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 Al 3+ cation, based on metal chelation-enhanced fluorescence (CHEF) effects that inhibit the nonradiative PET and ESIPT processes. In aqueous solution, Al 3+ selectively induces strong fluorescence of these compounds with large Stokes shifts up to ∼133 nm and emission colors varying from blue to orange. In the solid phase, both Al 3+ and Zn 2+ give apparent fluorescence which is simultaneously detected based on chromatographic separation.