Calculation of NMR Chemical Shifts and Spin−Spin Coupling Constants in the Monosaccharide Methyl-β-d-xylopyranoside Using a Density Functional Theory Approach

Abstract

Density functional theory based approaches were used to calculate chemical shieldings and spin−spin coupling constants in a monosaccharide, methyl-β-d-xylopyranoside. Excellent agreement was found between the computed and experimental data for this monosaccharide both in solution and in solid state. The effect of torsion around the C1−O1 bond showed that chemical shifts of the anomeric proton, both ring and O1 oxygens as well as C1, C2, and the methyl carbons, strongly depend on the dihedral angle. Similarly, both one-bond and three-bond proton−carbon coupling constants among anomeric proton and anomeric and methyl carbons [(1 J C1 - H1) and (3 J C(Me) - H1), respectively] showed a dependence on the torsion angle Φ.

Metabolic transformations of acquired lucibufagins by firefly “femmes fatales”

“…As expected, the DQF-COSY spectra of 10 showed signals corresponding to the steroidal skeleton and the pyrone ring of a lucibufagin (Table 3). Furthermore, the spectra indicated the presence of an additional spin system, consisting of 6 protons with chemical shift values between l 3.16 and 4.34, which corresponded to a xylopyranosyl substituent (Hricovini et al 1997).…”

The quantum-chemical calculation of NMR indirect spin–spin coupling constants

“…The first successful (and still popular) implementation of KohnSham theory for the calculation of indirect nuclear spin-spin coupling constants was that of Malkin et al [83][84][85], at the LDA and GGA levels of theory. In their code, the FC contribution to the spin-spin coupling constant was obtained by finite perturbation theory (FPT) and the SD term was omitted, although the important SD-FC contribution to the spin-spin coupling anisotropy was obtained by FPT.…”

Effect of rotation and vibration on nuclear magnetic resonance chemical shifts: Density functional theory calculations

“…This DFT based SOS-DFPT method is fast and accurate: for molecules for which correlation is relatively unimportant it is almost as good as MP2 and for molecules with strong correlation effects it is significantly more reliable 7,20 and much faster than MP2. As a result, this method is now used for studies of large transition metal complexes, 21-23 biological systems, [24][25][26] and solvation effects. 27 For many of these systems the effects of nuclear motion on shielding constants ͑and, in general, the dependence of shielding constants on structural parameters͒ are important.…”