Infrared studies of DNA, water, and inositol associations

1968 ◽  
Vol 46 (7) ◽  
pp. 691-695 ◽  
Author(s):  
S. J. Webb ◽  
J. S. Bhorjee
Keyword(s):  
Infrared Spectra ◽  
Water Molecules ◽  
Large Decrease ◽  
Bacterial Dna ◽  
Dichroic Ratio ◽  
Biological Phenomena ◽  
Oriented Films ◽  
Infrared Studies

Ultraviolet and polarized infrared spectra of oriented films of bacterial DNA have been recorded over a range of relative humidities (R.H.) between 10 and 84%. The films were made from a DNA gel in H2O or D2O with and without 5% (w/v) myo-inositol. In the absence of inositol a large decrease in the dichroic ratio at 1670 cm−1 occurred as the R.H. was lowered between 70 and 30%, indicating the occurrence of considerable disorganization. This was not observed when the DNA was dehydrated in the presence of myo-inositol. A marked increase in absorbance at 2600 Å which occurred on lowering the R.H. from 70 to 50% was prevented also by inositol.These results indicate that myo-inositol can replace water molecules and maintain the DNA in the B configuration during dehydration. The possible significance of these observations in the explanation of certain biological phenomena is discussed.

Infrared Studies of Water in Crystalline Hydrates: Sodium Nitroprusside Dihydrate, Na2[Fe(CN)5NO]•2H2O

1971 ◽  
Vol 49 (9) ◽  
pp. 1413-1424 ◽  
Author(s):  
Michaela Holzbecher ◽  
Osvald Knop ◽  
Michael Falk
Keyword(s):  
Water Molecule ◽  
Sodium Nitroprusside ◽  
Infrared Spectra ◽  
Structure Determination ◽  
The Other ◽  
Water Molecules ◽  
Infrared Studies ◽  
Increasing Temperature ◽  
Crystalline Hydrates ◽  
The Ideal

Infrared spectra of polycrystalline Na2[Fe(CN)5NO] 2H2O at different degrees of deuteration were studied as a function of temperature. The single peaks observed for the bending fundamentals of isotopically dilute H2O and D2O show that all the water molecules are equivalent, as required by Manoharan and Hamilton's structure determination; the doublets observed for the three fundamentals of isotopically dilute HDO show that the water molecules are asymmetric. Doublet separation decreases gradually with increasing temperature, indicating decreasing asymmetry. The water molecule appears to orient itself so as to maximize the strength of one [Formula: see text] bond, while the other OH group interacts only very weakly with another CN group. The hitherto unknown extent to which the nitroprusside ion deviates from the ideal C4v symmetry has been estimated from the 13C14N stretching spectrum. The 15N16O and 14N18O stretching spectrum was used to confirm that only one type of NO group is present in the crystal, and hence that all nitroprusside ions are equivalent.

Raman and Infrared Studies of Hexa-, Tetra-, and Dihydrates of Crystalline Magnesium Nitrate

1973 ◽  
Vol 51 (1) ◽  
pp. 118-125 ◽  
Author(s):  
Tien-Chung Godfrey Chang ◽  
Donald E. Irish
Keyword(s):  
Water Content ◽  
Infrared Spectra ◽  
Magnesium Nitrate ◽  
Octahedral Coordination ◽  
Water Molecules ◽  
Nitrate Ions ◽  
Infrared Studies

Raman and infrared spectra of Mg(NO3)2•6H2O, Mg(NO3)2•6D2O and partially dehydrated products have been obtained and assigned. As the water content is reduced a different set of lines appears and maximizes at the composition Mg(NO3)2 4H2O On further dehydration a third set of lines characteristic of Mg(NO3)2•2H2O appears. The existence of the metastable tetrahydrate had not been confirmed since it was reported in 1932. The spectra suggest that four equatorial sites aroung Mg2+ in the tetrahydrate are occupied by four water molecules and two axial sites by nitrate ions, oriented in monodentate fashion. The spectra suggest that in the dihydrate approximately octahedral coordination is maintained by having two nitrate ions oriented in bidentate fashion and two water molecules trans to each other on the remaining sites.

