Vibrations Of OH Groups Research Articles

CRYPTOMELANE MODIFIED WITH TRANSITION METAL IONS: STRUCTURE AND CATALYTIC ACTIVITY IN THE REACTION OF OZONE DECOMPOSITION

Cryptomelane, OMS-2, and cryptomelane modified with transition metal ions, M/OMS-2 (M = Cu2+, Co2+, Fe3+), were synthesized by the reaction of KMnO4 reduction with manganous salts (MnCl2 and MnSO4) by the reflux method. The samples thus synthesized were characterized by X-ray diffraction and IR spectroscopic methods and their catalytic activity was tested in the reaction of ozone decomposition. Cryptomelane, OMS-2, is the main phase of the synthesized samples, bixbyite, Mn2O3, and pyrolusite, β-MnO2, are impurity phases presented in OMS-2 and M/OMS-2 at a quantity lower than 10 %. The doped metal ions did not create a new phase however they influenced the size of cryptomelane crystallites and it became almost two times lower. Our IR spectral investigations show that, in the region of stretching vibrations of OH groups in the associated water molecules, the IR absorption is very weak for all M/OMS-2 samples as opposed to OMS-2. IR spectroscopic analysis also showed that incorporation of the transition metal ions into the cryptomelane structure differently affected the vibrations of Mn-O and Mn-OH bonds. The doped Cu2+ ion practically caused no change in the OMS-2 spectrum whereas new absorption bands characteristic of Co-O and Fe-O bonds appeared in the spectra of Co/OMS-2 and Fe/OMS-2. The absorption band in 650-400 cm-1 region of the Fe/OMS-2 spectrum is complex. The catalytic activity of M/OMS-2 samples depended on the nature of the current transition metal ion doped into tunnel channels of cryptomelane. The Cu/OMS-2 sample exhibits a tendency to the steady-state mode of ozone decomposition whereas, in the case of the Cu/OMS-2 and Fe/OMS-2, the ozone concentration at the reactor outlet rapidly increases. Comparison of the activity of these three M/OMS-2 samples and OMS-2 resulted in the following order: Co/OMS-2 > OMS-2 > Cu/OMS-2 > Fe/OMS-2. Thus, the accelerating effect was observed only in the case of cobalt (II) ions.

Yellow and blue emission from BaO-(ZnO/ZnF2)[sbnd]B2O3[sbnd]TeO2 glasses doped with Dy3+ for laser medium and scintillation material applications

Barium zinc oxide and barium zinc oxyfluoride borotellurite glass doped with Dy3+ have been comparatively investigated on physical, structural, optical and luminescence properties. Both glasses were prepared by melt and quenching technique. The FTIR spectra show weaker vibration of OH group in Dy3+ doped oxyfluoride glass than oxide glass due to fluoride existence. It results to stronger 4f-4f transition of oxyfluoride than oxide glass. The highest absorption band centered at 1269 nm of both glasses corresponds to 6H15/2 → 6F11/2 transition of Dy3+. The prepared glasses were excited by photon with 388 nm and emitted white light due to the integration of strong yellow 575 nm (4F9/2 → 6H13/2) and blue 482 nm (4F9/2 → 6H15/2) emission. X-ray luminescence also were affeted from less vibration of OH group in oxyfluoride glass and showed similar strong emission pattern to the photoluminescence spectra. The calculations of radiative properties were done by Judd-Ofelt theory. The oxyfluoride glass showed more asymmetry of Dy3+ environment with higher J-O parameter (Ω2) value than oxide glass. The radiative transition probability (AR), stimulated emission cross-sections (σ) and branching ratios (βR) of oxyfluoride glass were higher than oxide glass which perform lower laser threshold and higher gain laser application. Both glasses in this work performed the high potential for photonic applications, but addition of fluoride made barium zinc oxyfluoride borotellurite glass more suitable than barium zinc oxide borotellurite glass for usage as a scintillation, laser medium and other white-light photonic material.

