Turn-on detection of Al and Zn ions by a NSN donor probe: reversibility, logic gates and DFT calculations.

An efficient dual functional naphthalene-derived Schiff base NpSb probe has been synthesised and evaluated for its fluorescence and chromogenic response towards metal ions. The NpSb probe was capable of selectively recognising Al and Zn ions when they were excited at the same wavelength in an aqueous organic solvent system. Almost non-fluorescent NpSb displayed a 'turn-on' fluorescence response when treated with Zn ( = 416 nm) and Al ( = 469 nm) ions due to the chelation-enhanced fluorescence (CHEF) effect. The limit of detection (LoD) values for Al and Zn have been determined to be 38.0 nM and 43.0 nM, respectively. The binding constants for Al and Zn were found to be 1.18 × 10 M and 3.5 × 10 M, respectively. The NpSb also acted as a colorimetric sensor for Al as the colour of the probe's solution turned to pale green from colourless upon Al addition. The binding mechanism between NpSb and Zn/Al was supported by the ESI-MS, Job's plot, NMR, and DFT studies. The reversibility experiments were carried out with an F ion and EDTA with the development of corresponding logic gates. Moreover, NpSb could be applied to detect Al ions in real samples such as tap water, distilled water and soil samples.