Tuning the selectivity of two fluorescent probes to Cr(III) and Pb(II)

Two rhodamine-based fluorescent probes were synthesized, and their sensing behavior toward metal ions was investigated by fluorescence spectroscopy. Small structural modifications (tuning) of the compounds afforded enhanced fluorescence in the presence of Cr(III) and Pb(II) in CH3CN solution, whereas other ions including Zn(II), Ni(II), Hg(II), Cd(II), Co(II), Fe(III), Mn(II), Fe(II), Na(I), and Ag(I) induced basically no or small spectral change. The compounds therefore constitute a Cr(III)-selective and a Pb(II)-selective fluorescent probe, respectively.