A novel pH probe based on ratiometric fluorescent properties of dicyanomethylene-4H-chromene platform

Publication date: 1 November 2017
Source:Talanta, Volume 174
Author(s): Xiaolei Liu, Jixun Han, Yan Zhang, Xiaofeng Yang, Yu Cui, Guoxin Sun
We report here a ratiometric pH probe (Z)−2-(2-(2-(4-hydroxyphenyl)−2-(pyrrolidin-1-yl)vinyl) −4H-chromen-4-ylidene)-malononitrile over the pH range of 2.44–6.00. It was synthesized by Knoevenagel Reaction from dicyanomethylene-4H-chromene and pyrrolidine. This is the first example of pyrrolidine as a part of the product structure in Knoevenagel condensation. High selectivity and sensitivity for pH variation were observed with significant fluorescent ratiometric responses and a remarkable Stokes shift (about 138nm). The probe was stable in the studied solvent and no obvious fluorescence changes were detected in acidic media within one month at room temperature.

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