Infrared Studies of Water in Crystalline Hydrates: K2FeCl5·H2O (Erythrosiderite) and Related Aquopentachloroferrates(III)

1975 ◽  
Vol 53 (1) ◽  
pp. 51-57 ◽  
Author(s):  
Michael Falk ◽  
Chung-Hsi Huang ◽  
Osvald Knop
Keyword(s):  
Water Molecule ◽  
Infrared Spectra ◽  
Water Molecules ◽  
High Charge ◽  
Infrared Studies ◽  
Approximate Location ◽  
Crystalline Hydrates

Infrared spectra of M2[FeCl5(H2O)] (M = K, Rb, NH4) at different degrees of deuteration were recorded, between 4000 and 300 cm−1, at 30 and −160 °C. The spectra of the three compounds were closely similar, as was that of natural K2[FeCl5(H2O)] (erythrosiderite). They indicate the existence of only one type of water molecule in the structure. The water molecules are symmetric, well separated from one another, and engage in O—H … Cl bonds with O … Cl distances of about 3.22 Å, as estimated from the OH and OD stretching frequencies. These conclusions support the structure proposed for K2[FeCl5(H2O)] by Bellanca and lead to approximate location of the H atoms. The observed mixing of the librational and translational modes, which occurs when the frequencies of translational modes are high, may be characteristic of H2O molecules coordinated to cations of high charge.

scholarly journals INFRARED SPECTRA OF THIOSACCHARINATES OF CADMIUM AND LEAD COMPARISON WITH THE ANALOGOUS METAL SACCHARINATES

2017 ◽  
Vol 27 (1-2) ◽  
Author(s):  
Gligor Jovanovski ◽  
Adnan Kahil ◽  
Orhideja Grupče
Keyword(s):  
Infrared Spectra ◽  
Room Temperature ◽  
Spectral Characteristics ◽  
Crystalline Hydrate ◽  
Water Molecules ◽  
X Ray ◽  
Weak Hydrogen Bonds ◽  
Deuterated Analogue ◽  
The Fourier Transform ◽  
Cadmium And Lead

A b s t r a c t: The Fourier transform (FT) infrared spectra of thiosaccharinates of cadmium and lead in the 4000–400 cm–1 region were studied. Although the observed resemblance between the spectra recorded in KBr pellets suggests a possible similarity between their structures as well, the powder X-ray diagrams show that these two compounds are not isomorphous. The presence of broad and intense bands in the region of the HOH stretchings shows that thiosaccharinate of cadmium is a crystalline hydrate and the spectral picture in the region of the O-D stretchings of the isotopically isolated HOD molecules in the partially deuterated analogue indicates that present in its structure are at least two types of crystallographically different water molecules involved in the formation of weak hydrogen bonds. The room temperature (RT) spectrum of lead thiosaccharinate in the region of the ν(HOH) modes differs significantly from the spectrum recorded at the boiling temperature of liquid nitrogen (LNT), which may perhaps be interpreted as an indication that a phase transition is taking place on lowering the temperature. The spectrum of lead thiosaccharinate was recorded in a Nujol mull as well. While the KBr and Nujol spectra are essentially identical in the region below 1600 cm–1, no bands are observed in the HOH stretching region of the mull spectra. In fact, it was shown that the appearance of the spectra of lead thiosaccharinates depends on the emulsion preparation rate. A comparison of the spectral characteristics of the thiosaccharinates of cadmium and lead with those of the corresponding saccharinates (their crystal structures are known) was made, special attention being paid to the analysis of the SO2 stretching region in the saccharinate and thiosaccharinate compounds.

The Far Infrared Spectra of Partially Orientationally Ordered Water Molecules: Hexamethylenetetramine Hexahydrate at 95 K

1975 ◽  
Vol 53 (17) ◽  
pp. 2642-2645 ◽  
Author(s):  
John E. Bertie ◽  
Marco Solinas
Keyword(s):  
Infrared Spectrum ◽  
Infrared Spectra ◽  
Far Infrared ◽  
Clathrate Hydrate ◽  
Factor Group ◽  
Water Molecules ◽  
Disordered Solids ◽  
Ordered Water ◽  
Far Infrared Spectra ◽  
Three Phases

The far infrared spectra of four isotopic modifications of the partially orientationally ordered clathrate hydrate hexamethylenetetramine hexahydrate at 95 K are reported. The spectra are assigned to absorption allowed under the diffraction factor group, and to disorder-allowed absorption, following the theory for absorption by translational vibrations in orientationally disordered solids. Three phases formed primarily by hydrogen-bonded water molecules are known to be significantly, but only partially, orientationally ordered, hexamethylenetetramine hexahydrate, ice V, and ice VI. Of these phases, only ice VI fails to show sharp absorption in its far infrared spectrum in addition to the broad, disorder-allowed absorption.