Concentration dependences of IR absorption spectra in the range of stretching vibrations of OH groups of congruent lithium-niobate crystals doped with zinc and magnesium

The concentration behavior of the parameters of spectral lines that correspond to stretching vibrations of OH groups in the IR absorption spectra of LiNbO3:Zn (0.04–4.46 mol % ZnO) and LiNbO3:Mg (0.19–5.91 mol % MgO) crystals has been studied. It has been found that, in the range of threshold concentrations of Zn2+ and Mg2+ doping cations, the line parameters experience a jump. In this case, the widths of some lines decrease, which indicates the ordering of OH groups in the crystal. It has been shown that nonstoichiometric crystals are characterized by the occurrence of different positions of OH groups and different values of the quasi-elastic constants of O–H bonds in the crystal structure. In the stoichiometric LiNbO3 crystal, all the positions of OH groups are the same, and the quasi-elastic constants of O–H bonds are identical.

EFFECT OF THE NATURE OF SYNTHETIC SUPPORTS ON THE GEOMETRY OF SURFACE COPPER(II) COMPLEXES

Synthetic supports and coper(II) complexes anchored on themby an incipient wetness impregnation with subsequent drying at 100 °C have been characterized by IR and UV-vis diffuse reflectance spectroscopy. As can be seen, the synthetic zeolites demonstrate IR bands corresponding to both water molecule vibrations (stretching and deformation) and stretching vibrations of the crystal framework. The 6 main absorption bands in the IR spectrum of SiO2are characteristic of stretching and deformation vibrations of OH groups, water molecules, and the bonds in Si–O–Si, Si–O, and Si–OН fragments. Absorption bands in the IR spectrum of Al2O3correspond to stretching vibrations of OH groups bound to aluminum being in its tetrahedral (AlIV) and octahedral (AlVI) configurations. As appears from the UV-vis diffuse re-flectance spectra, on all supports under study, i.e. synthetic zeolites (NaX, NaA, KA), alumo-gel, and silica gel (KSMG grade), copper(II) is situated in the mixed-ligand (H2O, Cl-) octa-hedral surroundings. A wavelength corresponding to d-d transition in the Cu(II) ion anchored to the supports under study decreases in the order CuCl2/SiO2(KSMG) (820 nm) >CuCl2/NaA (733 nm) >CuCl2/Al2O3 (720 nm) ≈CuCl2/NaХ (716 nm) >CuCl2/KA (690 nm). Thus, in addi-tion to the geometry of the surface copper(II) complexes, it has been found that the role of the support is in the short-wave shifting of the band corresponding to d-d transition in the Cu(II) ion showing a distortion in the octahedral symmetry of Cu(II) environment.

INVESTIGATION OF CLINOPTILOLITE MODIFIED WITH IONS OF HYDROGEN, PALLADIUM(II), AND COPPER(II) BY IR AND DIFFUSE REFLECTANCE SPECTRAL METHODS

