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Structural Elucidation, Optical and Magnetic Properties of Tetraphenylborate Salt of 2,5-[1-Methyl-4-[2-(4-hydroxyphenyl)ethenyl)]pyridinium]-butane

Stoyanov S., Koleva B. B., Kolev T., Petkov I., Spiteller M.

Polish Journal of Chemistry

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2008

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Vol. 82, nr 11

2167-2178

EN

Structure, magnetic and optical properties of tetraphenylborate salt of 2,5-[1-methyl-4-[2-(4-hydroxyphenyl)ethenyl)]pyridinium]-hexane were performed for condensed phase by means of solution and solid-state conventional and linear-polarized IR-spectroscopy of oriented colloids in nematic host, UV-Vis and fluorescence methods, HPLC MS-MS tandem and ESI mass spectrometry, 1H-, 13C- and 1H-1H COSY NMR, TGV and DSC methods. Electronic structure and vibrational analysis were carried out by quantum chemical calculations at two levels of theory second-order Moller-Plesset perturbation theory (MP2) and density functional theory (DFT) using 6-31G* basis set. B3LYP method, which combines Becke's three-parameter non-local exchange functional with the correlation function of Lee, Yang and Parr, was applied.

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Hydrogen, carbon and oxygen isotopes in pine and oak tree rings from Southern Poland as climatic indicators in years 1900 - 2003

Szczepanek M., Pazdur A., Pawełczyk S., Böttger T., Haupt M., Hałas S., Bednarz Z., Krąpiec M., Szychowska-Krąpiec E.

Geochronometria

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2006

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Vol. 25

67-76

EN

Carbon, oxygen and hydrogen stable isotopes in tree rings are sensitive indicators of climate changes. We have measured carbon, oxygen and hydrogen isotope ratios in ?-cellulose extracted from annual rings of pine (Pinus sylvestris L.) and oak (Quercus robur L.) growing in the Niepołomice Forest, Southern Poland. The presented isotope records cover the period 1900-2003. In this paper we compare the values of δ13C, δ18O and δ2H observed in the wholewood of pine and in the latewood of oak with meteorological data (temperature, precipitation and sunshine). The highest significant values of correlation coefficients calculated between δ13C and the meteorological data are: -0.26 for temperature, 0.25 for precipitation and 0.41 for sunshine. On the basis of our investigations we deduced that pine is a more sensitive indicator of environmental changes than oak. Our investigation proves that the best indicators are: hydrogen for summer temperature and oxygen for summer precipitation. We noticed a rapid decrease of pine δ13C values in 1966 from -22.46‰ to -24.64‰.

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Creatinine and Creatininium Cation in Water Solution. Tautomerism and Quantitative Interpretation of the Solution Acidity Effect on 1H, 13C and 14 N NMR Chemical Shifts

Kotsyubynskyy D., Molchanov S., Gryff-Keller A.

Polish Journal of Chemistry

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2004

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Vol. 78 / nr 2

239-248

EN

1H, 13C and 14N NMR chemical shifts for creatinine in water solutions of various acidity have been measured. Analysis of these data enabled determination of the acidity constant of creatininium cation and the chemical shifts of the neutral and protonated forms of creatinine. Molecular energies and carbon and nitrogen magnetic shielding constants for various tautomeric structures of the investigated species have been calculated using the quantum chemistry method GIAO DFT B3LYP/6-311++G(2d,p). Compilation of the available experimental and theoretical results has provided additional information on the problem of tautomerism of this important biological molecule.

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Influence of Intermolecular Interactions on Nuclear Magnetic Shielding Constans of OCS

Jackowski K., Les A., Makulski W., Wozniak K.

Polish Journal of Chemistry

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2002

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Vol. 76 / nr 4

575-580

EN

The gauge-included atomic orbital (GIAO) method has been applied within the coupled Hartree-Fock (CHF) approximation to compute 13C, 17Oand 33SNMRchemical shifts for solid OCS. Increasing clusters of OCS molecules taken out of crystal lattice have been used in an additive approximation to estimate the effect of intermolecular interactions on shielding of the carbon, oxygen and sulphur nuclei. There is a very good agreement achieved for NMR chemical shifts between the results of calculations and experimental measurements obtained for 13C and also some discrepancies for 17Oand 33S nuclei, probably due to deficiency of ab-initio calculations (lack of electron correlation). The results reveal that the 33S NMR signal of OCS is strongly dependent on intermolecular interactions.

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FT-IR and NMR stedies of proton sponge character of Cis-1,2-bis(diethylaminomethyl)cyclohexane

Brzezinski B., Grech E., Klimkiewicz J., Schroeder G., Stefaniak L., Urjasz H.

Polish Journal of Chemistry

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1998

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Vol. 72, nr 2

284-291

EN

Cis-1,2-bis(diethylaminomethyl)cyclohexane (DEAMCH) was synthesized and its pK-a values in acetonitrile were measured. Dual behevioral of DEAMCH was observed in the reaction with various acids: HClO4, 4-tert-butylphenol, 4-cyanophenol and pentachlorophenol (PCP) in acetonitrile and acetone-d-6 solutions, respectively, when studied by FT-IR as well as (1)H, (13)C and (15)N NMR spectroscopy. An intramolecular NHN(+) hydrogen bond was found in 1:1 complex of DEAMCH with HClO4 in solution. This hydrogen bond was, however, weaker than those previously observed in other protonated proton sponges. In complexes of DEAMCH with 4-cyanophenol both NHN(+) intramolecular hydrogen bond and structurally symmetrical intermolecular homoconjugated (OHO)(-) hydrogen bonds were formed. These properties of DEAMCH demonstrate its proton sponge like character. On the other hand, in complexes of DEAMCH with more acidic phenol such as PCP intermolecular hydrogen-bonded complexes are formed, in which the OH protons are localized at the amino groups. For these O(-)...HN(+) hydrogen bonds a strongly asymmetrical double minimum proton potential with the well at the N atom is present, characteristic of complexes having no proton sponge like character.