Dielectric Relaxation of Biological Water

Nandi, Nilashis; Bagchi, Biman

doi:10.1021/jp971879g

Cited by 459 publications

(612 citation statements)

References 55 publications

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“…However, as discussed below in connection with the analysis of the vibrational echo experiments, equilibration may slow substantially in the reverse micelles, in which case, the long time component of the decays in Figure 3 are a combination of heat flow and reequilibration. This picture of heat diffusion out of the reverse micelles, thereby causing the long-lived signal to decay, is consistent with observations of hydrogen-bond dissociation and reformation dynamics of methanol oligomers in CCl 4 . 78 It is interesting to contrast these results with those presented by Dlott and co-workers, 45 who examined the vibrational cascade of the excited OH stretch of H 2 O in AOT reverse micelles.…”

Section: Resultssupporting

confidence: 90%

“…Because the laser spectrum overlaps with absorption from CO 2 in the air, the experimental apparatus after the generation of mid-IR pulses was purged with CO 2 scrubbed air. To determine the pulse duration in the sample, the three time-delayed mid-IR pulses that are used in the experiment are cross-correlated in a nonresonant sample that contains only CCl 4 . All of the beams pass through the identical amount of optical material.…”

Section: Methodsmentioning

confidence: 99%

“…32,33 Aspects of the dynamics of AOT reverse micelles have been explored by various techniques. The dielectric response of AOT reverse micelles in CCl 4 and n-heptane have examined in the 0.01-20 GHz range. 34 The authors have attributed the observed 100 MHz relaxation (10 ns) to a combination of two diffusion mechanisms: reorientation of the reverse micelle and the "free" diffusion of completely hydrated AOT ion pairs.…”

Section: Introductionmentioning

confidence: 99%

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Dynamics of Nanoscopic Water: Vibrational Echo and Infrared Pump−Probe Studies of Reverse Micelles

2005

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The dynamics of water in nanoscopic pools 1.7-4.0 nm in diameter in AOT reverse micelles were studied with ultrafast infrared spectrally resolved stimulated vibrational echo and pump-probe spectroscopies. The experiments were conducted on the OD hydroxyl stretch of low-concentration HOD in the H 2 O, providing a direct examination of the hydrogen-bond network dynamics. Pump-probe experiments show that the vibrational lifetime of the OD stretch mode increases as the size of the reverse micelle decreases. These experiments are also sensitive to hydrogen-bond dissociation and reformation dynamics, which are observed to change with reverse micelle size. Spectrally resolved vibrational echo data were obtained at several frequencies. The vibrational echo data are compared to data taken on bulk water and on a 6 M NaCl solution, which is used to examine the role of ionic strength on the water dynamics in reverse micelles. Two types of vibrational echo measurements are presented: the vibrational echo decays and the vibrational echo peak shifts. As the water nanopool size decreases, the vibrational echo decays become slower. Even the largest nanopool (4 nm, ∼1000 water molecules) has dynamics that are substantially slower than bulk water. It is demonstrated that the slow dynamics in the reverse micelle water nanopools are a result of confinement rather than ionic strength. The data are fit using time-dependent diagrammatic perturbation theory to obtain the frequency-frequency correlation function (FFCF) for each reverse micelle. The results are compared to the FFCF of water and show that the largest differences are in the slowest time scale dynamics. In bulk water, the slowest time scale dynamics are caused by hydrogen-bond network equilibration, i.e., the making and breaking of hydrogen bonds. For the smallest nanopools, the longest time scale component of the water dynamics is ∼10 times longer than the dynamics in bulk water. The vibrational echo data for the smallest reverse micelle displays a dependence on the detection wavelength, which may indicate that multiple ensembles of water molecules are being observed.

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Section: Resultssupporting

confidence: 90%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Dynamics of Nanoscopic Water: Vibrational Echo and Infrared Pump−Probe Studies of Reverse Micelles

2005

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“…In bulk water, solvation is essentially complete after 1 ps, 48,49 but water in confined environments gives rise to slower solvation response, 49,50 which has been argued to arise from a dynamic equilibrium between bound and free water molecules. [51][52][53][54][55][56] (We do not, however, subscribe to the idea of "biological water", which some of these latter references argue for. 57 ) Consequently, we suggest that the water responsible for the relatively rapid solvation response in the micelles is colocalized in the Stern layer with C153.…”