Low-temperature infrared studies of some acid–base reactions

1983 ◽  
Vol 61 (9) ◽  
pp. 2077-2088 ◽  
Author(s):  
Theresa Huston ◽  
I. C. Hisatsune ◽  
Julian Heicklen
Keyword(s):  
Hydrogen Bonding ◽  
Infrared Spectroscopy ◽  
Low Temperature ◽  
Infrared Spectra ◽  
Acid Base ◽  
Reaction Systems ◽  
Solid States ◽  
Infrared Studies

Low-temperature infrared spectroscopy has been used to examine the systems NH3 + H2O, NH3 + HCl, H2O + HCl, NH3 + HNO3, and NH2OH + HNO3. Hydrogen-bonding in the solid states greatly reduces the reactivities in these systems. Temperatures where reactions initiated in the systems NH3(s) + HCl(g), HNO3(s) + NH3(g), H2O(s) + HCl(g), and NH2OH(s) + HNO3(s) were, respectively, −145, −130, −127, and −125 °C. Infrared spectra of 2NH3•H2O, NH3•H2O, NH4Cl•3NH3, NH4NO3•3NH3, NH4NO3•2HNO3, NH2OH2+NO3−, NH3OH+NO3−, H3O+Cl−, H5O2+Cl−, and H5O2+Cl−•H2O have been identified in these reaction systems.

Infrared spectra of tautomers and rotamers of 9-methylguanine. An experimental and theoretical study

1991 ◽  
Vol 69 (11) ◽  
pp. 1705-1720 ◽  
Author(s):  
K. Szczepaniak ◽  
M. Szczesniak ◽  
W. Szajda ◽  
W. B. Person ◽  
J. Leszczynski
Keyword(s):  
Absorption Spectrum ◽  
Ab Initio ◽  
Infrared Spectra ◽  
Electronic Absorption ◽  
Ab Initio Calculation ◽  
Theoretical Study ◽  
Free Energies ◽  
Argon Matrix ◽  
Tautomeric Forms ◽  
Infrared Studies

Both amino-oxo and amino-hydroxy tautomeric forms of 9-methylguanine have been identified in approximately equal abundance in. infrared studies of these molecules isolated in the hydrophobic environment of an argon matrix at 12 K. The amino-hydroxy tautomer occurs in two different rotamers correlated with the rotation of the OH group. The ratio of concentrations of the two rotamers is sensitive to UV irradiation, and this ratio then relaxes to an equilibrium value after irradiation is stopped. This sensitivity allows us to separate the experimental spectra related to the oxo tautomer and to each of the rotamers of the hydroxy tautomer. The relative concentrations of the amino-oxo and amino-hydroxy tautomers ([a-o]/[a-h] = K(o-h) = 1.0 ± 0.3) and of the two rotamers (K(h1-h2) = 0.31 ± 0.10 in an argon matrix at 12 K and about 30 ± 15 in the vapor at 470 K) are estimated from the observed relative infrared absorbances. From these relative concentrations the differences between the free energies of the tautomers (ΔG470 (o-h) = 0 ± 0.5 kJ mol−1) and of the two rotamers (ΔG(h1-h2) = 0.12 ± 0.03 kJ mol−1 in the argon matrix at 12 K and ΔG470 between +2 and −13 kJ mol−1 in the vapor at 470 K) have been estimated. The electronic absorption spectrum of 9-methylguanine isolated in the argon matrix at 12 K and the effect of brief ultraviolet irradiation on it have also been studied. In an effort to interpret the experimental results, ab initio calculations of the infrared spectra have been made for 9-methylguanine at the 3-21G//3-21G level. Comparison with the experimental spectra is of some help with the assignment of the infrared spectra for the different tautomers. Key words: 9-methylguanine, tautomerism, infrared and ultraviolet spectra, matrix isolation, ab initio calculation.

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.

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