Hydrogen bonded structure of water and aqueous solutions of sodium halides: a Raman spectroscopic study

doi:10.1016/j.molstruc.2004.07.016

Journal of Molecular Structure

Volume 707, Issues 1–3, 22 November 2004, Pages 83-88

https://doi.org/10.1016/j.molstruc.2004.07.016 Get rights and content

Abstract

The OH stretching (2500–4000 cm⁻¹) Raman spectra from pure water and sodium halides solutions are obtained. The Raman contours are deconvoluted with five Gaussian components that their center frequencies are 3051, 3233, 3393, 3511 and 3628 cm⁻¹, respectively. From the Raman spectra and their deconvolutions similarities and differences of the effects of temperature and sodium halides on hydrogen bond structure of water are shown clearly. Like temperature, all of sodium halides break tetrahedral structure of water, and the Gaussian component of 3233 cm⁻¹ decreases and the components of 3393 and 3511 cm⁻¹ increase basically. The differences lie in their effects on the component 3051 and 3628 cm⁻¹. All of halogenic ions break tetrahedral structure of water and their breaking actions are in the order of F⁻¹<Cl⁻¹<Br⁻¹<I⁻¹. The reason is relative to the strength of halogenic ion–water and water–water hydrogen bonds.

Introduction

Water, the most abundant and usual liquid on the earth, have many unique properties that play an essential role in biological and chemical reactions. All of the unique properties relate to water structure, which has been studied in theory and experiment extensively [1]. However, aspects of water structure still remain uncertain [2], [3], [4].

Liquid water appears to possess tetrahedral hydrogen bonded structure like the structure of ice. Temperature and ions are two common factors that influence the water structure and have been studied largely [1], [5], [6], [7], [8], [9]. Generally, water structure is broken with increasing temperature. Ions may have similar perturbing effects on water structure to the temperature, and even the concept of ‘structure temperature’, which defines the temperature at which pure water would have the same properties as those of a given solution, was used [10]. However, the differences between the effects of temperature and ions on water structure are rarely shown clearly.

The ions can be classified as ‘structure maker’ or ‘structure breaker’ [10]. And the effect of ion on water structure is ion-specific [11]. Many recent researches on the effects of ions on water structure were still using the concept [13], [14], though one research recently showed that ions does not lead to an enhancement and breakdown of the hydrogen-bond network in liquid [12].

Halogenic ions have played an important role in opening out the effects of anions on water structure [15], [16]. Usually in the halogenic ion, the F⁻ is regarded as structure maker and the others are structure breaker [10], [17]. Whereas, the effects of halogen ions on water structure are still in dispute. For example, some considered Cl⁻ as structure breaker [18], [19], [20], and the others thought of Cl⁻ as structure maker [21], [22]. So it is important to study interactions of halogenic ion and water molecules and to tell apart their effects on water structure in detail.

Vibrational spectroscopy is a powerful tool for studying water structure, as vibrational spectra are sensitive to local environmental of the molecule [6], [23], [24]. Raman spectroscopy is one of vibrational spectroscopy and has proven valuable in studying water structure [25], [26], [27], [28]. In the Raman spectrum of water, the O–H stretching band in the region of 2800–3800 cm⁻¹ is the most informative about water structure. Nevertheless, the contour of the O–H stretching band is broad and complex, and it is difficult to get information of water structure from the band directly.

Gaussian analysis is usually used to analyze the O–H stretching band for more information of water structure [18], [23], [29], [30]. It has as many as five stretching distributions, and usually is deconvoluted into 5, 4, 3, or 2 Gaussian components according to specific scheme used for analysis and designation [30]. For the five Gaussian fit, each Gaussian component indicates special configuration of water structure, and usually the two higher wavenumber components refer to water molecules whose hydrogen bonds have been broken in part or in whole, and the other three lower wavenumber components refer to fully hydrogen bonded water molecules [18], [30], [31], [32]. The content of the integrated intensity of one Gaussian component in the whole integrated intensity of the spectrum can be considered as concentration of configuration of water relative to the Gaussian component in the whole water. The 4, 3, or 2-Gaussian fits are a convenient substitute and approximation for the more elaborate five Gaussian fit [29].

