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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

2009

Vol. 83, nr 5

857-868

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.

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

2006

Vol. 80, nr 11

1831-1843

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.