Section: Discussionmentioning

confidence: 99%

Dynamic Solvation in Phosphonium Ionic Liquids: Comparison of Bulk and Micellar Systems and Considerations for the Construction of the Solvation Correlation Function, C(t)

et al. 2008

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Dynamic solvation of the dye coumarin 153 is studied in a phosphonium ionic liquid: hexadecyltributylphosphonium bromide, [(C4)3C16P+][Br-]. It forms micelles in water, and the bulk also exists as a liquid under our experimental conditions. This system permits a comparison with an imidazolium ionic liquid studied earlier, which also formed micelles in water (J. Phys. Chem. A 2006, 110, 10725−10730). We conclude that our analysis of the comparable situation in a phosphonium liquid is not as definitive as we had proposed earlier, i.e., that the majority of the early-time solvation arises from the organic cation. Part of the difficulty in performing this analysis is most likely due to the amount of water that is associated with the micelle. In the course of this work, we have focused on the calculation of the solvation correlation function, C(t), and investigated how it depends upon the methods with which the "zero-time" spectrum is constructed. Arlington, Box 19065, Arlington, Texas 76019 ReceiVed: NoVember 8, 2007; In Final Form: December 7, 2007 Dynamic solvation of the dye coumarin 153 is studied in a phosphonium ionic liquid: hexadecyltributylphosphonium bromide, [(C 4 ) 3 C 16 P + ][Br -]. It forms micelles in water, and the bulk also exists as a liquid under our experimental conditions. This system permits a comparison with an imidazolium ionic liquid studied earlier, which also formed micelles in water (J. Phys. Chem. A 2006, 110, 10725-10730). We conclude that our analysis of the comparable situation in a phosphonium liquid is not as definitive as we had proposed earlier, i.e., that the majority of the early-time solvation arises from the organic cation. Part of the difficulty in performing this analysis is most likely due to the amount of water that is associated with the micelle. In the course of this work, we have focused on the calculation of the solvation correlation function, C(t), and investigated how it depends upon the methods with which the "zero-time" spectrum is constructed. Keywords

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“…Compared with bulk water, the strong HB water of hydration water was achieved at the cost of intermediate HB water species. This ''intermediate / strong HB transition'' trend represents the strengthening of HBs (112,113), and such a strengthened HB is considered to force water molecules to undergo slower reorientational motion (114,115). Additionally, we found a slight decrease in the weak HB species for hydration water (though the variation is within the margin of error), which is in line with a reduction of NHB water around albumin.…”

Section: Hydrogen-bond Strengthmentioning

confidence: 99%

Hydrogen Bond Network of Water around Protein Investigated with Terahertz and Infrared Spectroscopy

Shiraga

Ogawa

Kondo

2016

Biophysical Journal

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The dynamical and structural properties of water at protein interfaces were characterized on the basis of the broadband complex dielectric constant (0.25 to 400 THz) of albumin aqueous solutions. Our analysis of the dielectric responses between 0.25 and 12 THz first revealed hydration water with retarded reorientational dynamics extending~8.5 Å (corresponding to three to four layers) out from the albumin surface. Second, the number of nonhydrogen-bonded water was decreased in the presence of the albumin solute, indicating protein inhibits the fragmentation of the water hydrogen-bond network. Finally, water molecules at the albumin interface were found to form a distorted hydrogen-bond structure due to topological and energetic disorder of the protein surface. In addition, the intramolecular O-H stretching vibration of water (~100 THz), which is sensitive to hydrogen-bond environment, pointed to a trend that hydration water has a larger population of strongly hydrogen-bonded water molecules compared with that of bulk water. From these experimental results, we concluded that the ''strengthened'' water hydrogen bonds at the protein interface dynamically slow down the reorientational motion of water and form the less-defective hydrogen-bond network by inhibiting the fragmentation of water-water hydrogen bonds. Nevertheless, such a strengthened water hydrogen-bond network is composed of heterogeneous hydrogen-bond distances and angles, and thus characterized as structurally ''distorted.''

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Dielectric Relaxation of Biological Water

Cited by 459 publications

References 55 publications

Dynamics of Nanoscopic Water: Vibrational Echo and Infrared Pump−Probe Studies of Reverse Micelles

Dynamics of Nanoscopic Water: Vibrational Echo and Infrared Pump−Probe Studies of Reverse Micelles

Dynamic Solvation in Phosphonium Ionic Liquids: Comparison of Bulk and Micellar Systems and Considerations for the Construction of the Solvation Correlation Function, C(t)

Hydrogen Bond Network of Water around Protein Investigated with Terahertz and Infrared Spectroscopy

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