A Water-Soluble Organometallic Conjugated Polyelectrolyte for the Direct Colorimetric Detection of Silver Ion in Aqueous Media with High Selectivity and Sensitivity

A water-soluble organometallic conjugated polyelectrolyte P1 and its corresponding model complex M1 based on an aspartic acid-substituted fluorene spacer are reported, which possess good water solubility as well as intriguing fluorescent and phosphorescent dual-emissive properties in a completely organic-free aqueous medium at room temperature. A new colorimetric silver ion sensor based on P1 is developed, which shows high selectivity and sensitivity for Ag+ ions in buffered water solution because of the Ag+-induced intersystem crossing from the singlet to triplet states. The obvious color change from colorless to yellow upon exposure to Ag+ ion is visible to the naked eyes and can be quantified colorimetrically by the visible absorption spectroscopic method. On the basis of the fluorescence intensity of P1 obtained in the fluorescence titration curves, a linear relationship is observed in the Stern−Volmer plot at low concentrations (1−5 μM), and the corresponding Stern−Volmer quenching constant (KSV) of ...