Novel Turn-On Fluorescent Sensors with Mega Stokes Shifts for Dual Detection of Al3+ and Zn2+

A series of bishydrazide compounds have been developed for selective turn-on detection of Al3+ cation, based on metal chelation-enhanced fluorescence (CHEF) effects that inhibit the nonradiative PET and ESIPT processes. In aqueous solution, Al3+ selectively induces strong fluorescence of these compounds with large Stokes shifts up to similar to 133 nm and emission colors varying from blue to orange. In the solid phase, both Al3+ and Zn2+ give apparent fluorescence which is simultaneously detected based on chromatographic separation.