In this work,triphenylamine pyridine acetonitrile compounds Py A1,Py A2 and Py A3 are designed and synthesized.They show green fluorescence in water and bright emission in solid state.They have large Strokes shift(about 100 nm).The excitation and emission spectra are investigated in ethyl acetate,chloroform,cyclohexane,ethanol,water,acetonitrile,THF,DMF and DMSO.It is interesting to find that these compounds are able to sense increasing p H values ranging from p H 2 to 7 by showing different color and emission intensities:almost no emission at p H 2 and strong green emission at p H 7.The acid–base switched color and fluorescence changes can be observed under UV irradiation,in water solution and 1% agarose gel.These changes can be repeated for several cycles.We are able to employ these compounds for cell p H environment imaging. In this work, triphenylamine pyridine compounds Py A1, Py A2 and Py A3 are designed and synthesized. The show green fluorescence in water and bright emission in solid state. They have large strokes shift (about 100 nm). The excitation and emission spectra are investigated in ethyl acetate, chloroform, cyclohexane, ethanol, water, acetonitrile, THF, DMF and DMSO. It is interesting to find that these compounds are able to sense increasing p H values ​​ranging from p H 2 to 7 by showing different color and emission intensities: almost no emission at p H 2 and strong green emission at p H 7. The acid-base switched color and fluorescence changes can be observed under UV irradiation, in water solution and 1% agarose gel. These changes can be repeated for several cycles.We are able to employ these compounds for cell p H environment imaging.