New “on–off” optical probe based on Schiff base responding to Al3+ ions: Logic gate application

• Two new luminescent “turn-on” probes were developed for the distinct detection of Al3+.
• The receptors showed high sensitivity and selectivity for Al3+ over other metal ions.
• The logic gate function of the receptors was exhibited through the emission mode.

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.

Luminescent probe based on imine-hydroxy moieties as a binding unit for the differential response of Al3+ was demonstrated. Interestingly, sensing mechanism exposed the fluorescence ‘turn-on’ behaviour of the receptor with growing addition of Al3+ excited under the UV lamp at 375 nm in methanol.Figure optionsDownload as PowerPoint slide