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

Abstract

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.