Cu and CN-selective fluorogenic sensors based on pyrene-appended thiacalix[4]arenes

Two new fluorescent sensors 1 and 2 based on thiacalix4]arenes bearing pyrene moieties have been synthesized in cone conformation. The binding abilities of these sensors towards different cations such as lithium, sodium, potassium, nickel, cadmium, copper, zinc, lead, silver, mercury and anions like fluoride, chloride, bromide, iodide, cyanide, acetate, hydrogen sulfate and nitrate have been examined by UV-vis and fluorescence spectroscopies. These receptors show pronounced selectivity for copper and cyanide ions. In CH₂Cl₂/CH₃CN (1:1), the presence of Cu(II) ion induces the formation of 1:1 (H/G) complex with receptor 1 and 1:2 (H/G) complex with receptor 2. The cyanide ions form a 1:1 (H/G) complex with both receptors.