Spectroelectrochemistry at the liquid|liquid interface: Parallel beam UV–vis absorption

We present two novel UV–vis absorption spectroelectrochemical cells for the study of electrochemical processes at polarized liquid|liquid interfaces based on the parallel incidence of the light beam with respect to the interface. The first one is a crude design (Cell 1) based on an existing cylindrical cell for liquid|liquid electrochemistry. The second design (Cell 2) is superior and based on the assembly of the four-electrode set-up inside a rectangular quartz spectrophotometric cuvette. In both cases it is demonstrated that absorption spectroelectrochemistry in parallel beam configuration can be a sensitive probe of processes such as ion transfer at the polarized liquid|liquid interface, if the contribution from the bulk of the sampled phase is removed. In particular, the electrochemical and spectroscopic performance of both cell designs was evaluated using the well-known transfer of Ru(bpy)32+ across the water|1,2-DCE interface as a model reaction.