In this study, the OH stretching (2500–4000 cm⁻¹) Raman spectra of pure water in the temperature range of 273–373 K and sodium halide solutions in the concentration of 0–1.0 mol/l are present. And the spectra are analyzed with five Gaussian fit that the center frequencies of the five components are 3051, 3233, 3393, 3511 and 3628 cm⁻¹, respectively. The effects of temperature and sodium halides on water structure are displayed in detail, and the similarities and differences of them can be deduced. The interactions of halogenic ion with water molecules also can be shown.

Section snippets

Experimental

The sodium halides used in this study are analytical grade reagents without further purification. The used water is ultra pure and has resistivity of about 18.0 MΩ cm. Total organic carbon and dissolved oxygen of the water are below 1.0 and 5.0 ppb, respectively. The concentration of solution is expressed in mol/l.

The Raman spectra are recorded with microscopic confocal Raman spectrometer (RM 2000). The band resolution is 1 cm⁻¹. The excitation wavelength is 514.5 nm, and the output laser power is

Temperature dependence of Raman spectrum of pure water

Fig. 1 shows the OH stretching (2500–4000 cm⁻¹) Raman spectra of pure water in the temperature range 273–373 K. It can be seen from the Raman spectra contour of water that the highest peak occurs near 3420±20 cm⁻¹, an intense shoulder occurs near 3230±20 cm⁻¹, and a weak shoulder is evident near 3620±20 cm⁻¹. With increasing temperature, the position of the highest peak shifts to high wavenumber, and the intensity of the intense shoulder decreases and the weak shoulder increases.

In order to get more

Conclusions

For five-component Gaussian deconvolution of Raman spectra of water, component 3051 and 3233 cm⁻¹ can been assigned to fully four-hydrogen bonded water molecules, component 3393 and 3511 cm⁻¹ to partly hydrogen bonded water molecules, and component 3628 cm⁻¹ to free water molecules or free OH.

The similarities and differences exist among the effects of temperature and sodium halides on structure of water. Both temperature and sodium halides break tetrahedral structure of water and conduce component

Acknowledgements

This work was supported by National Natural Science Foundation of China (No. 50238020) and Fundamental Research Fund of Tshinghua University and Analytical Fund of Tshinghua University.

References (36)

F. Franks
(1972)
S.R. Elliott
J. Chem. Phys.
(1995)
E. Schwegler et al.
Phys. Rev. Lett.
(2000)
M.C.R. Symons
Chem. Br.
(1989)
G.E. Walrafen
J. Chem. Phys.,
(1966)
D.E. Hare et al.
J. Chem. Phys.
(1990)
Y. Ikushima et al.
J. Chem. Phys.
(1998)
G.E. Walrafen
J. Chem. Phys.
(1962)
W. Martens et al.
J. Raman Spectrosc.
(2003)
F. Franks
(1972)

R. Leberman et al.

Nature

(1995)

A.W. Omta et al.

Science

(2003)

T. Chen et al.

J. Phys. Chem. A

(2003)

A. Chandra et al.

J. Phys. Chem. B

(2002)

S.R. Dillon et al.

J. Phys. Chem. A

(2002)

A. Chandra

J. Phys. Chem. B

(2003)

P.-A. Bergstrom et al.

J. Phys. Chem.

(1991)

F. Rull

Pure Appl. Chem.

(2002)

Cited by (122)

