Infrared spectroscopic study of the hydration of porous glass

1989 ◽  
Vol 54 (4) ◽  
pp. 878-891 ◽  
Author(s):  
Ondřej Ivanek ◽  
Pavel Schmidt ◽  
Bohdan Schneider
Keyword(s):  
Hydrogen Bonds ◽  
Spectroscopic Study ◽  
Infrared Spectra ◽  
Porous Glass ◽  
Glass Surface ◽  
Capillary Condensation ◽  
Water Molecules ◽  
Infrared Spectroscopic Study ◽  
Native State ◽  
Oh Groups

Infrared spectra of mesoporous and macroporous siliceous glasses were measured in the native state and after silylation, at various contents of H2O and D2O. By analysis of these spectra it was found that water is bound to the glass surface by strong hydrogen bonds between the water molecules and isolated Si-OH groups; capillary condensation was observed only in native mesoporous glasses.

scholarly journals Water Adsorption Properties of Free and Dehydrated β-Cyclodextrin Studied by near Infrared Spectroscopy and Gravimetry

2016 ◽  
Vol 689 ◽  
pp. 143-147 ◽  
Author(s):  
Alfred A. Christy
Keyword(s):  
Hydrogen Bonds ◽  
Infrared Spectra ◽  
Water Adsorption ◽  
Near Infrared ◽  
Adsorption Properties ◽  
Water Molecules ◽  
Hydroxyl Groups ◽  
Oh Groups ◽  
Near Infrared Spectra ◽  
Adsorption Of Water

β-cyclodextrin, like other carbohydrates has a tendency to adsorb water molecules and the properties are attributed to the hydroxyl groups in the molecules. β-cyclodextrin, the cyclic oligomer of glucose has a hydrophobic interior and hydrophilic exterior. The cyclic structure favours the formation of hydrogen bonds between the OH groups on the adjacent glucose units and affects the formation of hydrogen bonds with water molecules. The hydoxyl groups engaged in hydrogen bondings can be eliminated at high temperatures and the adsorption properties of the dehydrated β-cyclodextrin will depend on the new functional groups formed. The aim of the report is to discuss the issue of the water adsorption properties of free and dehydrated β-cyclodextrin. Dry β-cyclodextrin and dehydrated β-cyclodextrin at temperatures 250, 300 and 350 °C were allowed to adsorb water from a humidity controlled air environmennt and the evolving near infrared spectra were measured using a near infrared spectrometer equipped with a transflectance accessory. The near infrared spectra in the region 10,000-4000 cm-1 and their second and fourth derivative profiles were used in studying the variation in the adsorption characteristics of dehydrated β-cyclodextrin. The results of the analyses show that the adsorption of water by β-cyclodextrin decreses at 300 °C compared to 200 and 250 °C. Dehydration forms more of the ethereal type-O-bonds in the molecule and explains the decrease in the water molecular adsorption at higher dehydration temperatures.

Infrared spectroscopic study of the YPO4-YCrO4 system

1985 ◽  
Vol 50 (10) ◽  
pp. 2139-2145
Author(s):  
Alexander Muck ◽  
Eva Šantavá ◽  
Bohumil Hájek
Keyword(s):  
Spectroscopic Study ◽  
Infrared Spectra ◽  
Point Of View ◽  
Mixed Crystals ◽  
Crystal Symmetry ◽  
Infrared Spectroscopic Study ◽  
X Ray Diffraction ◽  
X Ray ◽  
Infrared Spectroscopic ◽  
Diffraction Patterns

The infrared spectra and powder X-ray diffraction patterns of polycrystalline YPO4-YCrO4 samples are studied from the point of view of their crystal symmetry. Mixed crystals of the D4h19 symmetry are formed over the region of 0-30 mol.% YPO4 in YCrO4. The Td → D2d → D2 or C2v(GS eff) correlation is appropriate for both PO43- and CrO43- anions.

A Raman and infrared spectroscopic study of triethylenediamine (DABCO) and its protonated forms

1988 ◽  
Vol 66 (5) ◽  
pp. 1249-1257 ◽  
Author(s):  
David A. Guzonas ◽  
Donald E. Irish
Keyword(s):  
Raman Spectrum ◽  
Spectroscopic Study ◽  
Infrared Spectra ◽  
Infrared Spectroscopic Study ◽  
Protonated Forms ◽  
Infrared Spectroscopic ◽  
Vibrational Bands

The Raman and infrared spectra of DABCO have been measured as a function of the pH, and the vibrational bands of the two protonated forms of DABCO have been tabulated and assigned. The frequencies of several of the Raman bands were found to exhibit substantial shifts upon protonation, and the appearance of the Raman spectrum in the region between 900 and 1100 cm−1 in particular shows differences which can be used to differentiate between the three forms of DABCO. The values of the two pKa's were determined from the intensity versus pH plots for the three species.

