Synthesis and chemosensory properties of two-arm truxene-functionalized conjugated polyfluorene containing terpyridine moiety

Abstract

We report the responsive fluorescence chemosensory phenomena of a truxene-functionalized conjugated polymer (P1) with pendant terminal terpyridine (tpy) groups as receptors for metal ions synthesized via a Suzuki polymerization reaction. We examined the structural effects of the tpy units on the sensory characteristics of the fluorescent chemosensors. The weight-average molecular weight (M_w) of P1 was 1.08 × 10⁴ g mol⁻¹, with its corresponding polydispersity index being 2.25. P1 exhibited high thermal stability at a thermal decomposition temperature of 334.6 °C with a 5% weight loss. Photoluminescence titrations demonstrated that P1 exhibited a high sensing ability to Fe³⁺ ions with a Stern–Volmer constant of 1.14 × 10⁶ M⁻¹. The limit of detection for Fe³⁺ was estimated to be 2.13 × 10⁻⁷ M. The first stepwise association constant (K_a1) for the P1/Fe³⁺ complex was 4.48 × 10⁵ M⁻¹. The fluorescence of the P1 solution that was quenched by Fe³⁺ ions was recovered upon the addition of trace CN⁻ anions because of the considerably high stability constant of the CN⁻–Fe³⁺ complex. Our results suggest that the synthesized polymer is a promising material for chemosensory applications.