A New Azo-Schiff Base Dual-mode Chemosensor: Colorimetric Detection of Cobalt Ions and Fluorometric Detection of Aluminum Ions in Aqueous Ethanol Solution

A new Azo-Schiff base ligand (H2L) was designed and synthesized as a cation chemosensor. The chemosensor H2L as dual chemosensor showed selective fluorescence recognition of Al3+ with a noticeable fluorescence enhancement and colorimetric detection of Co2 + in aqueous ethanol solution. The H2L exhibits a linear response toward Al3+ ions in the concentration range of 1.91 × 10–8 M to 4.8 × 10–6 M with a limit of detection of 1.91 × 10–8 M. The sensing mechanism of sensor H2L toward Al3+ was investigated by 1H NMR and IR spectroscopies. Fluorescence switch based on the control of EDTA and Al3+ proved H2L could act as a reversible chemosensor. The molecular structure of [NiL] complex has been determined by X-ray crystallography.