Gerig J T
Department of Chemistry & Biochemistry, University of California-Santa Barbara, Santa Barbara, California 93106, USA.
J Org Chem. 2003 Jun 27;68(13):5244-8. doi: 10.1021/jo026599y.
Nuclear Overhauser effects arising from the interactions of spins of solvent molecules with spins of a solute should reveal the "exposure" of solute spins to collisions with solvent. Such intermolecular NOEs could, therefore, provide information regarding conformation or structure of the solute. Determinations of solute-solvent NOEs of 1,3-di-tert-butylbenzene in solvents composed of perfluoro-tert-butyl alcohol, tetramethylsilane, and carbon tetrachloride have been carried out. A crude, but apparently reliable, method for prediction of intermolecular solvent-solute NOEs based on hard (noninteracting) spheres was developed. Comparison of experimental to predicted NOEs indicates that tetramethylsilane interacts with the solute according to the model. By contrast, intermolecular NOE data indicate attractive interactions between the solute and perfluoro-tert-butyl alcohol. All NOE results and the corresponding predictions confirm that proton H2 of the solute is protected by the flanking tert-butyl groups from interactions with solvent molecules.
由溶剂分子的自旋与溶质的自旋相互作用产生的核Overhauser效应，应能揭示溶质自旋与溶剂碰撞时的“暴露”情况。因此，这种分子间的核Overhauser效应能够提供有关溶质构象或结构的信息。已对1,3 -二叔丁基苯在由全氟叔丁醇、四甲基硅烷和四氯化碳组成的溶剂中的溶质 - 溶剂核Overhauser效应进行了测定。基于硬（非相互作用）球体开发了一种粗略但显然可靠的预测分子间溶剂 - 溶质核Overhauser效应的方法。实验测定的核Overhauser效应与预测值的比较表明，四甲基硅烷与溶质的相互作用符合该模型。相比之下，分子间核Overhauser效应数据表明溶质与全氟叔丁醇之间存在吸引相互作用。所有核Overhauser效应结果及相应预测均证实，溶质的质子H2受到侧翼叔丁基的保护，免受与溶剂分子的相互作用。
