Boulet Béatrice, Joubert Laurent, Cote Gérard, Bouvier-Capely Céline, Cossonnet Catherine, Adamo Carlo
Laboratoire d'Electrochimie et Chimie Analytique, UMR CNRS-ENSCP 7575, Ecole Nationale Supérieure de Chimie de Paris, France.
J Phys Chem A. 2006 May 4;110(17):5782-91. doi: 10.1021/jp0565305.
An experimental and theoretical study on the conformational behavior of the 1,3,5-OMe-2,4,6-OCH(2)CONHOH-p-tert-butylcalix[6]arene has been carried out. In particular, semiempirical (AM1) and density functional theory (DFT) calculations have been performed in order to identify the possible conformers. The obtained results show that the cone structure is the most stable conformer at any level of theory, even if significant differences have been obtained for the other species. The inclusion of solvent effect, through a continuum model, also points out the relevant role played by the solvent in the stabilization of the cone structure in solution. These latter results have been confirmed by NMR experiments, which clearly show the presence of only the cone conformer in a polar solvent, such as DMSO. Finally, (1)H and (13)C NMR spectra on model systems, i.e., two successive phenol rings (Ar(1)-CH(2)-Ar(2)), have been computed at the DFT level and compared with the experimental spectra of the complete molecule. The results show an overall good agreement with the experimental data, thus leading to an unambiguous assignment of the experimental spectra.
对1,3,5-OMe-2,4,6-OCH(2)CONHOH-对叔丁基杯[6]芳烃的构象行为进行了实验和理论研究。特别是，进行了半经验（AM1）和密度泛函理论（DFT）计算，以确定可能的构象异构体。所得结果表明，在任何理论水平下，锥形结构都是最稳定的构象异构体，即使其他异构体存在显著差异。通过连续介质模型考虑溶剂效应，也指出了溶剂在溶液中锥形结构稳定化中所起的重要作用。这些结果已通过核磁共振实验得到证实，该实验清楚地表明在极性溶剂（如DMSO）中仅存在锥形构象异构体。最后，在DFT水平上计算了模型体系（即两个连续的酚环（Ar(1)-CH(2)-Ar(2)））的(1)H和(13)C核磁共振谱，并与完整分子的实验谱进行了比较。结果表明与实验数据总体吻合良好，从而实现了对实验谱的明确归属。
