RAMAN-spektroskopische Untersuchungen zur Hydratation polarer Molekülverbindungen

Carius, W.; Möckel, K.; Schröter, O.; Thomzik, D.

doi:10.1515/zpch-1982-0126

Cited by 6 publications

(8 citation statements)

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“…Concentration dependences of the ν a (CD) and ν s (CD) for DMSO- d 6 /H 2 O mixtures were also measured as plotted as a function of X H2O in Figure (B) and the wavenumber of the SO stretching mode, ν(SO), for DMSO/H 2 O mixtures is shown in Figure (C). The ν a (CH) and ν s (CH), abbreviated as ν(CH) below, and ν a (CD) and ν s (CD) denoted as ν(CD) below, increase with increasing water fraction, while ν(SO) decreases as previously reported in the Raman study . The redshift in ν(SO) is attributed to a hydrogen-bonding interaction of the SO oxygen with water.…”

Section: Resultssupporting

confidence: 69%

“…Carius et al observed that the vibrational frequencies of the Raman bands characteristic of the strong polar groups of acetone, dimethyl sulfoxide (DMSO), and hexamethylphosphoricacidtriamide (HMPT) show a drastic decrease with increasing water concentrations, whereas the ν(CH) values increase monotonically . They reported also that the shifts of ν(CH) are dependent on the polarity of the polar group of acetonitrile, acetone, THF, DMF, DMSO, and HMPT.…”

Section: Introductionmentioning

confidence: 99%

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Hydration of the CH Groups in Dimethyl Sulfoxide Probed by NMR and IR

Mizuno¹,

Imafuji²,

Ochi³

et al. 2000

J. Phys. Chem. B

161

144

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1H and 13C NMR of dimethyl sulfoxide (DMSO)/H2O mixtures were measured, together with the IR of DMSO/D2O mixtures, to study the effect of the polar SO group on hydration of the CH groups. Chemical shifts were determined by the external double reference method, which provides the in situ volume magnetic susceptibility indispensable to the correction of the chemical shifts. The chemical shift of the water protons as the measure of the polarization of the water in the mixtures, δ H 2O, increases from 3.6 ppm at the water mole fraction X H2O = 0.05 to 4.8 ppm, the value for pure water, at X H2O = 0.80. It exceeds 4.8 ppm in the region of X H2O > 0.80 at 23.3 °C, indicating the presence of anomalously polarized water molecules, so-called hydrophobic hydration. The frequencies of the CH stretching vibration bands for (DMSO)/D2O mixtures, ν(CH), increase with increasing X D2O, implying the progressive depolarization and contraction of the CH bonds. ν(CH) values take maxima at X D2O = 0.96. The chemical shift of the CH proton increases very slightly with increasing X H2O, whereas that of the CH carbon decreases, suggesting the polarization of the CH bonds contrary to the depolarization in them as shown by the blueshifts of the ν(CH) values. The pushball hydration model previously presented is applied to interpret the results; the electron of CH hydrogen is pushed toward the carbon atom due to dispersion interaction with the electrons of water oxygen. The pushing effect probed by the blueshifts of ν(CH) can be related to the increase in the polarization of the water molecules probed by δ H 2O. The redshifts in ν(CH) in the water rich extreme may be ascribed to a partial polarization of the CH bond resulting from hydrogen bonding interaction with highly polarized water molecules, in addition to the dispersion interaction. The role of the SO group in the hydration of the CH groups is discussed in comparison with the roles of the hydrophilic groups of acetone and tert-butyl alcohol.

