Selective two way Cd(II) and Co(II) ions detection by 1,2,3–triazole linked fluorescein derivative

[Display omitted] •The paper insights about the sensing of Cd(II) and Co(II) ions by a fluorescein derivative.•The senor efficiently recognizes Cd(II) and Co(II) ions competitively in a mixture of cations.•The Cd(II) ion detection is a solvent induced phenomenon and displays self-quenching in chloroform. This report presents unique “on-off” system for the detection of Cd(II) and Co(II) metal ion using 1,2,3-triazole linked fluorescein chemosensor (FLT). The studies were performed in 4:1 ethanol/water (v/v) solution and present an excellent “turn-off” and “turn-on” response with the Cd(II) and Co(II) metal ions, respectively. The need to develop FLT sensor was propelled by the high toxicity of Cd(II) and Co(II) ions in water and their competitive detection, with the naked eye, in aqueous solution of metal ion mixture. The high selectivity and specificity of 1,2,3-triazole containing FLT probe, consisting of fluorescein backbone, owes to Photo Electron transfer (PET) mechanism.