Ratiometric and selective fluorescent chemodosimeter for Cu(II) by Cu(II)-induced oxidation.

A new rhodamine derivative, rhodamine B 4-N,N-dimethylaminobenzaldehyde hydrazone (1), was designed for ratiometric sensing of Cu(II) selectively. A red-shift from 515 to 585 nm was observed in the fluorescence spectrum when Cu(II) was added to 1 in acetonitrile. Other metal ions of interest showed no ratiometric response. The interaction between Cu(II) and 1 was found to be the Cu(II)-induced oxidation of 1.