Department of Chemistry, Faculty of Science, University of Malaya, 50603, Kuala Lumpur, Malaysia.
Department of Chemistry, Sharif University & Technology, P.O. Box 11365-9516, Tehran, Iran.
J Mol Model. 2021 Oct 9;27(11):315. doi: 10.1007/s00894-021-04916-9.
Rare sugars are monosaccharides with tremendous potential for applications in pharmaceutical, cosmetics, nutraceutical, and flavors industries. The four rare sugars, including gulose, allose, altrose, and talose, are stereoisomers that are different in the hydroxyl group orientation (axial or equatorial) on the C atoms. The basis sets effect in evaluation of the possibility intramolecular hydrogen bonding (H-bonds) in the selected rare sugars was studied from 6-31G* to 6-311 ++ G(d,p) basis sets using DFT, AIM, and NBO methods. The results show that the selected rare sugars are more stable at 6-311 ++ G(d,p) basis sets compared to 6-31G* because their electronic energies were reduced between 158 and 164 (kcal.mol). The overall effect of basis set enhancement is to decrease H-bond energies in the range of 1.25 to 2.51 (kcal.mol) and stabilization energies between 2 and 5 (kcal.mol) in the selected rare sugars at the DFT level of theory. The intramolecular H-bond distances, H-bond energies obtained from the AIM analysis, and also the second-order stabilization energies obtained from the NBO analysis were fluctuated largely depending on the basis set. In summary, it was found that the use of 6-311 ++ G(d,p) basis set to be more efficient results in rare sugars geometry than the 6-31G* basis set.
稀有糖是单糖，具有在制药、化妆品、营养保健品和香料行业应用的巨大潜力。四种稀有糖，包括古洛糖、阿洛糖、阿卓糖和塔罗糖，是在碳原子上羟基方向（轴向或赤道）不同的立体异构体。使用 DFT、AIM 和 NBO 方法，从 6-31G* 到 6-311 ++ G(d,p) 基组研究了评估所选稀有糖中分子内氢键（H-bonds）可能性的基组效应。结果表明，与 6-31G* 相比，所选稀有糖在 6-311 ++ G(d,p) 基组中更稳定，因为它们的电子能降低了 158 到 164（kcal.mol）。基组增强的总体效果是降低所选稀有糖中 H-bond 能量范围在 1.25 到 2.51（kcal.mol）之间，稳定能在 2 到 5（kcal.mol）之间，在 DFT 理论水平上。从 AIM 分析得到的分子内 H-bond 距离、H-bond 能量，以及从 NBO 分析得到的二阶稳定化能量，很大程度上取决于基组。总之，研究发现使用 6-311 ++ G(d,p) 基组比 6-31G* 基组更有效，从而得到稀有糖的几何结构。
