Synthesis, characterization and photophysical properties of novel fluorene-based copolymer with pendent urea group: Fluorescent response for anions through H-bonding interaction

A novel fluorene-based copolymer P₁ with diphenyl urea as pendent group, as well as its analogous copolymer P₂ without urea group for comparison, were synthesized by Suzuki-coupling reaction, and characterized by ¹H NMR, EA, IR and GPC. The polymers were brightly blue emissive in THF, DMF, or DMSO solution. Anion titration experiments carried out in THF indicate that the polymer P₁ has good selectivity for fluoride ion, acetate ion, and dihydrogen phosphate ion, and the sensitivity and selectivity of P₁ toward these anions come from the strong hydrogen-bond interaction between the anions and the urea group of the copolymer. This new system utilizing the strong luminescence property of the polyfluorene as reporter and the hydrogen-bond-forming ability of urea group may act as novel effective anions receptor and chemosensor.