Changes appeared in IR and diffuse reflectance UV-vis spectra of clinoptilolite as a result of its modification by boiling in nitric acid solutions (0.25-3 M) and anchoring active components on it were analyzed. As was shown by IR spectroscopy, the increase in acid concentration caused a high-frequency shift of the band attributed to asymmetric stretching vibrations of the Si-O-Al fragment due to the clinoptilolite dealumination. The values of this shift were not changed after active components anchoring on the acid modified clinoptilolite samples. The band of deformation vibrations of OH groups in water molecules (at 1633 cm-1 for natural clinoptilolite) was weakly affected (a slight high-frequency shift) by the acid concentration increase and remained practically unaffected by anchoring palladium and copper ions. However, the effect of Pd(II) and Cu(II) anchoring on IR spectra could be observed through a low-frequency shift of the band characterizing stretching vibration νОН of OH groups in water molecules indicating some disturbance of hydrogen bonds in H2O molecules and a change in their energy. The UV region of diffuse reflectance UV-vis spectra of all anchored catalyst samples showed the appearance of new intense bands at 224-226, 279-284, and 327-334 nm which were absent Pd-Cu complexes which attendance is necessary for catalytic low-temperature oxidation of carbon monoxide with air oxygen. It should be noted that a new band appeared at 351-363 nm would be assigned to individual Pd(II) indicating that some portion of palladium(II) ions did not participate in the formation of the catalytically active bimetallic Pd-Cu complexes. The presence of individual palladium(II) was confirmed by the fact that only the bends characteristic of square planar palladium(II) complexes were observed in the palladium(II) absorbing region in the visible part of diffuse reflectance UV-vis spectra. Additionaly, theses spectra also contained the bends corresponding to d-d transition in the bimetallic palladium-copper complexes. As well, a low-intensity band centered at 740-750 nm could be assigned to copper situated in the bimetallic Pd-Cu complexes because the band was shifted towards the lowfrequency region as compared with the mononuclear octahedral aqua complex of copper(II). Judging from these diffuse reflectance UV-vis spectral data and the results obtained in our previous works, the optimal conditions for formation of the clinoptilolite anchored Pd-Cu complexes were achieved when clinoptilolite was boiled in 3 M HNO3 for 30 min complexes were achieved when clinoptilolite was boiled in 3 M HNO3 for 30 min.

In-situ measurements of fluorine and chlorine speciation and partitioning between melts and aqueous fluids in the Na2O-Al2O3-SiO2-H2O system

The effect of pressure and temperature on the structure of silicate melts coexisting with silicasaturated aqueous electrolyte fluids enriched in fluorine or chlorine in the Na 2 O-Al 2 O 3 -SiO 2 -H 2 O system has been described. In situ measurements were conducted with the samples at desired temperatures and pressures in a hydrothermal diamond-anvil cell (HDAC) by using microRaman and FTIR spectroscopy techniques. The data were acquired at temperatures and pressures up to 800 °C and 1264 MPa, respectively. In silicate melts, the intensity of the infrared bands assigned to the stretch vibration of OH-groups is smaller than those of coexisting molecular H 2 O when F and Cl are present in the melt structure. This difference reflects the interaction of F or Cl with H 2 O in the melts. With decreasing pressure and temperature (P-T) conditions, SiF complexes are favored in the melt over that in coexisting fluid, perhaps because of decreasing silicate concentration in fluids with decreasing temperature and pressure. In these melts, the solubility of Cl, likely in the form of NaCl, increases with decreasing P-T conditions, whereas the abundance of such complexes in coexisting fluids decreases in favor of HCl. Our experimental data were employed to model the ascent of a fluid-saturated magma from the upper mantle to the shallow crust. This modeling offers insights into F and Cl partitioning between and the speciation of F and Cl in melts and magmatic fluids. We suggest that the formation of stable SiF and NaCl complexes and their increasing solubilities in silicate melts during magma ascent may explain the late volcanic degassing of F and Cl compared with the degassing behavior of other volatile species.

Effect of alkali halide salt additives on the structure of poly(vinyl alcohol) films cast from aqueous solutions

The molecular structures of poly(vinyl alcohol) films cast from polymer aqueous solutions (1 mol/L) containing 0.1 mol/L of LiCl, NaF, NaCl, KCl, CsCl, KBr, and KI salts are studied via FTIR spectroscopy. The addition of any of these salts except LiCl leads to an increase in the degree of crystallinity of poly(vinyl alcohol) in a film by a factor of 1.3–1.6. In contrast, LiCl significantly decreases the crystallinity of the polymer. It is found that, in the IR spectra of the films containing salt additives, the position of the maximum in the band of the stretching vibrations of OH groups of the polymer is shifted relative to its position in the IR spectra of the films free of salt additives. The magnitude and direction of this band shift depend on the types (anion or cation) and radii of ions comprising salts. The observed effects are interpreted in terms of existing ideas on the interactions of salt ions with the OH groups of water and other hydroxyl-containing molecules.

