A theoretical investigation of hydrogen bonding effects on oxygen and hydrogen chemical shielding tensors of aspirin

• DOI: 10.1007/s11224-011-9810-3
• Publication Date: 2011-05-31T06:06:35Z
• Authors: Mehdi D. Esrafili; Vahideh Alizadeh
• Keywords: Chemical shift

A computational investigation was carried out to characterize the 17O and 1H chemical shielding (CS) tensors in crystalline aspirin. It was found that O–H⋯O and C–H⋯O hydrogen bonds around the aspirin molecule in the crystal lattice have a different influence on the calculated 17O and 1H CS eigenvalues and their orientations in the molecular frame of axes. The calculations were performed with the BLYP, B3LYP, and M06 functionals employing 6-311++G(d,p) standard basis set. Calculated CS tensors were used to evaluate the 17O and 1H chemical shift isotropy (δiso) and anisotropy (Δσ) in crystalline aspirin, which are in reasonable agreement with available experimental data. The difference between the calculated NMR parameters of the monomer and molecular clusters shows how much hydrogen-bonding interactions affect the CS tensors of each nucleus.