A New Organized Media: Glycerol: N,N- Dimethylformamide Mixtures/AOT/ n -Heptane Reversed Micelles. The Effect of Confinement on Preferential Solvation

Abstract

In this work we investigate the behavior of theglycerol (GY):N,N-dimethylformamide (DMF) mixture inhomogeneous and sodium 1,4-bis(2-ethylhexyl)sulfosuccinate(AOT)/n-heptane reversed micelles (RMs) media. To achievethis goal we have used the solvatochromic behavior of 1-methyl-8-oxyquinolinium betaine (QB) as an absorption probe, anddynamic light scattering (DLS). QB shows strong preferentialsolvation when it is dissolved in the GY:DMF mixture, and, asQB is a good hydrogen bond acceptor molecular probe, it ispreferentially solvated by the GYDMF hydrogen-bonded(H-bonded) species. On the other hand, when the GY:DMFmixture was investigated in AOT RMs, the results show that themixture is encapsulated in the polar core of the AOT RMs. DLS confirms the formation of the GY:DMF/AOT/n-heptane RMs since an increase in theWs = ([GY] þ [DMF])/[AOT] values causes an increment in the RMs droplets sizes. The solvatochromic behavior of QB, which resides at the AOT RMs interface, shows that QB is mostly solvated by GY molecules, especially at low Ws values. Thus, it seems that upon encapsulation inside the polar core of the AOT RMs, the GYDMF interaction diminishes due to the strong AOTGY interaction. 1HNMR chemical shifts of GY and DMF measured in the different AOT RMs investigated showsthat GY and DMF behave practically as noninteracting solvents inside the RMs.