Spectral response of a methylimidazolium-functionalized polythiophene to phosphates

We report on the colorimetric and fluorimetric responses of the cationic water-soluble polythiophene derivative poly[3-(2-(N-(N′-methylimidazole))ethoxy)-4-methylthiophene] in presence of different phosphates with a focus on ATP. UV/Vis absorbance and fluorescence measurements show that ATP concentrations can be determined in aqueous solutions with a sufficient selectivity to other phosphates. Measurements of circular dichroism reveal that the polymer forms a random coil structure that exhibits no signal in the CD spectrum. Upon addition of ATP the conformation changes to a helix, yielding in strong CD peaks. These experimental data suggest that this polymer is an attractive, simple and versatile colorimetric and fluorimetric probe for nucleoside triphosphates such as ATP.

► Methylimidazolium-derived polythiophene as molecular probe for ATP recognition.
► Specific colorimetric, fluorimetric and CD response.
►  Fluorescence quenching by aggregation of polymers in presence of triphosphates.
► Additional quenching effect by guanosine.