Enhancement and quenching of fluorescence of Quin-2 by metal ions

Abstract

Addition of aqueous solutions of metal ions (La 3+, Dy 3+, Nd 3+, Eu 3+, Lu 3+, Sc 3+, Al 3+, and Be 2+) to the fluorescence probe Quin-2 induced changes in the 490 nm emission band (excitation at 334 nm). The resulting spectra were qualitatively different and provided a “signature” for the individual metal ions. The lanthanide metal ions showed decreasing fluorescence emission at 490 nm. Lu 3+ and Sc 3+ caused a decrease in the emission intensity at 490 nm and a substantial increase in emission intensity at 400 nm or 412 nm, respectively. In all instances, stoichiometry indicated an apparent 1:1 binding ratio, except for Al 3+ and Be 2+, which showed no significant effect on the fluorescence.