Structural and luminescence studies on Er3+/Yb3+ co-doped boro-tellurite glasses

The present work reports structural and optical behaviour of the Er3+/Yb3+ co-doped boro-tellurite glasses 50TeO2+15H3BO3+(5−x−y)La2O3+15MgCO3+15SrCO3+xEr2O3+yYb2O3 (where x=1, y=0, 0.5, 1 and 2 in wt%) studied through Fourier transform infrared (FTIR), Raman, absorption, luminescence, upconversion luminescence and lifetime measurements for green laser applications. The TeOTe, O3BOBO3 bond bending vibrations and the fundamental stretching vibration of OH groups are confirmed through FTIR and Raman spectra. Through the absorption spectra, bonding parameters, oscillator strengths and Judd–Ofelt (JO) parameters were calculated and reported. From the luminescence spectra, radiative parameters have been calculated for the 2H9/2→4I15/2,4S3/2→4I15/2 and 4I13/2→4I15/2 excited state transitions. Upconversion luminescence spectra of the prepared glasses have been recorded and the excited state absorption (ESA) and Energy transfer (ET) processes are discussed. The luminescence decay curves for the 4I13/2→4I15/2 transition of the title glasses under 980 excitation wavelength have also been studied and reported.

Synthesis of 2,6-diaryl-3-benzoyl-4-hydroxy-4-phenyl-1,1-cyclohexanedinitriles

We found that the reaction of chalcones Ia, Ib with malononitrile in the presence of KOH in ethanol solution at room temperature gave rise to 2,6-diaryl-3-benzoyl4-hydroxy-4-phenyl-1,1-cyclohexanedinitriles IIa, IIb. In the fi rst stage apparently the malononitrile adds to the double bond of the chalcone to form the intermediate compound A that along the mechanism suggested for the cycloketols formation [1] undergoes the cyclization into cyclohexanedinitriles IIa, IIb. Compounds IIa, IIb are crystalline substances soluble in DMSO, DMF, ethanol, butanol, acetonitrile, and insoluble in water. Their IR spectra contain absorption bands of the stretching vibrations of OH group in the region 3408–3445 cm–1, of carbonyl group in the region 1644–1650 cm –1, and also of cyano groups in the region 2350–2360 cm –1. In the 1H NMR spectra of compounds IIa, IIb alongside the signals of the aromatic protons signals appear of the CH2 group in the position 5 as two doublets of doublets at 2.05–2.16 and 4.35–4.65 ppm, of the proton of the CH group in the position 6 of the ring as a triplet at 3.14–3.26 ppm, of protons from two CH groups in the positions 2 and 3 of the alicycle as two doublets with the centers at 4.67–4.92 and 4.59– 4.83 ppm, and a singlet of the hydroxy group proton at 5.72–5.82 ppm. Mass spectrum of compound IIa contains peaks of fragment ions, m/z: 253 [C6H5COCHCHC6H5NO2], 224 [C6H5COCH2COC6H5], 105 [C6H5CO], 77 [C6H5] that confi rm the assumed structure The fragmentation of compound IIb is of similar character. 3-Benzoyl-4-hydroxy-2,6-di(3-nitrophenyl)-4-phenylcyclohexane-1,1-dicarbonitrile (IIa). To a mixture of 0.005 mol of 3-nitrobenzalacetophenone and 0.005 mol of malononitrile was added 30 ml of 0.1% ethanol solution of KOH, the mixture was heated to dissolution and left standing for 24 h at room temperature. The separated precipitate was fi ltered off, washed with water, and recrystallized. Yield 0.66 g (23%), mp 166–168°C (acetonitrile). IR spectrum, ν, cm–1: 3408 (OH), 2350 (CN), 1644 (C=O). 1H NMR spectrum, δ, ppm: 2.16 d.d (1H, C5HAHC, J 2.7, 13.9 Hz ), 3.26 t (1H, C6H, J 13.9 Hz), 4.65 d.d (1H,C5HAHC, J 2.7, 13.9 Hz ), 4.83 d (1H, C2H, Ph N N

