An Off-On Near-Infrared Fluorescent Probe for Cu2+ Detection in Living Cells

A near-infrared fluorescent probe (6) was designed and synthesized by using 2-(6-(dimethylamino)naphthalen2-yl)-7-hydroxy-4H-chromen-4-one as report group and 2-picolinate as recognition group. The probe was identified by H-1 NMR, C-13 NMR, MS and elemental analysis. The probe could react specifically with Cu2+ and its fluorescence intensity increased obviously at 655 urn, at the meantime, the color change of the solution can be seen by naked eves. A linear relationship was obtained between the fluorescence intensity and concentration of Cu2+ in the range of 0 similar to 2.0X 10(-5) mol/L, and the detection limit was 3.2 X 10(-8) mol/L. The mechanism study showed that Cu2+ catalyzed the cleavage of the ester bond and strongly fluorescent 2-[6-(NA-dimethylamino)naphthyl]-7-hydroxy-4H-chromen-4-one (5) was generated. In addition, the probe 6 could be used for fluorescence imaging of Cu2+ in living cells.