A novel solvent-dependently bifunctional NIR absorptive and fluorescent ratiometric probe for detecting Fe3+/Cu2+ and its application in bioimaging

A novel rhodamine-cyanine based probe LS1 was designed and synthesized, which can act as a bifunctional NIR ratiometric colorimetric and fluorescent probe for detecting Fe3+ and Cu2+ in solvent of MeOH/H2O and MeCN/H2O respectively. As expected, it exhibited high selectivity and sensitivity for detecting Fe3+ and Cu2+ over other commonly coexistent metal ions in their respective systems with a broad pH span. The detection limit was measured to be 0.737 μM for Fe3+ and 1.019 μM for Cu2+. Furthermore, fluorescence imaging experiments of Cu2+ ions in living SH-SY5Y109 cells demonstrated its value of practical application in biological systems.