Synthesis of new colori/fluorimetric chemosensor for selective sensing of biologically important Fe³⁺, Cu²⁺ and Zn²⁺ metal ions.

New Schiff base chemosensors (1 and 2) based on aryl ether amine were synthesized and demonstrated positional isomer and functional group dependent colori/fluorimetric sensing of Fe(3+), Cu(2+) and Zn(2+) at ppm level. Methoxy salicylaldehyde based chemosensor 1 exhibited selective colorimetric sensing of Fe(3+) whereas 2-hydroxy naphthaldehyde based chemosensor 2 showed selective disappearance of yellow color for Cu(2+) ions. Interestingly, both 1 and 2 exhibited a highly selective strong turn-on fluorescence for Zn(2+). The significance of COOH group in 1 and 2 for Zn(2+) turn-on fluorescence sensing has been confirmed by structure-property studies. Concentration dependent studies of 1 and 2 indicate that Fe(3+), Cu(2+) and Zn(2+) can be detected up to 10 μM. The formation of 1:1 Zn(2+) and chemosensor (1 and 2) confirmed by NMR studies. High selectivity of 1 and 2 was demonstrated by interference studies in presence of different metal ions.