Novel fluorene-based copolymer with pendant aza-crown ether: Highly sensitive and specific detection for CuSO4 and concurrent effect of anions

A novel fluorene-based copolymer with aza-15-crown-5 as pendant group was synthesized by Suzuki-coupling reaction, and characterized by 1H NMR, 13C NMR, EA, and GPC. The polymer was brightly blue emissive in common organic solvents, such as CHCl3, CH2Cl2, and THF. Fluorescent titration experiments carried out in THF–MeOH system indicate that the polymer has quite good selectivity and high sensitivity for CuSO4, which is contrasting to the weak responses for other copper salts such as Cu(ClO4)2, CuCl2, Cu(NO3)2, and Cu(OAc)2. Molecular simulation result suggests that this unique phenomenon may come from the synergistic effect of the bivalent counterion SO42−. This new system utilizing the strong luminescent property of polyfluorene as reporter and concurrent effect of the counterion SO42− may be developed as chemosensor for the special detection for CuSO4.