Kinetic Studies of Ester Hydrolysis at Transition Metal Centers within Perfluorosulfonate Films

Abstract

The rates of ester hydrolysis at the ligands of two transition metal complexes have been measured in aqueous solution and for the Nafion‐incorporated complexes. Pseudofirst‐order rate constants for the base‐mediated hydrolysis of and (bpy = 2,2′‐bipyridyl; , ) were determined via ion‐pair HPLC and spectrophotometry in aqueous solution; the corresponding rates for the Nafion‐incorporated complexes were monitored via cyclic voltammetry. When the rate of hydrolysis within Nafion is similar to that in free solution. When the rate of hydrolysis within Nafion is similar to that in free solution. When , more complex behavior is observed: the hydrophobic osmium complex is electroinactive prior to hydrolysis of the ester linkage. After hydrolysis, the dicarboxylate is electroactive. The more hydrophilic ruthenium complex is electroactive when incorporated into Nafion, but the rate of ester hydrolysis is depressed ten‐fold relative to free solution. These results show that it is possible to design a molecule to partition into a specific domain of Nafion and to control its release into other domains. In this fashion Nanon might serve as a model system for biological studies.