Infrared spectra of the interactions of aniline and porous glass surfaces

1969 ◽  
Vol 47 (8) ◽  
pp. 1281-1287 ◽  
Author(s):  
M. J. D. Low ◽  
V. V. Subba Rao
Keyword(s):  
Nitrogen Atom ◽  
Aromatic Ring ◽  
Secondary Amine ◽  
Infrared Spectra ◽  
Porous Glass ◽  
Weak Interactions ◽  
Amine Group ◽  
Oh Groups ◽  
Glass Surfaces ◽  
Adsorption And Dissociation

Infrared spectra were recorded of aniline sorbed on highly dehydroxylated, deuterated, and on fluoridated porous glass as well as on pure and boria-impregnated silica. The results suggest that two types of weak interactions involving the surface SiOH and B—OH groups occurred; the nitrogen atom of the amine was hydrogen bonded to surface OH and there was an interaction between OH groups and the π system of the aromatic ring. Some aniline chemisorbed on surface boron via the nitrogen atom of the amine group. Some aniline chemisorbed dissociatively to form secondary amine structures bonded through the nitrogen to surface boron atoms and new B—OH groups formed. Surface boron impurity acted as an adsorption and dissociation center.

A Raman and infrared spectroscopic study of compounds characterized by strong hydrogen bonds

1981 ◽  
Vol 73 (1) ◽  
pp. 19-29 ◽  
Author(s):  
Alessandro Bertoluzza ◽  
Patrizia Monti ◽  
Maria Antonietta Morelli ◽  
Maria Angela Battaglia
Keyword(s):  
Hydrogen Bonds ◽  
Spectroscopic Study ◽  
Infrared Spectroscopic Study ◽  
Infrared Spectroscopic

Infrared study of the interactions of acetone and siliceous surfaces

1969 ◽  
Vol 47 (14) ◽  
pp. 2545-2554 ◽  
Author(s):  
J. C. McManus ◽  
Yoshio Harano ◽  
M. J. D. Low
Keyword(s):  
Hydrogen Bonds ◽  
Carbonyl Group ◽  
Boron Atom ◽  
Porous Glass ◽  
Carbonyl Groups ◽  
Infrared Study ◽  
Oh Groups ◽  
Silica Surfaces ◽  
Surface Hydroxyls ◽  
Glass Surfaces

Adsorbed acetone is held to silica surfaces by hydrogen bonds between surface silanols and the acetone carbonyl groups. Acetone is adsorbed by this mechanism on porous glass surfaces but there is also some decomposition, as shown by the increase in surface B—OH groups and by formation of new C—H absorptions at 2984 and 2940 cm−1. Experiments with boron-impregnated silica indicated that the presence of boron in the porous glass can account for this decomposition process. Bands at 1660–1670 and 1650 cm−1, observed when acetone and acetone-d6, respectively, were adsorbed on either porous glass or boron-impregnated silica, are attributed to ν(C=O) of the carbonyl group coordinated with a surface boron atom. The surface hydroxyls of both silica and porous glass could exchange with the deuterium of acetone-d6 via a mechanism involving an enol intermediate.

Redetermination of rifampicin pentahydrate revealing a zwitterionic form of the antibiotic

2012 ◽  
Vol 68 (5) ◽  
pp. o209-o212 ◽  
Author(s):  
Barbara Wicher ◽  
Krystian Pyta ◽  
Piotr Przybylski ◽  
Ewa Tykarska ◽  
Maria Gdaniec
Keyword(s):  
Molecular Structure ◽  
Crystal Structure ◽  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Amide Group ◽  
Water Molecules ◽  
Acta Cryst ◽  
Oh Groups ◽  
Zwitterionic Form ◽  
The Family

