New "on-off" optical probe based on Schiff base responding to Al³⁺ ions: Logic gate application

Two extremely sensitive spectrophotometric receptors namely as N,N′-bis(o-hydroxyacetophenone)-m-phenylenediamine (P) and N-(o-hydroxyacetophenone)-o-phenylenediamine (Q), based on imine-hydroxy moieties as a binding and signalling unit, have been synthesized and characterized by means of various spectroscopic techniques. The receptors show an instantaneous response towards Al³⁺ ions through selective fluorescent enhancement, attributed to chelation enhanced fluorescence effects. The spectrophotometric behavior of the receptors in the presence of Al³⁺ ions was significantly compared with those of other metal cations tested. The synthesized receptors worked effectively in the physiological pH range. Further, the integrated logic gate nature based on Al³⁺ and EDTA titration, through the emission mode has also been described. Thus, these receptors offer a novel turn-on fluorescent approach for the selective detection of Al³⁺ ions qualitative as well as quantitative in biological and environmental samples.