Molecular dynamics simulations and FTIR spectroscopy investigations on the hydration, transport, and dielectric properties of the NaF<inf>(aq)</inf> system at various concentrations
2024, Chemical Physics Impact
Sodium fluoride has many applications in various fields, such as dentistry, geochemistry, and rechargeable battery technology. Indeed, the determination of the hydration structures, dynamics, and dielectric properties of the NaF electrolyte in aqueous solutions is a crucial element in order to optimize its performance and predict its intervention mechanisms in industrial processes. In this study, we used the molecular dynamics approach to study the NaF_(aq) binary system at different concentrations ranging from 0.1 to 1.0 mol.kg⁻¹ using the OPLS-AA force field combined with the extended simple point load water model (SPC/E). Thus, the ions were represented as charged Lennard-Jones particles. The radial distribution functions (RDF) have been calculated to analyze the hydration shell structures of different ion pairs. The microstructures, self-diffusion coefficient, and dielectric constant were determined by molecular dynamics at various concentrations. Moreover, our FTIR spectroscopy data confirm the results obtained from molecular simulations.
Clay nanoflakes and organic molecules synergistically promoting CO<inf>2</inf> hydrate formation
2023, Journal of Colloid and Interface Science
Carbon dioxide (CO₂) reduction is an urgent challenge worldwide due to the dramatically increased CO₂ concentration and concomitant environmental problems. Geological CO₂ storage in gas hydrate in marine sediment is a promising and attractive way to mitigate CO₂ emissions owning to its huge storage capability and safety. However, the sluggish kinetics and unclear enhancing mechanisms of CO₂ hydrate formation limit the practical application of hydrate-based CO₂ storage technologies. Here, we used vermiculite nanoflakes (VMNs) and methionine (Met) to investigate the synergistic promotion of natural clay surface and organic matter on CO₂ hydrate formation kinetics. Induction time and t₉₀ in VMNs dispersion with Met were shorter by one to two orders of magnitude than Met solution and VMNs dispersion. Besides, CO₂ hydrate formation kinetics showed significant concentration-dependence on both Met and VMNs. The side chains of Met can promote CO₂ hydrate formation by inducing water molecules to form a clathrate-like structure. However, when Met concentration exceeded 3.0 mg/mL, the critical amount of ammonium ions from dissociated Met distorted the ordered structure of water molecules, inhibiting CO₂ hydrate formation. Negatively charged VMNs can attenuate this inhibition by adsorbing ammonium ions in VMNs dispersion. This work sheds light on the formation mechanism of CO₂ hydrate in the presence of clay and organic matter which are the indispensable constituents of marine sediments, also contributes to the practical application of hydrate-based CO₂ storage technologies.
Spatial homogeneity of pH in aerosol microdroplets
2023, Chem
Acidity plays a key role in atmospheric aerosol formation and strongly influences aerosols’ effects on air quality, climate, and the ecosystem. Fundamental questions about aerosol pH are, however, still under debate: how does the pH of aerosol microdroplets compare to that of the parent bulk solution, and do stable pH gradients exist within these microdroplets? Here, by using advanced single-particle and hyperspectral Raman microscopies, we directly measure the pH distribution in NaH₂PO₄-Na₂HPO₄ microdroplets (7–10 μm in radius) produced with the conjugate acid-base pair of H₂PO₄⁻-HPO₄²⁻. We show that the pH values of the investigated microdroplets are indistinguishable from the parent bulk solutions of the same electrolyte concentration and that the pH is essentially constant across the microdroplets, with standard deviations below 0.2 pH units. Similar results are observed for acidic NaHSO₄ microdroplets. Our findings are essential to understanding atmospheric multiphase chemistry and overall reactions and processes occurring in aqueous microdroplets.
Study of microwave non-thermal effects on hydrogen bonding in water by Raman spectroscopy
2023, Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy
