Non‐Ionic Water‐Soluble Crown‐Ether‐Substituted Polyfluorene as Fluorescent Probe for Lead Ion Assays

A new non‐ionic water‐soluble polyfluorene that contains two benzo‐18‐crown‐6 side chains per repeat unit (PFDC) is synthesized and characterized. Upon addition of Pb2+ ions to a solution of PFDC, the PFDC fluorescence is strongly quenched. The minor interference from other metal ions, especial from Cu2+ and Hg2+ions, clearly shows that the PFDC can be used to detect Pb2+ ions with high selectivity. The fluorescence quenching of PFDC in solution originates from the multivalent coordination of the crown‐ether moieties to Pb2+ ions followed by precipitation. In comparison to ionic conjugated polymers, the pH of the medium shows less effect on the binding of non‐ionic PFDC to Pb2+ ions. magnified image