IR Study of Hydrogen Bonds in Halogenoalcohol−Water Mixtures

Abstract

The IR bending vibrational (ν2) band of the water molecules in aqueous haloethanol (XCH2CH2OH; X = Cl, Br, I) mixtures has been studied, and the haloethanols are found to give rise to red shifts of the ν2 band. Since the frequency of the ν2 band is reciprocally proportional to the hydrogen-bonding strength of water molecules, the results lead us to a conclusion that a breakdown of water structure occurs in the mixtures. The red shifts occur gradually in the whole range of the haloethanol concentrations, showing gradual breakdown of the water structure with an increase in the alcohol concentration. The effect of the alcohols on the red shift is found to be in the order ClCH2CH2OH < BrCH2CH2OH < ICH2CH2OH. The red shifts are discussed in comparison with the blue shifts of the ν2 band previously observed for the aqueous ethanol mixtures. The conclusion is consistent with that of the 1H-NMR studies of the same mixtures in which the water structure is discussed in terms of the chemical shift of the water proton.

Variation in Fourier Transform Infrared Spectra of Some Homeopathic Potencies and Their Diluent Media

“…The number of observed v 2 bands should provide the number of water species with different hydrogen-bonding strengths. 6 There may be a few more water species than those actually observed by v 2 bands in the spectra. According to Mizuno (personal communication, June 2003), IR spectroscopy has superior power in that different water species are distinctive from each other, but it is very difficult to resolve the curve into components.…”

“…Among these methods, infrared (IR) spectroscopy is one of the most promising for the study of the distribution of hydrogen-bonding strengths of the water molecules in the mixtures because of the short time scale of measurements. 6 There are two kinds of fundamental vibrations for molecules: (1) stretching, in which the distance between two atoms increase or decrease but the atom remains in the same bond axis; and (2) bending, in which the position of the atom changes relative to the original bond axis. Infrared radiation causes vibrational excitation of the molec-ular framework of a compound.…”

“…In the region of bending vibrational band of water (v 2 ), alcohols have no absorption bands. 6 The purpose of the present work is to study v 2 bands through Fourier transform infrared (FTIR) spectroscopy in 90% ethanol, Ethanol 30C, and some potentized drugs such as Nux vomica 30C, Lycopodium 30C, Santonin 30C, Cina 30C, Cina 206C, and Cina 1006C prepared in 90% ethanol. Conventionally vibrations are labeled in decreasing frequency within their symmetry type.…”

In situ study of diffusion and interaction of water and electrolyte solution in polyacrylonitrile (PAN) membrane using FTIR and two-dimensional correlation analysis

“…The existence of these asynchronous bands reveals that during water diffusion the broad water stretching vibration at 3700-3000 cm À1 is split into three separate bands located at 3618, 3560 and 3373 cm À1 , respectively, which overlap in the 1D-IR spectra. As is well known, the water molecules form hydrogen bonds, the water OH stretching vibration band will shift to a lower wavenumber compared to that of free water [32,33]. Thus, the band appears at 3373 cm À1 due to the n as mode of strongly hydrogen-bonded water molecules [29]; the absorption band at 3560 cm À1 is the vibrations of moderately hydrogen-bonded water molecules with -CN group in PAN; the band at 3618 cm À1 is assigned to the vibrations of weakly hydrogen-bonded water molecules with -CN group in PAN.…”

Experimental observations on the competing effect of tetrahydrofuran and an electrolyte and the strength of hydrate inhibition among metal halides in mixed CO2 hydrate equilibria

“…This is the main mechanism of the ambient water structure breakdown although a dipole-dipole interaction between the halogen atoms and the surrounding water molecules is responsible for the breakdown as well [21]. The study of IR measurements for the same (water + halogenated alcohol) mixtures [23] indicates conclusively that a breakdown of water structure occurred in the (water + halogenated alcohol) mixtures and the effects of the alcohols on the breakdown is found to increase in the order ClC 2 H 4 OH < BrC 2 H 4 OH < IC 2 H 4 OH.…”