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Section: Resultssupporting

confidence: 69%

Section: Introductionmentioning

confidence: 99%

Hydration of the CH Groups in Dimethyl Sulfoxide Probed by NMR and IR

Mizuno¹,

Imafuji²,

Ochi³

et al. 2000

J. Phys. Chem. B

161

144

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“…Carius et al observed that the Raman ν(C-H)'s for acetone, dimethyl sulfoxide, and hexamethylphosphoricacidtriamide exhibit blue shifts with increasing water concentrations, in contrast to the red shifts of the stretching bands for polar groups. 31 Thomzik et al obtained similar results for n-propylamine, piperidine, morpholine, and 1,4-dioxane to those obtained by Carius et al 32 The blue shift in the ν(C-H) is contrary to what can be expected for the solvation of a C-H group by water acting as a polar solvent. The blue shift cannot be considered to be a result of conventional hydrogen-bonding interaction between the polar group and water either, because such an interaction would result in a red shift in the ν(C-H) according to the conventional hydrogen bond concept.…”

Section: Introductionsupporting

confidence: 56%

“…Raman, IR, and NMR are useful techniques to experimentally obtain atomic-level descriptions to assess the roles of polar groups in the solvation of hydrophobic moieties of organic solutes in water. Carius et al observed that the Raman ν(C−H)'s for acetone, dimethyl sulfoxide, and hexamethylphosphoricacidtriamide exhibit blue shifts with increasing water concentrations, in contrast to the red shifts of the stretching bands for polar groups . Thomzik et al obtained similar results for n -propylamine, piperidine, morpholine, and 1,4-dioxane to those obtained by Carius et al The blue shift in the ν(C−H) is contrary to what can be expected for the solvation of a C−H group by water acting as a polar solvent.…”

Section: Introductionmentioning

confidence: 67%

Hydration of the CH Groups in 1,4-Dioxane Probed by NMR and IR: Contribution of Blue-Shifting CH···OH₂ Hydrogen Bonds

Mizuno¹,

Imafuji²,

Fujiwara³

et al. 2003

J. Phys. Chem. B

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H NMR and IR studies were carried out for 1,4-dioxane/H 2 O mixtures over the whole concentration range at temperatures of 1, 25, and 50 °C. 1 H NMR spectra were also acquired for 1,3-dioxane/H 2 O and 4-methyl-1,3-dioxane/H 2 O mixtures. All the chemical shift data were measured by referring to an external reference and corrected using in situ bulk susceptibilities as determined on a unified scale. The results are compared with those previously obtained for dimethyl sulfoxide/H 2 O and acetone/H 2 O mixtures in order to determine the influence of the polar group on the hydrogen bond formation of water at the polar and hydrophobic groups. It was found that an anomalous polarization of the water molecules, which had been observed in the dimethyl sulfoxide/H 2 O and acetone/H 2 O mixtures, did not occur in the three different aqueous dioxane mixtures. Thus, we have concluded that the hydrophobic moiety in an organic solute having a polar group does not play a role in anomalously high polarization of the water molecules. We have also concluded that the hydrogen-bonding basicity of the polar group is an important factor for the anomalous polarization of the water in the water-rich region and that the basicities of the ether oxygens in the three dioxanes are not strong enough to cause the anomalous polarization of water. It was found that the frequencies of IR C-H stretching vibration modes of 1,4-dioxane increase and the absorption intensities of the modes decrease with increasing water concentration. Since these spectroscopic features correspond well to the formation of the blue-shifting C-H‚‚‚OH 2 hydrogen bonds obtained from ab initio calculations for complexations in gas phases, we can categorize the solvation of the C-H groups in the dioxanes in aqueous solutions as blue-shifting C-H‚‚‚O hydrogen bonding. Thus, we propose for the first time that the hydration of CH groups in organic solutes having a polar group is due to the formation of blue-shifting C-H‚‚‚OH 2 hydrogen bonds. As a picture of the hydration of the C-H groups in 1,4-dioxane, we propose the formation of a bifunctional hydrogen-bonded hydration complex in which each water molecule plays a role as both a proton donor in the conventional O-H‚‚‚O hydrogen bonding with the ether oxygen and a proton acceptor in the blue-shifting C-H‚‚‚O hydrogen bonding simultaneously.

