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1

Adenine and Some of Its Analogues in DMSO-d6 Solution: an NMR and GIAO-DFT Study

Dybiec K., Molchanov S., Gryff-Keller A.

Polish Journal of Chemistry

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2009

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Vol. 83, nr 5

857-868

EN

The results of GIAO-DFT calculations [at B3LYP/6-311++G(2d,p) PCM and PBE1PBE/6-311+G(2fd,p) PCM levels] of 13C NMR and 15N NMR parameters have been employed to reinvestigate tautomerism of adenine in DMSO solution. The separate 13C NMR sig nals of N7-H and N9-H adenine tautomers have been observed for the first time. The ex erimental 13C chemical shifts, 3J(C,H) coupling constants and 15N chemical shifts of adenine and three of its methyl derivatives (9MeA, 7MeA and 3MeA) have been quantitatively analyzed using the calculated parameter values. This procedure has provided the solution populations of the predominant adenine tautomers being in agreement with the available literature data. The apparent dependence between the amino group geometry and the chemical shift of the adjacent carbon in 2-aminopyridine system has also been discussed.

2

King Is Naked: Comparison of ab initio and DFT Calculations of Magnetic Shielding of 13C Nuclei in Chloromethanes

Molchanov S., Gryff-Keller A.

Polish Journal of Chemistry

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2007

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Vol. 81, nr 1

137-140

3

1H NMR, 13C NMR and Computational Study of the Structure of Salicylaldehyde Anion in Solution

Horbaczewski M., Szczeciński P., Gryff-Keller A., Molchanov S.

Polish Journal of Chemistry

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2007

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Vol. 81, nr 12

2089-2096

EN

1H NMR and 13C NMR spectra of salicylaldehyde potassium salt in DMF-d7 solution with addition of kryptofix 222 were mea sured. Quantitative comparison of car bon chemical shifts with shielding constants calculated for syn and anti con form ers of salicyl aldehyde an ion [GIAO DFT B3LYP/6-311G(2d,p) PCM] re vealed that in the applied conditions the anti form prevailed. Similar correla tion performed for salicylaldehyde lith ium salt indicated that in this case the syn conformer dominated. Analysis of experimental and calculated J(1H,13C) and J(1H,1H) values supported above conclusions.

4

1H NMR, 13C NMR and Computational DFT Study of the Structure of 2-Acylcycloalkane-1,3-diones in Solution

Szczeciński P., Gryff-Keller A., Molchanov S.

Polish Journal of Chemistry

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2007

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Vol. 81, nr 8

1449-1455

EN

1H and13C NMR spectra of 2-acylcyclopentane-1,3-dione [acyl = formyl (1); acetyl (2)] and 2,6-dioxocyclohexanecarboxylic acid (3) have beenmeasured. The optimummolecular structures of endo- and exo-enolic forms of investigated objects in solution have been found using DFT method with B3LYP functional and 6-311G(2d,p) basis set. The theoretical values of the NMR parameters have been then calculated using GIAO-DFT method with the same functional and basis set. The theoretical data obtained for compounds 1–3 have been used to interpret their experimental NMR spectra in terms of the equilibrium between different tautomers. It has been found that for investigated triketones an endo-tautomer overwhelmingly prevails.

5

Spectroscopic 1H NMR, 13C NMR and Theoretical DFT Study of Isoguanine and 8-Oxoadenine in Water and DMSO-d6 Solutions

Dybiec K., Gryff-Keller A.

Polish Journal of Chemistry

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2006

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Vol. 80, nr 11

1831-1843

EN

1Hand 13CNMRspectra of isoguanine (2-hydroxyadenine) and 8-oxoadenine inH2Oand DMSO-d6 solutions of various acidity have been interpreted using arguments based on the results of several 1D and 2D NMR experiments and theoretical DFT-based calculations. The collected data for H2O solutions can serve for identification of these compounds in body fluids during medical analysis. The 1H and 13C NMR spectra of the investigated compounds in DMSO-d6 solutions have provided information on their tautomeric forms and the mobility of their exchangeable protons.

6

Main Factors Governing Chemical Shifts of Carbon and Nitrogen in Cyano Group. An Experimental and Theoretical Study

Molchanov S., Gryff-Keller A.

