A dual-response fluorescent probe for Zn and Al detection in aqueous media: pH-dependent selectivity and practical application.

A Schiff base-type fluorescent probe (1) consist of 2-hydroxynaphthaldehyde and glutamide moieties has been designed and synthesized for detection Zn and Al. The probe shows pH dependent dual-selectivity for Zn and Al in Tris-HCl buffer, viz. that can selectively recognized Zn at pH 7.4 and Al at pH 6.0, respectively. From Job's plots and MS data, the stoichiometric ratios of the probe with Zn and Al appeared to be 1:1 and 2:1, respectively. The probe can detect as low as 5.5 × 10 M Zn and 1.27 × 10 M Al, whereas respective association constants are 4.27 × 10 M and 3.50 × 10 M. Furthermore, it is also confirmed that the probe has good cell-permeability and could thus be used to selectively sense intracellular Zn and Al by bioimaging in different pH environment. Finally the probe has been used successfully for determination of the analytes in real drug samples.