13C Chemical Shift Tensors in Hypoxanthine and 6-Mercaptopurine : Effects of Substitution, Tautomerism, and Intermolecular Interactions
| Authors | |
|---|---|
| Year of publication | 2010 |
| Type | Article in Periodical |
| Magazine / Source | The Journal of Physical Chemistry A |
| MU Faculty or unit | |
| Citation | |
| Web | DOI: 10.1021/jp9100619 |
| Doi | http://dx.doi.org/10.1021/jp9100619 |
| Field | Physical chemistry and theoretical chemistry |
| Keywords | solid-state NMR; DFTcalculations; X-ray powder diffraction; hydrogen bonding; stacking interactions |
| Attached files | |
| Description | Principal values of the 13C chemical shift tensor (CST) are measured for two biologically interesting and structurally related compounds, hypoxanthine and 6-mercaptopurine, and differences in the values are discussed with an attempt to reveal chemical shifts sensitive to substitution and prototropic tautomerism in the purine ring. Furthermore, methods of density-functional theory (DFT) are used to calculate principal values of the 13C chemical shift tensor and orientations of the principal components. Values calculated for isolated molecules are compared to those for several supramolecular clusters and then to experimental data to investigate the degree of modulation of the 13C CSTs by molecular packing. Focusing on the protonated carbons, C2 and C8, which are crucial for relaxation measurements, we show that neglecting intermolecular interactions can lead to errors as large as 30 ppm in the delta22 principal component. |
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