Measurements of Non-Equilibrium State for Reactions at Liquid-Liquid Interfaces and the Analysis of Selective Distribution Behaviors

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As measurement methods for reactions at liquid-liquid interfaces, the resonat second harmonic (RSH) spectroscopy and the time resolved total internal reflection fluorescence spectroscopy (TIRF) were developped and applied to characterize molecules absorbed at liquid-liquid interfaces. In addition, the potential-scan polarography with an electrolyte dropping electrode was developped for the analysis of the complexation kinetics at liquid-liquid interfaces.As for RSH spectroscopy, rhodamine B (Rh-B) is studied as a moleule adsorbed at liquid-liquid interfaces. Rh-B molecules were found to be stabilized at the heptane-water interface compared bulk solutions. Based on the concentration dependence of RSH spectra, it was found that molecules at the interface can exist as a mixture of monomer and dimer when the bulk concentration is high. Molecular orientations of Rh-B were estimated and the orientation angle was almost constant as 65 degree when the concentration is low, and the angle decrea … More sed at higher concentrations.A time resolved TIRF was applied to study the microenvironments of 8-anilino-1-naphthalenesulfonate molecules at the heptane-water interface. By analysing the fluorescence decay profiles, it was found that the fluorophores in the vicinity of the interface are present in two different solvated structures. One of them is located up to a few nanometers from the interface, and the other is located in a relatively wide range twoard the aqueous phase. The former solvated structure is the cause of a long fluorescence lifetime which reflects the low polarity or the extremely high viscosity of the microenvironments.As for chemical reactions at liquid-liquid interfaces, complexation kinetics were examined using 8-quinolinol derivatives and divalent metal ions by measuring dynamic interfacial tension and ion transfer across the interface. As a result, it was found that 5-octyloxymethyl-8-quinolinol showed interface absorptivity and the adorptivity depended on both the counter anion and the organic phase. These dependence was explained by the ion pair formation constant and the distribution coefficient of a chelating reagent. From the measurement of an ion tranfer across the interface, it was suggested that the complexations occured at the interface nearer to the organic phase.As mentioned above, several methods were establishied to analyze reactions at liquid-liquid interfaces, and the reactions at the interface were found to be different from those in bluk solutions. Less