Dipartimento di Scienze Chimiche, Università di Cagliari, Complesso Universitario, S.S. 554, Bivio per Sestu, I-09042 Monserrato (CA), Italy.
Magn Reson Chem. 2009 Oct;47(10):862-7. doi: 10.1002/mrc.2488.
The torsion angle effect on the isotropic shielding of (17)O nucleus in alpha,beta-unsaturated carbonyl groups is studied by means of density functional theory (DFT) calculations using a polarizable continuum model (PCM) for the solvent, employing the PBE0 functional together with the 6-311G(d,p) basis set for geometry optimization, and the 6-311+G(2d,p) basis set for calculating the NMR shielding with the gauge-including atomic orbitals (GIAO) method.This study adds new information on the sensitivity of the (17)O nucleus to conformational changes, revealing a strong dependence of the (17)O NMR chemical shift on the dihedral angle between the carbonyl and the vinyl moiety in all studied compounds; remarkable differences are observed with the data reported for alpha-diketones.
通过密度泛函理论（DFT）计算，采用极化连续模型（PCM）来模拟溶剂，使用 PBE0 泛函和 6-311G(d,p)基组进行几何优化，并使用包含自洽原子轨道（GIAO）方法的 6-311+G(2d,p)基组计算 NMR 屏蔽，研究了（17）O 核在α，β-不饱和羰基中的各向同性屏蔽的扭转角效应。本研究为（17）O 核对构象变化的敏感性提供了新的信息，揭示了在所有研究的化合物中，（17）O NMR 化学位移与羰基和乙烯基部分之间的二面角强烈相关；与报道的α-二酮数据相比，观察到显著差异。