Rifampicin belongs to the family of naphthalenic ansamycin antibiotics. The first crystal structure of rifampicin in the form of the pentahydrate was reported in 1975 [Gadret, Goursolle, Leger & Colleter (1975).Acta Cryst.B31, 1454–1462] with the rifampicin molecule assumed to be neutral. Redetermination of this crystal structure now shows that one of the phenol –OH groups is deprotonated, with the proton transferred to a piperazine N atom, confirming earlier spectroscopic results that indicated a zwitterionic form for the molecule, namely (2S,12Z,14E,16S,17S,18R,19R,20R,21S,22R,23S,24E)-21-acetyloxy-6,9,17,19-tetrahydroxy-23-methoxy-2,4,12,16,18,20,22-heptamethyl-8-[(E)-N-(4-methylpiperazin-4-ium-1-yl)formimidoyl]-1,11-dioxo-1,2-dihydro-2,7-(epoxypentadeca[1,11,13]trienimino)naphtho[2,1-b]furan-5-olate pentahydrate, C43H58N4O12·5H2O. The molecular structure of this antibiotic is stabilized by a system of four intramolecular O—H...O and N—H...N hydrogen bonds. Four of the symmetry-independent water molecules are arrangedviahydrogen bonds into helical chains extending along [100], whereas the fifth water molecule forms only one hydrogen bond, to the amide group O atom. The rifampicin molecules interactviaO—H...O hydrogen bonds, generating chains along [001]. Rifampicin pentahydrate is isostructural with recently reported rifampicin trihydrate methanol disolvate.

The Infrared Spectrum of Ethylene Oxide Clathrate Hydrate between 360 and 20 cm−1, at 100 °K

1972 ◽  
Vol 50 (21) ◽  
pp. 3443-3449 ◽  
Author(s):  
J. E. Bertie ◽  
D. A. Othen
Keyword(s):  
Hydrogen Bonds ◽  
Infrared Spectrum ◽  
Ethylene Oxide ◽  
Infrared Spectra ◽  
Far Infrared ◽  
Empirical Correlation ◽  
Strong Absorption ◽  
Water Molecules ◽  
Oxide Hydrate ◽  
Infrared Frequencies

The infrared spectra of authenticated samples of ethylene oxide hydrate and deuterate at 100 °K have been measured between 360 and 20 cm−1. The spectra confirm that the water molecules are orientationally-disordered and reorient slowly compared to far-infrared frequencies. An empirical correlation is suggested between the frequencies of strong absorption and the number of non-equivalent hydrogen bonds, their length and distribution. The contribution to the spectrum by the ethylene oxide intermolecular vibrations is discussed.

scholarly journals Porous Si Partially Filled with Water Molecules—Crystal Structure, Energy Bands and Optical Properties from First Principles

Nanomaterials ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 396
Author(s):  
Ya. Shchur ◽  
O. Pavlyuk ◽  
A.S. Andrushchak ◽  
S. Vitusevich ◽  
A.V. Kityk
Keyword(s):  
Optical Properties ◽  
Hydrogen Bonds ◽  
First Principles ◽  
Energy Band ◽  
Visible Range ◽  
Band Spectrum ◽  
Water Molecules ◽  
Hydroxyl Groups ◽  
Porous Si ◽  
Oh Groups

The paper reports the results on first-principles investigation of energy band spectrum and optical properties of bulk and nanoporous silicon. We present the evolution of energy band-gap, refractive indices and extinction coefficients going from the bulk Si of cubic symmetry to porous Si with periodically ordered square-shaped pores of 7.34, 11.26 and 15.40 Å width. We consider two natural processes observed in practice, the hydroxylation of Si pores (introduction of OH groups into pores) and the penetration of water molecules into Si pores, as well as their impact on the electronic spectrum and optical properties of Si superstructures. The penetration of OH groups into the pores of the smallest 7.34 Å width causes a disintegration of hydroxyl groups and forms non-bonded protons which might be a reason for proton conductivity of porous Si. The porosity of silicon increases the extinction coefficient, k, in the visible range of the spectrum. The water structuring in pores of various diameters is analysed in detail. By using the bond valence sum approach we demonstrate that the types and geometry of most of hydrogen bonds created within the pores manifest a structural evolution from distorted hydrogen bonds inherent to small pores (∼7 Å) to typical hydrogen bonds observed by us in larger pores (∼15 Å) which are consistent with those observed in a wide database of inorganic crystals.

Size-Resolved Infrared Spectroscopic Study of Structural Transitions in Sodium-Doped (H2O)n Clusters Containing 10–100 Water Molecules

2014 ◽  
Vol 119 (11) ◽  
pp. 2709-2720 ◽  
Author(s):  
Florian Zurheide ◽  
Christoph W. Dierking ◽  
Christoph C. Pradzynski ◽  
Richard M. Forck ◽  
Florian Flüggen ◽  
...  
Keyword(s):  
Spectroscopic Study ◽  
Water Molecules ◽  
Infrared Spectroscopic Study ◽  
Structural Transitions ◽  
Infrared Spectroscopic
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