthetic procedure. Here, a one-pot polymerization-induced emission (PIE) approach is demonstrated as a versatile method for synthesizing a nonconjugated AIE polymer, through nucleophilic substitution polymerization (S_NP) of curcumin and 1,3-bis(bromomethyl)benzene. Interestingly, an aggregation-caused quenching (ACQ)-to-AIE transformation is achieved during this S_NPIE, where conjugated and ACQ curcumin transforms into a nonconjugated and AIE polymer. This ACQ-to-AIE transformation might expand the library of AIE polymers, by taking advantage of widespread conjugated ACQ moieties. Further photocatalytic applications of the obtained AIE polymer were carried out, and it exhibited highly efficient activity with an optimal H₂ production rate of 3122.5 μmol g⁻¹ h⁻¹ under visible-light irradiation through a ligand–metal charge transfer (LMCT) between the curcumin-containing AIE polymer and titanium dioxide. This work therefore might be inspirational in materials science, H₂ evolution, polymer chemistry, photocatalysis, AIE and PIE.