Confinement of chiral molecules in reverse micelles: FT-IR, polarimetric and VCD investigation on the state of dimethyl tartrate in sodium bis(2-ethylhexyl) sulfosuccinate reverse micelles dispersed in carbon tetrachloride

Abstract

a b s t r a c tThe state of d and l-dimethyl tartrate confined within dry sodium bis(2-ethylhexyl) sulfosuccinate (AOT) reverse micelles dispersed in CCl 4 has been investigated by FT-IR spectroscopy, polarimetry, and vibrational circular dichroism (VCD). Measurements have been performed at 25 • C as a function of the solubilizate-to-surfactant molar ratio (R) at a fixed AOT concentration (0.158 M). The analysis of experimental data is consistent with the hypothesis that both enantiomers of dimethyl tartrate are mainly entrapped in the reverse micelles and located in proximity to the surfactant head-group region. The formation of this interesting self-organized chiral nanostructure involves some changes of the typical H-bonding of dimethyl tartrates in the pure solid state or as monomers dispersed in CCl 4 attributable to the establishment of specific solubilizate/surfactant head-group interactions and confinement effects.

Measuring properties of interfacial and bulk water regions in a reverse micelle with IR spectroscopy: A volumetric analysis of the inhomogeneously broadened OH band

“…Recently, various treatments have been used to infer water intermolecular interactions and structure from the shape of the water OH band and its dependence on reverse micelle radius, e.g. Gaussian sub-band analysis [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] and time-resolved IR spectroscopy [18][19][20][21][22][23][24].…”

Chiroptical Phenomena in Reverse Micelles: The Case of (1R,2S)‐Dodecyl (2‐hydroxy‐1‐methyl‐2‐phenylethyl)dimethylammonium Bromide (DMEB)

“…The IR and VCD spectra in the mid‐IR region are reported in Figure for CCl 4 0.1 M solutions of DMEB and DMEB‐d 1 per se and with H 2 O or D 2 O, respectively (cases R = 0, 1, and 2). VCD, which has been established through the years as a powerful and reliable tool for configurational assignment together with DFT calculations, was also applied to study reverse micelles . It is also worth mentioning that VCD spectra for ephedra molecules had already been presented in the CH‐stretching region .…”

“…VCD, which has been established through the years as a powerful and reliable tool for configurational assignment together with DFT calculations, [24][25][26][33][34][35][36][37][38] was also applied to study reverse micelles. 22,23,39 It is also worth mentioning that VCD spectra for ephedra molecules had already been presented in the CH-stretching region. 40 In the SI file one may find our mid-IR VCD spectra of one of the ephedra molecules studied in previously 40 (MEPhe), whose mid-IR spectra was also presented 41 : in the SI we compare the VCD spectra of MEPhe and DMEB.…”

“…In the literature, chiroptical spectroscopies are useful to study chiral surfactants. 4,[18][19][20][21][22][23] The present study is based on the combined use of nuclear magnetic resonance (NMR), Fourier transform infrared (FT-IR), and vibrational circular dichroism (VCD) spectroscopy, as previously reported in the case of reverse micelles of soy lecithin and bis(2ethylhexyl) sulfosuccinate (AOT) in interaction with dimethyl tartrate molecules. 22,23 To gain insight into the observed VCD features, we added a preliminary Density Functional Theory (DFT) study [24][25][26][27] in the present work.…”

“…4,[18][19][20][21][22][23] The present study is based on the combined use of nuclear magnetic resonance (NMR), Fourier transform infrared (FT-IR), and vibrational circular dichroism (VCD) spectroscopy, as previously reported in the case of reverse micelles of soy lecithin and bis(2ethylhexyl) sulfosuccinate (AOT) in interaction with dimethyl tartrate molecules. 22,23 To gain insight into the observed VCD features, we added a preliminary Density Functional Theory (DFT) study [24][25][26][27] in the present work. The large number of atoms present in DMEB and its high conformational flexibility prompted us to use smaller model compounds with reduced number of atoms and conformations, but still sharing the "ephedra"-like characteristics: (1R,2S)-N-methylephedrine (with its enantiomer (1S,2R)-N-methyl-ephedrine) (MEPhe), and (1R,2S)-N,N-bis (methyl)-ephedrinium bromide (with its enantiomer (1S,2R)-N,N-bis (methyl)-ephedrinium bromide) (DMEPhe).…”