Strongly polarized water at the interfacial region in reversed micelles containing 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecanenickel(II) as a probe

Abstract

The change in the polarization of water in sodium bis(2-ethyl-1-hexyl)sulfosuccinate (AOT) reversed micelles has been investigated spectrophotometrically using 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecanenickel(II) cation, [Ni(tmc)]²⁺, as a probe of electron-pair acceptance. Although above a water-to-AOT molar ratio (R) of 10 the spectrum of [Ni(tmc)]²⁺ is very similar to that in bulk water, below R= 10 the peaks of the five-coordinated complex shift to longer wavelengths and at R≈ 1 the spectrum is very similar to that of the hydroxide ion-coordinated complex. This shows that a decrease in the R value obviously leads to a gradual increase in the polarization of water coordinated to [Ni(tmc)]²⁺ owing to the cooperative influence of the sulfo ion of AOT and [Ni(tmc)]²⁺ through hydrogen bonding at the water/surfactant interface.