NQR and NMR study of hydrogen bonding interactions in anhydrous and monohydrated guanine cluster model: A computational study

• Published in: Journal of structural chemistry Vol. 50; no. 1; pp. 67 - 77
• Main Authors: Monajjemi, M., Honarparvar, B., Nasseri, S. M., Khaleghian, M.
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01.02.2009
• Subjects: Atomic; Atomic/Molecular Structure and Spectra; Chemistry; Chemistry and Materials Science; Inorganic Chemistry; Molecular; Optical and Plasma Physics; Physical Chemistry; Solid State Physics; hydrogen bonding interactions; DFT; nuclear quadrupole resonance; nuclear magnetic resonance; density functional theory
• ISSN: 0022-4766; 1573-8779
• DOI: 10.1007/s10947-009-0009-z

In this paper extensive systematic computational study has been carried out to justify hydrogen bonding interactions and their influence on the oxygen, nitrogen and hydrogen NQR and NMR parameters of the anhydrous and monohydrated guanine crystal structures at two different levels, B3LYP and MP2, using 6-311++G** and D95** basis sets. These theoretical data have been compared with experimental NMR and NQR measurements. For further investigation, results of cluster calculation have been compared with that of a single molecule. Our theoretical NQR and NMR parameters of 17 O, 15 N and 2 H atoms of anhydrous and monohydrated guanine exhibited extreme sensitivity to electron distribution around mentioned nuclei caused by cooperative influences of various types of hydrogen bonding interactions. Fortunately, our calculated isotropic shielding values and CS tensors for the 17 O and 15 N nuclei as well as obtained 14 N-NQR parameters are in excellent agreement with experimental data. Therefore, we can undoubtedly conclude that for anhydrous and monohydrated guanine tetrameric clusters including intermolecular interactions, our theoretical estimates are in better agreement with observed experimental values than those in which these interactions have been ignored.