Spectroscopic and theoretical studies on a novel bis(salamo)-like probe for highly effective fluorimetric-colorimetric identification of Fe3+ and Cu2+ in aquo-organic medium.

A novel bis(salamo)-type sensor FT for fluorescence-colorimetric recognition of Fe³⁺/Cu²⁺ has been created, which revealed significant fluorescent performance and colorimetric sensing ability for Cu²⁺ and Fe³⁺ ions, superior to other related competitive metal ions. Interestingly, the binding of the FT probe with Cu²⁺ ions manifested an instant color change from colorless to red in sunlight, which is detectable by the naked-eye, and a fluorescence turn-off response under UV light for Fe³⁺ and Cu²⁺. The results demonstrated that the probe exhibits better sensitivity, greater affinity and lower limit of detection leading to quick response time in an aquo-organic medium. The excited state property of the FT probe and in the presence of Cu²⁺/Fe³⁺ was evaluated on the basis of DFT & TD-DFT results. Furthermore, test strips have been provided for convenient monitoring of Cu²⁺ and Fe³⁺ ions by naked eye and fluorescence method.