Microwave chemistry plays an important role in organic synthesis. It has been debatable whether or not there are microwave non-thermal effects. Through analyzing the Raman spectra of pure water under two different heating methods (oil bath and microwave), the existence of microwave non-thermal effect is verified in this paper. The findings demonstrate that temperature has a significant impact on the Raman shift of the OH stretching band, which shifts to a high wave number as temperature rises and deforms the hydrogen bond (HB) network structure. Because microwave electric fields selectively heat water molecules (polar molecules) and destroy hydrogen bond structures in water, results in microwave heating more severe destruction of fully hydrogen-bonded structure than oil bath and transforms it more quickly into the partially hydrogen-bonded and free H₂O structure. Under the non-thermal effects of microwaves, hydrogen bonds that initially existed as stable tetrahedral structures are transformed into chain-like structures more rapidly. By comparing the Raman shift, it can be found that the microwave non-thermal effect can affect the hydrogen bonding in water for a long time (>1h). This study provides an experimental basis for enriching the mechanism of microwave non-thermal effects on hydrogen bonding.
The water structure around chloride ion investigated from D<inf>2</inf>O ↔ H<inf>2</inf>O substitution effect
2022, Journal of Molecular Liquids
The Raman spectra for (D₂O + H₂O) − NaCl solutions (n_H2O/n_D2O = 0/1, 1/4, 1/1, 4/1 and 1/0) were measured at temperatures from 293 to 573 K. We further discuss the water structure in the solutions based on the solute-correlated (SC) OD/OH stretch bands obtained from the Multivariate Curve Resolution method. The most prominent effect of H ↔ D substitution is raising the relative intensity of the high-wavenumber modes. The ∼ 2660 cm⁻¹/∼3635 cm⁻¹ mode can become the main peak when isotopic substitution ratio is 80 % at temperatures over 493 K. The spectral features suggest a flexible water structure in the Cl⁻ hydration shell where most hydrating water molecules are engaged in hydrogen bonding configurations of single donor (SD) and single hydrogen-bond water (SHW). The increase of isotopic substitution ratio leads to the structural transition of SD → SHW → FW (free water) so that FW is greatly increased at isotopic substitution ratio of 80 % and temperatures over 493 K. Moreover, the estimated hydrogen bond number for hydrating water indicates a stronger D₂O − Cl⁻ interaction than H₂O − Cl⁻ interaction in the hydration shell.
Perturbative vibration of the coupled hydrogen-bond (O:H–O) in water
2022, Advances in Colloid and Interface Science
Perturbation Raman spectroscopy has underscored the hydrogen bond (O:H–O or HB) cooperativity and polarizability (HBCP) for water, which offers a proper parameter space for the performance of the HB and electrons in the energy-space-time domains. The OO repulsive coupling drives the O:H–O segmental length and energy to relax cooperatively upon perturbation. Mechanical compression shortens and stiffens the O:H nonbond while lengthens and softens the HO bond associated with polarization. However, electrification by an electric field or charge injection, or molecular undercoordination at a surface, relaxes the O:H–O in a contrasting way to the compression with derivation of the supersolid phase that is viscoelastic, less dense, thermally diffusive, and mechanically and thermally more stable. The HO bond exhibits negative thermal expansivity in the liquid and the ice-I phase while its length responds in proportional to temperature in the quasisolid phase. The O:H–O relaxation modifies the mass densities, phase boundaries, critical temperatures and the polarization endows the slipperiness of ice and superfluidity of water at the nanometer scale. Protons injection by acid solvation creates the H↔H anti-HB and introduction of electron lone pairs derives the O:⇔:O super-HB into the solutions of base or H₂O₂ hydrogen-peroxide. The repulsive H↔H and O:⇔:O interactions lengthen the solvent HO bond while the solute HO bond contracts because its bond order loss. Differential phonon spectroscopy quantifies the abundance, structure order, and stiffness of the bonds transiting from the mode of pristine water to the perturbed states. The HBCP and the perturbative spectroscopy have enabled the dynamic potentials for the relaxing O:H–O bond. Findings not only amplified the power of the Raman spectroscopy but also substantiated the understanding of anomalies of water subjecting to perturbation.

View all citing articles on Scopus

View full text

Hydrogen bonded structure of water and aqueous solutions of sodium halides: a Raman spectroscopic study

Abstract

Introduction

Section snippets

Experimental

Temperature dependence of Raman spectrum of pure water

Conclusions

Acknowledgements

J. Chem. Phys.

Phys. Rev. Lett.

Chem. Br.

J. Chem. Phys.,

J. Chem. Phys.

J. Chem. Phys.

J. Chem. Phys.

J. Raman Spectrosc.

Nature

Science

J. Phys. Chem. A

J. Phys. Chem. B

J. Phys. Chem. A

J. Phys. Chem. B

J. Phys. Chem.

Pure Appl. Chem.