Strength from Weakness: Conformational Divergence between Solid and Solution States of Substituted Cyclitols Facilitated by CH···O Hydrogen Bonding
作者:Amol M. Vibhute、Kana M. Sureshan
DOI:10.1021/jo5004778
日期:2014.6.6
calculate the dihedral angle (ϕ) between the respective vicinal protons. By fixing the dihedral angle between different sets of vicinal protons, the molecules were energy-minimized by MM2 method to visualize their conformation in solution. As the solvent polarities can influence the conformational preference, we have determined the conformations of these molecules in various solvents of different polarities
我们已经调查了一系列环醇衍生物的1,2构象的偏好,即单和二酯:5,6-二Ø异亚丙基肌醇和肌醇1,2:5,6二Ø亚环己基-肌醇-固态和溶液态。固态构象通过单晶X射线分析确定。通过使用NMR确定溶液状态的构象。实验3 J HH在Haasnoot-Altona方程中应用这些值来计算各个相邻质子之间的二面角(ϕ)。通过固定不同组相邻质子之间的二面角,通过MM2方法对分子进行能量最小化以可视化其在溶液中的构象。由于溶剂极性会影响构象偏好,因此我们确定了这些分子在不同极性的各种溶剂中的构象,例如苯-d 6,氯仿-d,乙腈-d 3,丙酮-d 6,甲醇-d 4,和DMSO- d 6。所有化合物在溶液中均采用舟状构型,而与溶剂,酰基或亚烷基保护基无关。该构象将环糖醇环的H6和O3放置在附近,从而使它们之间的分子内CH··O氢键稳定了这种原本不稳定的构象。但是,在固态状态下,几个分子间的CH···O氢键迫使这