Chromogenic, specific cascade detection of fluoride and alkaline earth metal ions

Abstract

A salen-based colorimetric chemosensor (MM) has been designed and synthesized to selectively recognize F− and alkaline earth metal ions in solution and solid phase, respectively. A ratiometric UV–visible absorption spectral change with a colorimetric visualization from yellow to pink is observed in the presence of F− ions. The detection of F− ions is fully reversible in alkaline earth metal ions. The limit of detection (LOD) of F− ions by our as-prepared MM could be possible down to the μM range. A paper strips-based test kit has been fabricated to detect F− ions selectively by the naked eye. A smartphone-based assay analysis is also successfully performed to identify F− ions in the non-aqueous media. Such a dual ions sensing system with excellent reversibility and repeatability prompted us to consider probe MM a viable choice for fabricating molecular logic circuits and set-reset memorized molecular devices.