Theoretical infrared spectrum of OH-defects in forsterite

The infrared spectroscopic properties of selected defects in forsterite are investigated by first-principles calculations, starting from previously proposed OH-incorporation mechanisms. The considered defects include the fully protonated M1 vacancy, fully protonated Si vacancy (hydrogarnet defect), and protonated Si vacancy associated with Ti incorporation at the M1 site (''titanoclinohumite'' defect). Our findings establish that the previously proposed models for Mg and Ti defects are consistent with the observed infrared spectra. In contrast, a new model of Si defect is proposed, based on relative energies, vibrational frequencies, polarization properties and absorption coefficients. The theoretical results emphasize the critical role of the coupled vibration of OH groups in the relative intensities of OH stretching absorption bands. In contrast integrated absorption coefficients are less affected by coupling. The observed theoretical relation between the integrated absorption coefficient of OH defects and vibrational frequencies is consistent with recent experimental data.

Infrared spectra and pharmacological activity of hindered phenols

IR Fourier spectra of pharmacologically active sterically hindered phenols in CCl4 solutions are studied. A relationship between the absorption intensity in the spectral range of the free vibrations of OH-groups and the antimicrobial activity of the phenols is discovered. If the hydroxyl groups are in an ortho-position within a molecule, then intramolecular hydrogen bonds are formed. The hindered phenols with nonassociated hydroxyl groups are the most pharmacologically active.

IR spectra in the studies of anion sorption on natural sorbents

This work presents the results of FT-IR spectroscopic studies of anions – chromates, phosphates, arsenates, sulfates and nitrates – sorbed from aqueous solutions (different concentrations of anions) on natural sorbents. The sorption has been conducted on zeolite (clinoptilolite) and smectite (mixtures of clay minerals containing mainly montmorillonite and kaolinite) which have been separated from natural Polish deposit. The Na-forms of sorbents were exchanged with hexadecyltrimethylammonium cations (HDTMA +). Cation exchange capacities (CEC) of clinoptilolite and smectite were measured. Their values are 23 mmol/100 g and 41 mmol/100 g respectively. The used initial inputs of HDTMA correspond to 100% (1.0) and 200% (2.0) CEC of the minerals. Organo-modified sorbents were subsequently used to immobilization mentioned anions. It was proven that those anions’ sorption causes changes in IR spectra of the HDTMA-zeolite and smectite. These alterations are dependent on the kind of anions that were sorbed. In both cases, variations are due to bands corresponding to the characteristic Si–O(Si,Al) vibrations (occurring in alumino- and silicooxygen tetrahedra building spatial framework of zeolite or layer structure of smectite), OH group vibrations and alkylammonium surfactant vibrations have been observed. Systematic changes in the spectra connected with the anion concentration in the initial solution have been revealed. The amounts of sorbed CrO 4 2 - , AsO 4 3 - , PO 4 3 - , SO 4 2 - , and NO 3 - ions were calculated from the difference between their concentrations in solutions before (initial concentration) and after (equilibrium concentration) sorption experiments. Concentrations of chromates were determined by colorimetry using the biphenylocarbazide method. For phosphates and arsenates molybdenum blue method, turbidimetric method for sulfates and hydrazine reduction method for nitrates was used.

Isomorphous substitution of samarium and gadolinium for calcium in hydroxyapatite structure

Isomorphous substitution of samarium and gadolinium for calcium in synthetic hydroxyapatite by the scheme Ca2+ + OH− → Ln3+ + O2− was studied by X-ray powder diffraction and IR spectroscopy. The homogeneity region of Ca10 − xLnx(PO4)6(OH)2 − xOx phases of variable compositions synthesized at 1100°C was found to exist up to x of 1.8 for Sm and 1.4 for Gd. In the heterogeneous region of solid solutions, phases with Ln3PO7 and LnPO4 structures were formed. The structures of some solid solutions were refined by the Rietveld method, which allowed us to establish that the substitution of Ln3+ ions for Ca(2) positions is preferred. Changes in the intensities of the absorption bands of stretching and libration vibrations of OH groups are indicative of a partial dehydration of oxyhydroxyapatite. The substitution was shown to decrease Ca(2)-O(OH) and P-O distances and increase Ca(2)-O(1,2,3) distances.

