Searching for New Luminescent Sensors: Synthesis and Photophysical Properties of a Tripodal Ligand Incorporating the Dansyl Chromophore and of Its Metal Complexes

The new tripodal ligand 1 containing the dansyl chromophore has been synthesized and characterized. The intense luminescence characteristic of the chromophore is maintained in the ligand structure, showing that no intramolecular interactions are present. This ligand has been shown to complex in acetonitrile/water solutions only with Cu2+, Co2+, Zn2+, and Cd2+ ions, with concomitant pronounced changes in the fluorescence spectra. The complexation is controlled by pH conditions: at neutral pH this ligand shows a remarkable selectivity towards Cu2+ ions, suggesting a possible use for 1 as a luminescent chemosensor for this ion.