A simple fluorescent probe for Cd²⁺ in aqueous solution with high selectivity and sensitivity

A simple quinoline-based fluorescent probe, PBQ, which contained a tweezer-like receptor, was successfully developed via one-step synthesis. PBQ exhibited a 40-fold fluorescence enhancement response to Cd²⁺ in aqueous solution. PBQ was found to have excellent selectivity for Cd ²⁺ over many other metal ions (Ba²⁺, Mn²⁺, Hg²⁺, Ni²⁺, Ca²⁺, Cu²⁺, Co ²⁺, Pb²⁺, Mg²⁺, Zn²⁺, Fe ²⁺, Fe³⁺, Cr³⁺, Ag⁺, Li⁺, Na⁺, K⁺). Significantly, its fluorescence intensity was enhanced in a linear fashion with the concentration of Cd²⁺. Thus PBQ can be potentially used for the quantification of Cd²⁺. Moreover, a series of model compounds were rationally designed and synthesized in order to explore the binding mode of PBQ with Cd²⁺.