Synthesis and photophysical properties of dansyl-based polyamine ligands and their Zn(II) complexes

The synthesis, potentiometric studies and photophysical properties of two new polyamine ligands (L1 and L2) possessing the dansyl chromophore were studied in aqueous 0.15 M NaCl. The compounds show the absorption and emissions bands characteristic of the dansylamide fluorophore and both present intramolecular excited state proton transfer at intermediate pH ranges. One of the ligands (L2) strongly coordinates Zn(II) leading to fluorescence quenching. A model compound (L3) of the dansyl moiety was also investigated.

Dansyl labelled polyamine ligands L1 and L2 were synthesised and their photophysical properties studied as well as those of the ZnL22+. Both ligands present intramolecular excited state proton transfer at intermediate pH ranges that lowers the emission of the dansyl fluorophores. The coordination of Zn(II) to the pyridine units of L2 contributes to a further decrease in fluorescence.Figure optionsDownload as PowerPoint slide