Synthesis of terpyridine-functionalized poly(phenylenevinylene)s: The role of meta-phenylene linkage on the Cu and Zn 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 λ_em = 460 nm and ?_fl ≈ 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.