A "Turn-on" Schiff base Fluorescent Probe for Recognizing Al3+ and its Application.

A fluorescent probe, DZM, was synthesized via a dehydration condensation reaction using 2-hydroxy-1-naphthaldehyde and 9-fluorenylmethyl carbazate as starting materials. The DZM solution exhibited a significant fluorescence enhancement (297-fold) upon the addition of Al3⁺, along with high selectivity for this ion. The calculated detection limit was as low as 0.81 nM, which was much lower than most of the values reported, demonstrating high sensitivity. The binding stoichiometry between DZM and Al3⁺ was confirmed to be 2:1 by Job's plot and 1H NMR, and the sensing mechanism was elucidated, which was further supported by Gaussian calculations confirming the presence of a photoinduced electron transfer (PET) process. Furthermore, the probe DZM was successfully employed in biological experiments and cellular fluorescence imaging.