Triazole-linked amidopyrene-tagged fluorometric probe for Au3+ ions and pH control aggregation-induced emission.

In this paper, an amidopyrene-tagged reversible fluorescence probe 1 has been constructed for the detection of Au(III) ions in H2O/CH3CN (4/1, v/v). It is used to identify the Au(III) ions over several metal ions with excellent sensitivity (LOD: 0.061 µM). The fluorescence quenching of 1 with Au(III) ions might be attributed to the reverse PET process. Probe 1 recognized Au(III) by forming tetravalent geometry with the amide -NH, triazole moiety, free water, and Cl- ion in 1:1 binding mode, which is evidenced by the DFT calculations, FT-IR spectroscopy, and HRMS value of the complex. The application utility of probe 1 was ascertained from the recovery of Au(III) ions from different sources of natural water samples. Interestingly, molecule 1 also showed aggregation-induced emission behavior at basic pH (>10) in H2O/CH3CN medium with high water content. The AIE might be attributed to the formation of self-associates of 1 upon the intermolecular H-bonding interactions between water and donor atom(s) of 1 or the increased polarity of the solvent medium.

Sugar-based carboxamidoquinoline conjugate for sensing Cu2+ and Au3+ ions in water through different binding modes and real application.

A simple water-soluble carboxamidoquinoline derivative of glucofuranose 1 exhibited reversible selectivity toward Cu2+ and Au3+ ions in different binding modes. Sensor 1 is an example of a dual sensor for identifying copper and gold ions in the water medium. Sensor 1 exhibited excellent selection ability and sensitivity for Cu2+ and Au3+ ions rather than several metal ions and anions with a wide pH range (5-10). The association constants for both ions were determined to be 3.58 × 104 M-1 and 1.84 × 104 M-1, respectively. The 1:1 binding chemistry of the complexes was verified from the Job method and again validated through mass spectra. Sensor 1 can detect Cu2+ and Au3+ ions at very low concentrations, such as 0.014 µM for Cu2+ and 0.058 µM for Au3+. The different sensing strategies of sensor 1 towards Cu2+ and Au3+ were manifested from the photophysical properties of sensor 2 with metal ions, FT-IR spectra, and theoretical (DFT) observations. The useful relevance of the sensor for Cu2+ and Au3+ ions was tested in different water samples.