Photoluminescence and ion sensing properties of a bipyridyl chromophore-modified semifluorinated polymer and its metallopolymer derivatives

A difluorovinylene aromatic ether polymer (P1) incorporating periodic 5,5′-distyryl-2,2′-bipyridyl units as metal chelating chromophores was prepared by a transition metal-free step-growth polymerization. P1 displays strong ionochromic and ionoluminescent effects in response to transition metals. Although significant emission quenching is observed upon exposure to most transition metal ions, bathochromically shifted emission is observed upon addition of divalent d10 ions (Zn2+, Cd2+ and Hg2+). A selective 10-fold increase in integrated emission intensity is observed upon addition of Zn2+ to P1. The Zn2+-P1 metallopolymer acts as a ratiometric fluorescent indicator selective for fluoride anions, and the Cu2+-P1 metallopolymer exhibits a striking turn-on fluorescence response (>100-fold increase in integrated intensity) selective for cyanide and fluoride anions.