Polish Journal of Chemistry

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2006

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Vol. 80, nr 7

1031-1038

EN

The feasibility of a description of magnetic shielding of carbon and nitrogen nuclei of cyano group in various cyano compounds as a net result of the interplay of different structural factors is discussed. Analysis of experimental data and DFT GIAO calculations of shielding constants have shown that the main factors governing the carbon chemical shifts are the heavy-atom and inductive effects, although the resonance and steric properties of a substituent are also of some importance. On the other hand, the shielding of the cyano nitrogen is connected mainly with the redistribution of _-electrons within the cyano group, which is the result of mesomeric interaction, and, to a lesser extent, with the inductive properties of the substituent. The steric and heavy-atom effects of the substituent seem to be irrelevant for the shielding of cyano nitrogen.

7

Determination of the Absolute Configuration of 2-Hydroxyglutaric Acid, 5-Oxoproline and Vigabatrin in Urine by Chiral Derivatization and 13C or 19F NMR

Bal D., Gryff-Keller A.

Polish Journal of Chemistry

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2006

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Vol. 80, nr 7

1021-1030

EN

Procedures for enantiomeric recognition of 2-hydroxyglutaric acid and 5-oxoproline - markers ofmetabolic diseases, and of vigabatrin - an antiepileptic drug, suitable for urine samples, have been elaborated. They rely upon derivatization of the metabolites with a chiral reagent; this is made without separation of these compounds from a biological sample. The diastereotopic metabolite derivatives are then distinguished using 13C or 19F NMR spectroscopy. This procedure is not so simple as one proposed previously, but, as opposite to the latter method, it seems to be unfailing and still not too complicated.

8

Rozróżnianie molekuł a spektroskopia NMR cieczy

Gryff-Keller A.

Wiadomości Chemiczne

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2005

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[Z] 59, 1-2

67--91

EN

The high resolution NMR spectroscopy in liquids is a convenient tool for differentiating stereoisomers. Diastereomeric structures having different spatial distribution of electron density produce different magnetic environments for their nuclei and in consequence have, in general, different NMR spectra. The same concerns diastereotopic groups in a molecule. On the other hand, enantiomers or enantiotopic groups can be differentiated only when they are placed in a chiral environment. It can be accomplished by transforming enantiomers into their diastereomeric derivatives with the aid of chiral derivatising reagents, or by using chiral complexing or solvating agents. The most popular methods of practical realization of these approaches have been reviewed and illustrated with some examples. The spectroscopic differentiation of enantiomers provides a possibility of determining their absolute configurations.

9

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.

10

Wpływ częściowego uporządkowania orientacji cząsteczek na ich widma NMR dużej zdolności rozdzielczej

Ejchart A., Gryff-Keller A.

Wiadomości Chemiczne

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2000

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[Z] 54, 11-12

949-969

EN

Molecules of solute in the liquid phase can display partial orientation owing to the interaction of an anisotropic magnetic susceptibility tensor with an external magnetic field or/and to the interaction with anisotropic liquid crystal solvent. In the latter case orientation of the solvent molecules is caused by the magnetic field as well. Formal, statistic description of the solute molecular orientation is identical in both cases and it has been demonstrated without recalling to the Wigner rotation matrices. Since the orientation of solute molecules is not averaged out due to the rotational diffusion completely, several interactions, additional to the isotropic liquid phase, manifest in the NMR spectra, namely, dipolar nad quadrupolar interactions as well as anisotropic parts of chemical shifts (screening) and spin-spin couplings. Therefore, a number of structural molecular parameters, which depend on those interactions, become accessible. Determination of very accurate geometries of small organic molecules and the accuracy improvement of the NMR-derived structures of biomolecules are the most frequent applications of the NMR studies in anisotropic phases. Analysis of the NMR spectra of 3,5-dichlorphenylacethylene in the nematic solvent ZLI1169 has been presented as an example of the liquid crystal solvent application.

11

NMR study on conformation of 2-Benzoyl-1-methyl-3-phenylpiperidine

Szczeciński P., Gryff-Keller A.

Bulletin of the Polish Academy of Sciences. Chemistry

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2000

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Vol. 48, No. 1

13-18

EN

Temperature H NMR spectra of the title compound were measured and inter-preted in terms of slow rotation about the bond between piperidine ring and benzoyl sub-stituent. Barrier to this rotation was calculated to be Ea = 59 kJ/mol and log(A) = - 14.2.

12

Effect of planar substituents on magnetic shielding tensors of sp-hybridized carbon nuclei in substitueted acetylenes - a GIAO-CHF study

Jackowski K., Molchanov S., Gryff-Keller A.

