Optical membrane for o-nitroaniline based on fluorescence energy transfer between a small molecule and a conjugated polymer Original Research Article

A new o-nitroaniline-sensitive optical membrane has been proposed based on the fluorescence energy transfer between a small molecule 1,2-di(1-naphthyl) acetylene (DNAL, donor) and a conjugated polymer poly(p-phenylene ethynylene) (PPP, acceptor). There is large spectral overlap between the donor emission and the acceptor absorption. When DNAL and PPP were immobilized in plasticized poly(vinyl chloride) (PVC), energy transfer occurred from small molecule DNAL to conjugated polymer PPP. The fluorescence of the optical membrane based on DNAL was strongly quenched by o-nitroaniline, but that of PPP only weakly. When the optical membrane containing the DNAL/PPP contacted a solution of o-nitroaniline, the efficiency of fluorescence quenching of PPP was increased greatly. Under the optimum condition, the measuring range of o-nitroaniline was from 4.0×10−4 to 4.0×10−7 mol l−1. The present membrane exhibited good reproducibility, reversibility and selectivity in the presence of some common ions and organic compounds. The proposed optical membrane was applied to the direct analysis of spiked o-nitroaniline in Xiang River water and the results obtained were satisfactory.