A Reversible and Highly Selective Fluorescent Sensor for Mercury(<scp>II</scp>) Using Poly(thiophene)s that Contain Thymine Moieties

Abstract Summary: A reversible and highly selective assay method has been developed to detect mercury( II ) (Hg 2+ ) ions using a conjugated polymer (CP). The transduction mechanism is based on Hg 2+ ‐mediated interpolymer π ‐stacking aggregation, which results in the fluorescence self‐quenching of the CP. CPs that contain thymine moieties, poly[3‐( N ‐thymin‐1‐ylacetyl)ethylamine‐thiophene] (PTT), have been synthesized and characterized. In the absence of Hg 2+ ions, the PTT chains remain separated from each other and the CP exhibits strong fluorescence emission. Upon adding Hg 2+ ions, the formation of interpolymer π ‐stacking aggregation induced by specific thymine–Hg–thymine interactions results in the fluorescence quenching of PTT. Distinguishing aspects of this assay include the signal amplification of CPs and the specific binding of Hg 2+ ions to thymine‐thymine (T–T) base pairs. The binding of Hg 2+ ions causes the separate conducting polymer chains to aggregate with subsequent fluorescence self‐quenching. magnified image The binding of Hg 2+ ions causes the separate conducting polymer chains to aggregate with subsequent fluorescence self‐quenching.