Jin Shan, Hu Yongjun, Wang Pengchao, Zhan Huaqi, Lu Qiao, Liu Fuyi, Sheng Liusi
MOE Key Laboratory of Laser Life Science & Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou 510631, P. R. China.
Phys Chem Chem Phys. 2018 Mar 7;20(10):7351-7360. doi: 10.1039/c7cp07935d.
Water molecules, which serve as both hydrogen bond donors and acceptors, have been found to influence the conformational landscape of gas-phase phenyl-β-d-glucopyranoside. Herein, tetrahydrofurfuryl alcohol (THFA), a sugar-like molecule without chromophores (e.g. phenyl-substitution), was used as the model sugar molecule for exploring the behaviour of water molecules on the conformational landscape of a pentose sugar such as deoxyribose. We used mass selected infrared-vacuum ultraviolet (IR-VUV) (118 nm) spectroscopy to investigate the hydrated neutral THFA and its complex cation in a supersonic jet. High level density functional theory (DFT) calculations were performed to ascertain the experimental results. The results revealed that the water molecule tends to insert into the twisted conformer at a position where two stronger intermolecular hydrogen bonds were formed by breaking the weak intramolecular interactions. We found that the twisted conformer of the hydrated neutral THFA complex is more stable than the envelope conformation, while the latter is more stable for the THFA molecule. However, the conformational landscape of the hydrated THFA complex cation did not significantly change on microsolvation with water molecules. These results indicated that the dominant structural landscape of the hydrated cationic complex is the twisted configuration with a trans-hydroxymethyl group. This finding provides valuable insight into the microsolvation of gas-phase sugar molecules.
水分子既能作为氢键供体，又能作为氢键受体，已被发现会影响气相苯基-β-D-吡喃葡萄糖苷的构象态势。在此，四氢糠醇（THFA），一种没有发色团（如苯基取代）的类糖分子，被用作模型糖分子，以探究水分子在脱氧核糖等戊糖构象态势上的行为。我们使用质量选择红外-真空紫外（IR-VUV）（118纳米）光谱来研究超声速射流中含水合的中性THFA及其复合阳离子。进行了高水平密度泛函理论（DFT）计算以确定实验结果。结果表明，水分子倾向于插入扭曲构象体中通过打破弱分子内相互作用形成两个较强分子间氢键的位置。我们发现，含水合的中性THFA络合物的扭曲构象体比信封构象更稳定，而对于THFA分子而言，后者更稳定。然而，含水合的THFA复合阳离子的构象态势在与水分子进行微溶剂化时没有显著变化。这些结果表明，水合阳离子络合物的主要结构态势是具有反式羟甲基基团的扭曲构型。这一发现为气相糖分子的微溶剂化提供了有价值的见解。
