One-Pot Barbier Polymerization-Induced Emission toward Stimuli-Responsive Luminescent Borinic Acid Polymers with Aggregation-Induced Emission-Type Clusteroluminescence

Abstract A stimuli-responsive luminescent polymer is a promising smart material, which, however, suffers from multiple synthetic procedures involving the general preparation of a stimuli-responsive moiety, a luminescent moiety, and a polymer chain. Here, a one-pot polymerization-induced emission strategy is demonstrated for the synthesis of a stimuli-responsive luminescent polymer. Through Barbier hyperbranching polymerization of 4,4’-dichlorobenzophenone in the presence of trimethyl borate in one pot, a borinic acid moiety is successfully incorporated into the polymer chain through carbon–boron bond formation. This modification endows the polymer with both stimuli-responsive and luminescent functionalities simultaneously, resulting in the preparation of a stimuli-responsive luminescent polymer in one pot. In comparison with borinic acid polymers with an aggregation-caused quenching effect reported in the literature, borinic acid-containing hyperbranched polytriphenylmethanol (HPTPM-BA) exhibits intriguing aggregation-induced emission-type clusteroluminescence. Attributed to the borinic acid moiety, further stimuli-responsive luminescent behavior of HPTPM-BA is carried out for the luminescent detection of 8-hydroxyquinoline (HQ) and fluoride ions. Due to the strong dative N->B bond, the HPTPM-BA-HQ complex is prepared by complexation of HPTPM-BA with HQ, which exhibits interesting dual-state emission (luminescent both in solution and in the solid state) and distinct solvent-polarity-dependent luminescence, as well as polarity-sensitive luminescence in different polymer matrices. These results therefore confirm that the borinic acid moiety is versatile in stimuli-responsive luminescent polymers and opens a new avenue for the molecular design of a stimuli-responsive clusteroluminescent polymer in one pot.