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O 7 were measured. The temperature dependence of phonons was studied in the range 4-295 K. The discussion of the results is based on the factor group approach for the tetragonal P42 1 m (D 3 2d ) space group with Z = 2. The discussion of the internal vibrations of the Ge 2 O 7 unit and external modes is made on the basis of the literature data and phonon calculations. The results obtained for the spontaneous Raman scattering were used in the discussion of the stimulated Raman spectra of the studied materials.

Articles you may be interested inCopper doping of ZnO crystals by transmutation of 64Zn to 65Cu: An electron paramagnetic resonance and gamma spectroscopy study The X-band electron paramagnetic resonance spectra of Cu+ + ions doped into amorphous, tetragonal, and hexagonal Ge02 have been observed at 295°K. Optical absorption and reflection data for, respectively, the doped glass and polycrystaIIine samples were also obtained. From the experimental results, the symmetry of the cupric complexes and some characteristics of the metal ion's bonding are deduced. In amorphous and tetragonal Ge02, the Cu+ + ions are basically in sixfold coordination. Because these cupric complexes exhibit a significant axial distortion (elongation), however, they have been treated as having square planar symmetry. Since the host cations in amorphous Ge02 are tetrahedrally coordinated, the presence of square planar Cu+ + complexes suggests that, to a significant extent, the cupric ions determine their immediate environment in the glassy host. The Cu+ + ions in hexagonal Ge02 appear to be located within the system of oxygen channels (tunnels) which are present in this crystal.1. SIEGEL AND J. A. LORENC

Thirteen edible oils: sunflower, avocado, hemp, high-linolenic flax, low-linolenic flax, safflower, walnut, roasted sesame, rice, corn, rapeseed, pumpkin seed, and hazel were studied in this work. Their fatty acid composition, iodine, acidic, peroxide, and saponification values were determined. Infrared and Raman spectra of the oils were recorded in the range 400-3200 cm −1 . The integral intensities of the bands at about 1655 and 2852 cm −1 corresponding to ν(C=C) and ν(CH 2 ) vibrations were evaluated and used to construct a relationship between the spectroscopic data and the iodine value. The following linear dependencies were obtained: I ν(C=C) /I ν(CH2) = 7.449 × 10 −4 × iodine value -0.0339 and I ν(C=C) /I ν(CH2) = 9.299 × 10 −4 × iodine value -0.023 for the infrared and Raman spectra with a correlation coefficient 0.988 and 0.976, respectively. These calibration lines can be used to determine the iodine value for oils with unknown unsaturation level, and may be applied for margarines and other fatty materials.

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Molecular structure, vibrational energy levels and potential energy distribution of 1H-imidazo[4,5-b]pyridine, 3H-imidazo[4,5-b]pyridine, 5-methyl-1H-imidazo[4,5-b]pyridine, 6-methyl-1H-imidazo[4,5-b]pyridine and 7-methyl-3H-imidazo[4,5-b]pyridine were determined using density functional theory (DFT) at the B3LYP/6-31G(d,p) level. The optimised bond lengths and bond angles are in good agreement with the X-ray data of 5-methyl-1H-imidazo[4,5-b]pyridine obtained in the present work (Pbca space group; a = 8.660.2/, b = 11.078.2/, c = 11.078.3/Å, Z = 8). The N + H group plays the role of a proton donor in a medium strong hydrogen bond of the type N-H· · ·N, linking the N-atom of the pyridine with the adjacent molecule related by the symmetry operation: 1/2 − x, y − 1/2, z(N· · ·N = 2.869.25/Å). The presence of hydrogen bond is confirmed by appearance in the IR spectra of a very broad and strong contour in the 2000-3100 cm −1 range. The place of substitution of the methyl group at the pyridine ring influences the proton position of the NH group at the imidazole unit.

The copper phytate IP6Cu, IP6Cu 2 and IP6Cu 3 complexes were synthesized changing the phytate to metal mole ratio. The obtained products have been characterized by means of chemical and spectroscopic studies. Spectroscopic ATR/IR, FT-Raman, UV–Vis, EPR and magnetic measurements were carried out. The structures of these compounds have been proposed on the basis of the group theory and geometry optimization taking into account the shape and number of the bands corresponding to the stretching and bending vibrations of the phosphate group and metal–oxygen polyhedron. The role of the inter- and intra-hydrogen bonds in stabilization of the structure has been discussed. EPR studies showed that a local rhombic symmetry of copper ions appears in the studied phytates. Dominant interactions show antiferromagnetic properties depending on the content of paramagnetic ions. Electronic supplementary material The online version of this article (10.1007/s00775-018-1622-0) contains supplementary material, which is available to authorized users.

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