Sugar-based carboxamidoquinoline conjugate for sensing Cu and Au ions in water through different binding modes and real application.

A simple water-soluble carboxamidoquinoline derivative of glucofuranose 1 exhibited reversible selectivity toward Cu and Au 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 Cu and Au 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 × 10 M and 1.84 × 10 M, 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 Cu and Au ions at very low concentrations, such as 0.014 μM for Cu and 0.058 μM for Au. The different sensing strategies of sensor 1 towards Cu and Au 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 Cu and Au ions was tested in different water samples.