Luminescent polyethylene with side-chain triarylboranes: Synthesis and fluoride sensing properties

The direct copolymerization of ethylene with an electron-deficient borane monomer (1) using a single-site catalytic system, Me2Si(η5-C5Me4)(η1-N-tBu)TiCl2 (CGC)/methylaluminoxane (MAO) efficiently leads to the novel class of luminescent polyethylene with pendent triarylborane groups. The catalytic system provides high-molecular-weight copolymers with controlled incorporation of 1. Characterization by multinuclear NMR spectroscopy reveals that the copolymers constitute a well-defined polymer structure with base-free tricoordinate boron centers. While UV–vis absorption and PL spectra of copolymers display almost identical absorption and emission features with those of 1, the copolymer (8.8 mol% of 1) shows the enhanced emission quenching efficiency with 70% amplification effect upon addition of fluoride ion in solution. Particularly, the thin film of the copolymer exhibits the high fluorescence quenching response in the presence of a very low concentration of fluoride ion (4.5 μM) in THF.