Two AIE-active Schiff base fluorescent probes for highly selective recognition of Cu ions.

Two helical Schiff base compounds (HTPA and HTPE) containing a triphenylamine (TPA) or tetraphenylethylene (TPE) scaffold were successfully synthesized and characterized. Both HTPA and HTPE exhibited typical aggregation-induced emission characteristics in the mixed solvent of THF/HO. The two compounds also showed high selectivity and sensitivity for the recognition of Cu over other ions in THF/HEPES (1:4, V/V, pH = 7.4, 2.0 × 10 M), and could be used as turn-off fluorescent probes for Cu. The stoichiometric ratios and association constants were estimated via Job's plots and UV-vis spectra titration, and the detection limits of HTPA and HTPE toward Cu were calculated to be 2.41 × 10 M and 1.38 × 10 M, respectively. Besides, the crystal structure of the complex obtained from the interaction of HTPA with Cu well illustrated the binding modes, which helped us understand the Cu recognition mechanism of HTPA and HTPE. Moreover, the detection of Cu and spiked recovery experiments were carried out, which indicated that the two probes can be applied to Cu detection in real samples with satisfactory recoveries.