Synthesis of a novel poly(para-phenylene ethynylene) for highly selective and sensitive sensing mercury (II) ions

A new poly(p-phenylene ethynylene) derivative with pendant 2,2'-bipyridyl groups and glycol units (PPE-bipy) has been prepared, and its metal ion sensing properties were investigated. The polymer of PPE-bipy exhibited high selectivity for Hg²⁺ as compared with Li⁺, Na⁺, K ⁺, Ba²⁺, Ca²⁺, Mg²⁺, Al ³⁺, Mn²⁺, Ag⁺, Zn²⁺, Pb ²⁺, Ni²⁺, Cd²⁺, Cu²⁺, Co, ²⁺ and Fe³⁺ in THF/EtOH (1:1, v/v) solution. The fluorescence of PPE-bipy was efficiently quenched by Hg²⁺ ions, and the detection limit was found to be 8.0 nM in a THF/EtOH (1:1, v/v) solvent system. PPE-bipy also showed a selective chromogenic behavior toward Hg ²⁺ ions by changing the color of the solution from slight yellow to colorless, which can be detected with the naked eye.