Vibrations of the OHO hydrogen bond in t-butanol

Experimental INS (Inelastic Neutron Scattering) spectrum of t-butanol was compared with theoretical spectra of t-butanol monomer and OHO hydrogen bonded dimer calculated at B3LYP/6-31++G∗∗ level. Formation of the OHO hydrogen bond was reflected in shifting of the bands of the stretching and bending vibrations of OH group as well as arising of the bridge vibrations in the low frequency range. INS spectroscopy appeared to be an important tool to investigate the low frequency range of the vibrational spectrum where out-of-plane OH deformation bands and hydrogen bridge stretching and bending bands are located.

Infrared and Raman studies of manganese dihydrogen phosphate dihydrate, Mn(H 2PO 4) 2·2H 2O. Part II: Region of the internal OH group vibrations

Infrared and Raman spectra of Mn(H 2PO 4) 2·2H 2O and of series of deuterated analogues recorded at room temperature (RT) and at the boiling temperature of liquid nitrogen (LNT) have been presented and analyzed with respect to the OH vibrations. In the OH stretching mode region ABC bands behaviour is observed in accordance with the structural data for presence of a short hydrogen bond (2.609 Å). It is presumed that the A band of the ABC trio most probably originates from the stretching OH vibrations of strongly hydrogen bonded POH(1) group, but the contribution of the second POH(2) group and the water molecule should be also considered. The strength of the four hydrogen bonds as deduced from the infrared wavenumbers of the isotopically isolated OD groups has been discussed in terms of the respective O···O distances, the hydrogen bond acceptor capability of the oxygen atoms, the hydrogen bond donor strength of the H 2PO 4 ions and water molecules and the hydrogen bond acceptor angles. The influence of the cooperative effect has been also analyzed.

Substitutions of neodymium for strontium in the Sr5(VO4)3OH structure

Neodymium-for-strontium isomorphic substitutions in synthetic hydroxovanadate Sr5 − xNdx(VO4)3(OH)1 − xOx were studied from 600 to 800°C using powder and single-crystal X-ray diffraction (the Rietveld technique) and IR spectroscopy. Single-phase solid solutions at 800°C are formed in the range up to x = 0.14. At higher x, a Sr3(VO4)2 phase exists along with the apatite solid solution. In the range of 0 < x ≤ 0.14, the intensity of the IR bands due to the stretching and libration vibrations of OH groups decreases with increasing x. Single-crystal X-ray diffraction shows that neodymium mostly substitutes for strontium atoms at the Sr(1) sites in the solid solution with x = 0.14.

The application of FTIR spectroscopy on characterization of paper samples, modified by Bookkeeper process

Paper and other lignocellulosic materials undergo the destruction as a result of ageing, influenced by various factors and accelerated by the formation of acids from components, used during its production [S. Katuščák, Wood Res. 45 (2000) 1; S. Katuščák, L. Ďurišová, Wood Res. 118 (1988) 75]. Various deacidification processes were developed in an order to prevent or eliminate acidic destruction. Bookkeeper, based on MgO dispersion in perfluoroheptane, is the widely used one [J. Hanus, J. Rychlý, J. Mináriková, L. Matisová-Rychlá, S. Katuščák, M. Vrška, V. Bukovský, in: J. Kollar, M. Strlic, J.B.G.A. Havermans (Eds.), Proceedings of the International Conference on Durability of Paper and Writing, Ljubljana (Slovenia), November 16–19, 2004, p. 22]. In present work, the effect of its application is studied by means of FTIR DRIFT technique in an order to fill up the lack and the certain contradiction of information about its action on real paper samples. The spectral changes in Bookkeeper modified samples comparing to reference (unmodified sample), along with the influence of various ageing conditions (temperature 23.3, 35 and 80 °C at relative humidity 81 and 98%) were investigated. The application of Bookkeeper reagent causes significant changes mostly in the region of 3700 cm −1, assigned to the coordination of stretching vibrations of OH groups coordinated with Mg 2+ ions; 3000/1600 cm −1—valence vibrations of OH groups of water and hydrogen bond structures; in the region 1740–1720 and 1630–1650 cm −1 indicating the changes in carbonyl/carboxylate content, which also influences the relative humidity and the rise of temperature, accelerating the transformation of carbonyls to carboxylates.

