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 Cd(2+) in aqueous solution. PBQ was found to have excellent selectivity for Cd(2+) over many other metal ions (Ba(2+), Mn(2+), Hg(2+), Ni(2+), Ca(2+), Cu(2+), Co(2+), Pb(2+), Mg(2+), Zn(2+), Fe(2+), Fe(3+), Cr(3+), Ag(+), Li(+), Na(+), K(+)). Significantly, its fluorescence intensity was enhanced in a linear fashion with the concentration of Cd(2+). Thus PBQ can be potentially used for the quantification of Cd(2+). Moreover, a series of model compounds were rationally designed and synthesized in order to explore the binding mode of PBQ with Cd(2+).