Photochemically Induced Ion Transfer

Considering the difficulties in measuring simple ion-transfer kinetics, photogeneration of ions close to the interface and observation of the photocurrent associated with their transfer was proposed. In this way, the interfadal polarization is kept quasi-constant, and the photocurrent does not suffer from the RC lime constant of the interface. This concept was pioneered by Kotov and Kuzmin that published a series of papers on the subject [143-146]. Two kinds of photochani-cal systems were used protoporphyrin (excitation 540-580 nm) quenched by quinones, and quinones (excitation 313-365 nm) quenched by telraphenylborale. Similarly, Samec et al. have studied photoinduced ion-transfer reactions nsing tetra-arylborate and tetra-arylarsonium as the chromophore, thereby generating the more hydrophilic bridged tetra-aryl intermediate [147,148]. 

From a mass transport viewpoint, the kinetics of the ion-transfer reactions can be obtained by solving the following differential equation  

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