Intramolecular hydrogen bonding and structure of stereoisomeric 20(22)-hydroxy-22(23)-isoxazolinyl steroids

We have used IR spectroscopy and the quantum chemical AM1 method to study stereoisomeric 22(23)-isoxazolinyl steroids with a hydroxyl group at C20 or C22, in order to establish the spectral features that will allow us to identify their stereoisomers. We have carried out a conformational analysis of isoxazolinyl steroid stereoisomers, and we have calculated the populations of their stable conformers. We have assigned the bands in the IR spectra of the stereoisomers in the region of the stretching vibrations of OH groups, and have analyzed the possibility of intramolecular hydrogen bond formation between the OH groups and proton-acceptor centers of the isoxazoline ring.

Behaviour of Li + and Cu 2+ in heated montmorillonite: Evidence from far-, mid-, and near-IR regions

Infrared spectroscopy in the far (FIR), mid (MIR), and near (NIR) regions was used to study the structural changes of a thermally treated clay mineral montmorillonite saturated with Li + or Cu 2+ cations (Li-JP and Cu-JP samples). Cation exchange capacity (CEC) values decreased by 89 and 64% in Li- and Cu-samples, respectively, heated at 300 °C. The IR spectra confirm that the charge of exchangeable cations significantly affect their final position after fixation upon heating. No absorption bands related to the vibrations of interlayer cations were observed in the FIR spectra of unheated or heated samples; however, different modification of the complex vibrational mode involving motion of octahedral aluminium relative to the tetrahedral sheet was observed near 197 cm −1. The vibrations of OH groups in both MIR ( ν OH, 3630–3670 cm −1) and NIR (2 ν OH, 7070–7170 cm −1) regions proved that the Li + migrated into the octahedral vacancies, thus creating local trioctahedral domains, such as AlMgLiOH. Though Cu 2+ has similar ionic radius as Li +, no spectral features indicating its presence in the octahedral positions have been found even in the sample heated at 300 °C. Fixed Cu(II) is supposed to be located deep in the ditrigonal cavities of the tetrahedral sheets of Cu-JP. The NIR spectra of heated Cu-JP samples show new components near 7045 and 5170 cm −1. These modes are believed to correspond to overtone bands associated with hydrated Cu 2+ ions tightly bound in close proximity to the ditrigonal cavities of the basal surface (O basal Cu 2+ H 2O). The NIR spectra confirm that in Cu-JP heated at 200 °C, then saturated with Li + and Cu 2+ and heated again at 300 °C small Li + ions migrate into the vacant octahedral sites even though Cu(II) have been trapped in the hexagonal cavities of the tetrahedral sheets in the course of previous heat treatment.

IR Spectroscopic Investigation and Conformational Analysis of Unsaturated C20 and C22 Steroid Alcohols

With the IR-spectroscopy method and the quantum-chemical AM1 method, the Δ22 and Δ23 steroids containing a hydroxyl group at C20 or C22 have been studied in order to elucidate the mutual arrangement in space of the hydroxyl group and of the double bond in the side chain of the molecules. The conformational analysis of steroid alcohols has been performed and the population of their stable conformers has been calculated. The frequencies of the bands in the IR spectra of alcohols in the region of the stretching vibration of OH groups have been assigned to certain conformers and the possibility of formation of the intramolecular hydrogen bond of the OH groups with the π-electron cloud of C=C bonds has been analyzed.