A novel europium(III) complex with versatility in excitation ranging from infrared to ultraviolet

One- and two-photon absorption properties of a novel europium(III) complex containing a hemicyanine cation are investigated in this paper; in which the sensitization wavelength of europium(III), induced by beta-diketonate ligands, is in the ultraviolet range, and the hemicyanine(aminostyrylpyridinium) cation extends the sensitization wavelength of Eu(III) to visible region. Furthermore, under 1.06 μm ultrashort pulse laser excitation, the complex exhibits effective europium(III) luminescence induced by the two-photon absorption of the hemicyanine cation. Therefore, this new europium(III) complex with excitation bands in the near infrared, visible and ultraviolet ranges. Since the 1.06-μm ultrafast laser is one of the most frequently used laser sources and 1.06 μm is an ‘optical window’ for cells and tissues, the results suggest that this kind of complex has promising applications in deep-penetrating and high quality bioimaging in vivo.