We synthesized two new probers which have similar structures, however their optical properties are very great differences.
The structure of the sensor boldFont">L1 is original for the detection of pH and Fe3+ simultaneously.
A new structure formed from compound boldFont">L2 upon acidification and result in the generation of the isosbestic point.
We have proved the structure change of boldFont">L2 upon acidification by absorption spectra, 1H NMR and DFT/TDDFT calculation.