Synthesis of terpyridine-functionalized poly(phenylenevinylene)s: The role of meta-phenylene linkage on the Cu2+ and Zn2+ chemosensors

A meta-phenylene-containing poly(phenylenevinylene) (PPV) with pendant terdentate terpyridine ligand 2b was synthesized and its fluorescence properties were compared with its isomeric PPV. The meta-phenylene bridge interrupts the resonance connection between the PPV backbone and the metal-chelation sites, while jointing the structurally defined chromophores together. The fluorescence of the polymer, with emission λem = 460 nm and ϕfl ≈ 0.45, is found to be selectively quenched by Cu2+ ion with interference from Co2+ and Ni2+ ions. The nature of the quenching process in 2b is probed by using Stern-Volmer analysis, revealing that the quenching results from both dynamic collision and metal chelation. Addition of Zn2+ and Cd2+ ions only induces partial fluorescence quenching, accompanied with a broad new emission band occurring at ∼560 nm. With the aid of a model compound study, the new emission band at 560 nm is attributed to the complex formation with terpyridine to Zn ratio of 1:1. The study finds that the polymer has the potential for Cu2+ and Zn2+ sensors.