An rhodamine-based fluorescence probe for iron(III) ion determination in aqueous solution

An “off-on” rhodamine-based fluorescence probe for the selective signaling of Fe(III) has been designed exploiting the guest-induced structure transform mechanism. This system shows a sharp Fe(III)-selective fluorescence enhancement response in 100% aqueous system under physiological pH value and possesses high selectivity against the background of environmentally and biologically relevant metal ions including Al(III), Cd(II), Fe(II), Co(II), Cu(II), Ni(II), Zn(II), Mg(II), Ba(II), Pb(II), Na(I), and K(I). Under optimum conditions, the fluorescence intensity enhancement of this system is linearly proportional to Fe(III) concentration from 6.0 × 10⁻⁸ to 7.2 × 10⁻⁶ mol L⁻¹ with a detection limit of 1.4 × 10⁻⁸ mol L⁻¹.