ABSTRACT
In 1989, a review with the same title was published in this series [1]. Indeed, at that time, electrochemistry at polarized liquid-liquid interfaces had undergone a second youth with the pioneering work of C. Gavach et al. in France and J. Koryta, Z. Samec et al. in what was then Czechoslovakia, and M. Senda et al. in Japan. A legacy of J. Koryta is the acronym that is now widely used even outside the chemistry community, namely, ITIES, which stands for Interface between Two Immiscible Electrolyte Solutions [2]. This first review, written in two parts, respectively, in 1985 and 1989, was dedicated first to a historical perspective dating back to the end of the nineteenth century, to a presentation of the thermodynamics of interfacial polarization, including electrocapillary phenomena, and to an introduction to the different charge transfer processes, namely, ion-transfer, assisted-ion-transfer, and electron-transfer reactions. The key advantage in preparing a second review nearly two decades later is to realize the extent of many developments that have in fact taken place during this period. Indeed, in 1989, we had very little information on the interface structure apart from that derived from thermodynamic analyses-no molecular dynamics yet, no x-ray reflectivity yet, and no surfacesensitive spectroscopic techniques yet. In fact, it sounds like 1989 was a very long time ago. For ion-transfer reactions, it is clear that the rate constants reported over the years have increased regularly as the methods and instrumentation have improved, yielding better-quality data, but more important, new theories have been developed that shed a new light on the reaction mechanism. In the field of assisted-ion-transfer reactions, a major development has been the concept of ionic partition diagrams that is widely used to report the lipophilicity, that is, the logP, of ionizable molecules, particularly those of therapeutic importance. From a technological viewpoint, one can cite the introduction of micro-ITIES that can now be used in conjunction with Scanning Electrochemical Microscopy (SECM), and, of course, the development of a full range of spectroelectrochemical techniques such as voltabsorptometry, voltfluorimetry, potential-modulated absorbance and fluorescence, and nonlinear optical methods.
