A dual site controlled probe for fluorescent monitoring of intracellular pH and colorimetric monitoring of Cu2+

A novel dual site controlled probe has been developed on the basis of rhodamine and biphenylcarbonitrile unit. The probe showed not only rapid fluorescence response to pH, but also good colorimetric recognition performance for copper ions in the HEPES buffer solution (pH 7.0). The optimal geometric configuration of the probe RhB-H with different structures and the [RhB-H-Cu 2+ ] complex were calculated at B3LYP level by DFT method. On this basis, the response mechanism of pH was analysed combining with the 1 H NMR titration experiment. Moreover, the cytotoxicity studies indicated that the probe had good biocompatibility and low toxicity. Then the probe was also successfully applied on real-time monitoring of the intracellular pH changes by exhibiting different fluorescence and emission intensity. These results demonstrated that the probe could be usefully involved in biological and biomedical research.