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“…The hydration of alkyl groups of various water-soluble systems surprisingly is accompanied by a C-H stretch frequency increase instead of the expected frequency decrease. This was observed experimentally for dimethyl sulfoxide (DMSO), hexamethylphosphoricacidtriamide, acetonitrile, acetone, THF, DMF and HMPT, 1 n-propylamine, piperidine, morpholine and 1,4-dioxane, 2 ethanol, 3 and phosphocholine. 4 The hydration of DMSO, yielding a red shift of the SdO stretch frequency and a blue shift of the C-H stretch frequencies, was studied using IR and NMR spectroscopy.…”

Section: Introductionmentioning

confidence: 53%

Hydration of Sulfo and Methyl Groups in Dimethyl Sulfoxide Is Accompanied by the Formation of Red-Shifted Hydrogen Bonds and Improper Blue-Shifted Hydrogen Bonds: An ab Initio Quantum Chemical Study

Mrazkova

Hobza

2003

J. Phys. Chem. A

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In this study, the hydration of dimethyl sulfoxide was investigated by means of molecular dynamics (MD) simulations and quantum chemical correlated ab initio calculations. MD simulations show the hydration sites when the systems are exposed to 1, 3, 6, 16, and 32 water molecules. Various DMSO‚‚‚(H 2 O) n (n ) 1-3) complexes where waters hydrate sulfo and methyl groups were then reoptimized at the ab initio level. The hydration of DMSO leads to an elongation of the SdO bond and a contraction of methyl C-H bonds. Whereas the elongation of the SdO bond is accompanied by a red shift of the respective stretch frequency, the contraction of the C-H bonds gives a blue shift to the C-H stretch frequencies. The former effect is easily explained by the transfer of electron density to the antibonding orbitals of the SdO bond, yielding its weakening. Various mechanisms leading to the contraction of the methyl CH bonds were suggested. They were based on secondary geometry changes originating from the significant elongation of the SdO bond and also on the changes of the electron density in DMSO upon complexation, resulting in a rehybridization of the CH bonds. The influence of the electrostatic field of hydrating waters was also considered. Predicted frequency shifts fully agree with the observed data. Also, the observed blue shift increase occurring as a consequence of progressive hydration was interpreted theoretically, and the mechanisms of this phenomenon are suggested.

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RAMAN-spektroskopische Untersuchungen zur Hydratation polarer Molekülverbindungen

Cited by 6 publications

References 0 publications

Hydration of the CH Groups in Dimethyl Sulfoxide Probed by NMR and IR

Hydration of the CH Groups in Dimethyl Sulfoxide Probed by NMR and IR

Hydration of the CH Groups in 1,4-Dioxane Probed by NMR and IR: Contribution of Blue-Shifting CH···OH₂ Hydrogen Bonds

Hydration of Sulfo and Methyl Groups in Dimethyl Sulfoxide Is Accompanied by the Formation of Red-Shifted Hydrogen Bonds and Improper Blue-Shifted Hydrogen Bonds: An ab Initio Quantum Chemical Study

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RAMAN-spektroskopische Untersuchungen zur Hydratation polarer Molekülverbindungen

Cited by 6 publications

References 0 publications

Hydration of the CH Groups in Dimethyl Sulfoxide Probed by NMR and IR

Hydration of the CH Groups in Dimethyl Sulfoxide Probed by NMR and IR

Hydration of the CH Groups in 1,4-Dioxane Probed by NMR and IR: Contribution of Blue-Shifting CH···OH2 Hydrogen Bonds

Hydration of Sulfo and Methyl Groups in Dimethyl Sulfoxide Is Accompanied by the Formation of Red-Shifted Hydrogen Bonds and Improper Blue-Shifted Hydrogen Bonds: An ab Initio Quantum Chemical Study

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Hydration of the CH Groups in 1,4-Dioxane Probed by NMR and IR: Contribution of Blue-Shifting CH···OH₂ Hydrogen Bonds