Photoluminescent Ester Oligomers Containing Curcumin Dye Units: A Selective Fluorescent “Turn off” Chemosensor for Ferric Ions

New curcumin-based ester oligomers were synthesized via polycondensation of curcumin diol with aromatic diacid. The oligomers were characterized by elemental analysis, 1H-NMR, 13C-NMR, FT-IR and TGA. The onset of thermal degradation was at 280°C and ester oligomers with longer alkyl chains showed lower thermal stability. Photoluminescence properties of the ester oligomers were examined by using UV-Vis and fluorescence spectroscopies. The ester oligomers exhibited green emission under UV irradiation. Selective fluorescence quenching was observed upon the addition of ferric (Fe3+) ions over other heavy metal cations. The result suggested the new curcumin-based ester oligomers can be potential chemosensors for Fe3+ ions.