A N-aryl-1,8-naphthalimide based sensor (ES-1) bearing a trimethylsilyl ether has been synthesized by a two-step reaction for quantitative detection of fluoride (F(-)). ES-1 exhibited monomer/excimer emissions at 410 and 524 nm respectively in CH2Cl2. In the presence of F(-), the desilylation of trimethylsilyl ether caused decay of the excimer emission as well as enhancement of the monomer emission to give a ratiometric signal. The fluoride-triggered desilylation showed a high reaction rate and high affinity to F(-) over nine other interfering anions. ES-1 provided a novel fluorescence assay based on excimer-monomer switch of N-aryl-1,8-naphthalimide to quantitatively measure F(-) with a detection limit of 0.133 ppm.

NCy3, a derivative of Cyanine 3 with a nitro substituent, showed a high reactivity to bisulfite in aqueous media, instantly leading to ratiometric change of absorption spectra and significant fluorescence quenching. Applied in the microfluidic channel, NCy3 functionalize as a sensitive approach for quantitative detection of bisulfite, particularly for samples with a small volume.