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The host-guest complex of water-soluble phosphate salt pillar[5]arene (PP5A) and cationic fluorescent dye acridine orange (AO) was constructed, and studied with ultraviolet spectrum (UV), infrared absorption spectrum (IR), molecular fluorescence spectroscopy (MFS), and nuclear magnetic resonance (NMR) spectra (1H NMR and NOESY). And then, the effect of pH and two surfactants, including sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB) on the fluorescence intensity of AO/PP5A complex system were investigated. Finally, the complexation mode and energy of PP5A with AO and CTAB were calculated by molecular docking. The results showed that AO and PP5A formed a 1:1 host-guest complex. PP5A reduced or quenched the fluorescence intensity of AO in the pH range of 3~11. The addition of SDS and CTAB did not affect the fluorescence intensity of AO/PP5A complex significantly. The fluorescence changes generated by AO and PP5A complexation can provide a theoretical basis for the design of fluorescence sensors.

A novel fluorescent probe, amino-pillar[5]arene (APA), was prepared via a green, effective, and convenient synthetic method, which was characterized by nuclear magnetic resonance (NMR), infrared (IR), and high-resolution mass spectrometry. The fluorescence sensing behavior of the APA probe toward 22 metal ions in aqueous solutions were studied by fluorescence spectroscopy. The results showed that APA could be used as a selective fluorescent probe for the specificity detection of Au 3+ ions. Moreover, the detection characteristics were investigated by fluorescence spectral titration, pH effect, fluorescence competitive experiments, Job's plot analysis, 1 H NMR, and IR. The results indicated that detection of Au 3+ ions by the APA probe could be achieved in the range of pH 1-13.5 and that other coexisting metal ions did not cause any marked interference. The titration analysis results indicated that the fluorescence intensity decreased as the concentration of Au 3+ ions increased, with an excellent correlation ( R 2 = 0.9942). The detection limit was as low as 7.59 × 10 -8 mol·L -1 , and the binding ratio of the APA probe with Au 3+ ions was 2:1. Therefore, the APA probe has potential applications for detecting Au 3+ ions in the environment and in living organisms., Competing Interests: The authors declare no competing financial interest., (Copyright © 2019 American Chemical Society.)