Dual-response fluorescence sensor for detecting Cu2+ and Pd2+ based on bis-tetraphenylimidazole Schiff-base

Abstract

Although the fluorescence sensors for Cu2+ or Pd2+ had been prepared, the sensor of in-situ detecting both Cu2+ ion and Pd2+ ion in aqueous media was rarely concerned. Herein, a bis-tetraphenylimidazole Schiff-base (Bis-TPI) with aggregation-induced emission was designed and prepared in yield of 88%. Bis-TPI displayed strong red fluorescence at 550–650 nm in aqueous media and selectively response on detecting Cu2+ and Pd2+ with quenched fluorescence. The detection limits attained 8.3 × 10-7 M for Cu2+ and 9.2 × 10-7 M for Pd2+, respectively. The mutual interference on detecting Cu2+ and Pd2+ in their coexistence system was eliminated by the masking reagent of adenosine triphosphate for Cu2+, realizing the detection of Cu2+ and Pd2+ sequentially. The sensing mechanism of 1:1 binding system was supported by FT-IR spectra, binding MS spectra, 1H NMR spectra and fluorescence Job’s plot. Moreover, Bis-TPI showed good fluorescence bioimaging property and achieved in-situ detection on Cu2+ and Pd2+ in living-cell system, implying the application prospect on in-situ sensing Cu2+ and Pd2+ in both vitro environment and vivo assay.