Millimeter Absorption Spectroscopy of Aqueous Systems

Khurgin, Yuri I.; Kudryashova, V. A.; Zavizion, V. A.; Бецкий, О. В.

doi:10.1002/9780470141465.ch6

Cited by 6 publications

(10 citation statements)

References 40 publications

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“…δα is equal to zero only if solutes do not modify water structure in their hydration shells. The absorption was proportional to the concentration of the free water, the fraction of water molecules that can freely rotate at considerable angle 6. The contributions to the absorption by both the solute itself and the bound water were significantly less than that for the free water 6.…”

Section: Resultsmentioning

confidence: 94%

“…Absorption of electromagnetic radiation α was equal to –log( I / I o ), where I o is the intensity of the applied radiation, and I is the intensity of radiation after passing through the solution. The hydration effect was assessed as the difference δα between the theoretical contribution of the aqueous component k 1 C 1 and the absorption of the solution α exp using the equation: where k 1 is the extinction coefficient of the pure water 6 . δα is equal to zero only if solutes do not modify water structure in their hydration shells.…”

Section: Resultsmentioning

confidence: 99%

“…Previously, absorption millimeter spectroscopy (AMS) was engaged for the direct measurements of absorption coefficients for solutions and thereby for the determinations of the hydration numbers of solutes 6. Absorption millimeter spectroscopy is able to determine the fraction of water molecules that are involved in the rotational motions (water dipole reorientational motions at significant angles) according to the wait‐and‐switch model 7.…”

Section: Introductionmentioning

confidence: 99%

“…These rotations are possible because of the reduction in the activation barrier for water dipole rotations owing to the interaction of a water molecule with the additional neighboring water molecule (fifth neighbor in the random tetrahedral network of hydrogen bonds). The hydration parameters were estimated from the deficit of absorption, the difference in absorption between undisturbed water and water with the solute, as it was attributed to the solute‐induced reduction in water mobility 6. The hydration number, N , was introduced as the number of the water molecules in the hydration shells for which the rotational mobility in the time scale of 10–50 ps was lost owing to the presence of the solute 6.…”

Section: Introductionmentioning

confidence: 99%

“…The hydration parameters were estimated from the deficit of absorption, the difference in absorption between undisturbed water and water with the solute, as it was attributed to the solute‐induced reduction in water mobility 6. The hydration number, N , was introduced as the number of the water molecules in the hydration shells for which the rotational mobility in the time scale of 10–50 ps was lost owing to the presence of the solute 6. The method of waveguide dielectric resonance (WDR) is a modification of millimeter spectroscopy allowing determination of hydration parameters at low concentrations up to 2–5 g · L −1 8.…”

Section: Introductionmentioning

confidence: 99%

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Hydration Characterization of Hydrophobically Modified Polymers by Dielectric Measurements in the Millimeter Range

Vorob’ev

Churochkina

Khokhlov

et al. 2007

Macromolecular Bioscience

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Bound water molecules, the fraction of water molecules that are present in the hydration shells of polymers, lose their rotational mobility in the time scale of 10-50 ps, leading to additional ordering compared with unperturbed water. The amount of bound water per number of carbons in the nonpolar groups as measured by the method of waveguide dielectric resonance increased in the following order: hydrophobically modified chitosan < globular protein < hydrophobically modified polyacrylamide. The hydrophobic modification of acrylamide and chitosan polymers gave smaller variation in hydration than did both the coil-to-globule transition of poly(N-isopropylacrylamide) and the masking of nonpolar groups within the protein globule.

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Section: Resultsmentioning

confidence: 94%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Hydration Characterization of Hydrophobically Modified Polymers by Dielectric Measurements in the Millimeter Range

Vorob’ev

Churochkina

Khokhlov

et al. 2007

Macromolecular Bioscience

View full text Add to dashboard Cite

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Quantitative evaluation of hydrophobic hydration of amphiphilic molecules and proteins by millimeter spectroscopy

Vorob’ev

1999

Spectroscopy of Biological Molecules: New Directions

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Study of intermolecular interactions in aqueous solutions by millimeter spectroscopy

1997

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The absorption of millimeter electromagnetic radiation (v = 1.4, 1.71, and 5 cm -1) by aqueous solutions of ~ycine (pH 6.t--6.2) in the concentration range of 0.5--2.5 tool L -1 was measured. It was found that the absorbing ability of the water present in the solutions, is higher than that of pure water. This phenomenon is explained by the presence of a center of negative hydration in the structure of the glycine zwitterion, which results in an increase in the rotational mobility of water molecules immobilized in the hydrate shell of the glycine zwitterion.Key words: glycine zwitterion, negative and positive hydration, aqueous solution, absorption of millimeter radiation.The biological rote of c~-amino acids evokes great interest in the molecular mechanisms of their interaction with an aqueous medium. In an aqueous medium at neutral pH values, c~-amino acids exist in the form of NH3+CHRCOO -zwitterions. Both charged groups can play the role of centers of the formation of H bonds with water molecules. The comparatively short distance between the withdrawing and donating centers is noticeably reflected in the acid-base and other physicochemical properties of a-amino acids. In particular, the IR spectra in the overtone region showed the formation of a stable I : 1 a-amino acid--water molecular complex, z The authors of this work assumed that in these complexes, a water molecule simultaneously forms two H bonds with the donor and acceptor groups of the a-amino acid, respectively. This mechanism of complex formation was not confirmed either in other experimental studies, or in a simulation of the hydration of glycine by the Monte-Carlo method. 3 Ab initio quantum-mechanical calculations of the glycine--water system showed, however, that this complex can exist. 4To obtain additional information on the character of intermolecular interactions of water molecules with the zwitterion of an cL-amino acid, we used absorption millimeter spectroscopy (AMS). The AMS experiment and its interpretation are considered in detail in Ref. 5. In this review, in particular, some problems that appear in the study of the hydration of c~-amino acids are discussed.The absorption of millimeter (MM) radiation by aqueous systems is a smooth function of frequency. Nevertheless, the AMS method allows one to study the action of a dissolved substance on the aqueous component of the solution, detecting the number of water molecules that change their dynamic state in the hydrate shell of the dissolved substance. 5 ExperimentalThe absorption coefficient* ct (dB mm -1) of the MM radiation (1.4--5 cm -l) of aqueous solutions of glycine (pH 6.1--6.2; C 2 = 0.5--2.5/mol L -l) was measured on quasioptical and waveguide type setups in ceils with variable thickness. 5 The absorption =exp (~ < 0.003) was measured at a frequency of 5 cm -1 at 20 and 60 ~ measurements at frequencies of 1.71 and 1.40 cm -1 were performed only at 20 ~ Bidistilled water and twice recrystallized glycine (Reanal) were used for the preparation of solutions. Results and DiscussionAs ...

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Millimeter Absorption Spectroscopy of Aqueous Systems

Cited by 6 publications

References 40 publications

Hydration Characterization of Hydrophobically Modified Polymers by Dielectric Measurements in the Millimeter Range

Hydration Characterization of Hydrophobically Modified Polymers by Dielectric Measurements in the Millimeter Range

Quantitative evaluation of hydrophobic hydration of amphiphilic molecules and proteins by millimeter spectroscopy

Study of intermolecular interactions in aqueous solutions by millimeter spectroscopy

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