Bulletin of the Polish Academy of Sciences. Chemistry

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2000

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Vol. 48, No. 1

77-80

EN

The magnetic shielding tensors for sp-hybridized carbons in a series of acetyl-enic compounds XC=CH (X = H, NH2, OMe, NMe2) Ph, CHO, CC1O and NO2) have been calculated using the GIAO-CHF method and the standard 6-31G** basis set. The substituent effect has appeared to be large but independent of the 7r-electronic properties of the substituent.

13

Multinuclear spin relaxation study on mercury(II) cyanide

Molchanov S., Gryff-Keller A.

Bulletin of the Polish Academy of Sciences. Chemistry

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1999

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Vol. 47, No. 1

83-88

EN

Following coupling constants for Hg(CN)2 in DMSO solution have been measured: 1J(13C-199Hg), 1 J(13C-15N), 2 J (199Hg-15N). The longitudinal (13)C and (15)N relaxation times and transverse (13(C relaxation times at two magnetic fields, and additionally the longitudinal (199)Hg relaxation time for 13C or 15(N) enriched samples have also been measured. Quantitative interpretation of those data has delivered the values of the reori-entation rate of the solute molecule and the shielding anisotropy parameters of carbon and nitrogen nuclei. Some earlier literature results concerning water solution of the inves-tigated molecule have also been commented.

14

Magnetic shielding tensors of sp-hybridized carbons in butadinyltrimethylsilane. 13C nuclear spin relaxation and ab initio study

Ejchart A., Jackowski K., Gryff-Keller A.

Bulletin of the Polish Academy of Sciences. Chemistry

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1999

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Vol. 47, No. 1

77-81

EN

Principal values of magnetic shielding tensors of acetylenic carbon nuclei for butadiynyltrimethylsilane and its reorientation rate in solution have been obtained from the interpretation of the 13C longitudinal relaxation data. The ab initio GIAO-CHF calculations of shielding parameters have been performed and the experimental and theoretical results have been compared.

15

Carbon-13 NMR study of argininosuccinic acid, the marker in an inborn error of metabolism

Krawczyk H., Gryff-Keller A.

Bulletin of the Polish Academy of Sciences. Chemistry

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1999

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Vol. 47, No. 1

21-24

EN

1H and 13C NMR spectra of barium salt of argininosuccinic acid have been recorded and interpreted. It has been pointed out that NMR spectroscopy can be a convenient method of determinatin of this acid in urine for diagnostic purposes.

16

Magnetic shielding tensors of sp-hybridized carbon nuclei

Gryff-Keller A.

Polish Journal of Chemistry

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1998

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Vol. 72, nr 2

154-162

EN

Experimental data concerning shielding tensors of the sp hybridized carbons including our own recent results have been reviewed. It appears, that the most general feature of shielding parameters for such carbons forms a linear relationship between the perpendicular chemical shift component and the isotropic chemical shift. Deviation from that interdependence informs about a distortion of the symmetry of the electron distribution around the given carbon and indirectly about various intra- or intermolecular interactons.

17

NMR investigation of the structure of fagopyritol B1 from buckwheat seeds

Szczeciński P., Gryff-Keller A., Horbowicz M., Obendorf R. L.

Bulletin of the Polish Academy of Sciences. Chemistry

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1998

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Vol. 46, No. 1

9-13

EN

Conformation of O-alfa-D-galactopyranosyl-(1 - 2)-D-chiro-inositol (fagopyritol B1) rings and linkage between galactosyl and cyclitol fragments have been investigated by different NMR technics.

18

Influence of a quadrupole nucleus of the signal of an adjacent to it 1/2 spin nucleus in high resolution NMR spectra of liquid samples

Gryff-Keller A.

Bulletin of the Polish Academy of Sciences. Chemistry

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1998

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Vol. 46, No. 1

105-115

EN

In high resolution NMR spectra of liquid samples a signal of a nucleus A (I =1/2) scalar coupled with a higher spin nucleus X reflects the relaxation properties of the latter nucleus. This signal may have the form of a singlet or a more or less resolved multiplet with characteristic relative broadenings of individual lines. Recently some spectroscopic effects, earlier predicted by theory, which manifest themselves in unsymmetrical lineshapes of the signal of A, have been reported. Measurements of the scalar relaxation of the second kind or the lineshape analysis of the A signal may provide valuable information on molecular structure and dynamics. In this paper the above phenomena have been reviewed and illustrated with experimental examples.