Catalysis of ionic reactions by polyelectrolytes. IV. Quenching of the quinine cation fluorescence by Fe++, Ag+, and Br− in solutions of poly(vinylsulfonic acid)

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Abstract
The fluorescence quenching of the doubly charged quinine cation by Fe++, Ag+, and Br− was studied in the presence and absence of polyvinylsulfonate (PVS). The quenching by cationic species was greatly enhanced by PVS at low polyion concentrations; at higher concentrations of PVS, the fluorescence intensity increased owing to displacement of the quinine cations from the polyion domain. Quenching of quinine fluorescence by Br− was repressed by PVS. Interpretation of the data with the use of Fe++ as the quenching agent led to “effective concentrations” of counterions in the polyion domain similar to those calculated from the catalysis of the redox reaction of Co(NH3)5Cl++ with Fe++. This may indicate that the reagent ions are not rigidly bound to the polyion chain, since such binding would affect differently processes with high and low activation energies. The Stern‐Volmer constant for self‐quenching of the quinine fluorescence can also be obtained from fluorescence intensity data in PVS solution.

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