基于IR-VUV光谱法研究分子束中一些重要天然糖类分子及其水合团簇的结构

Natural sugar molecules are a kind of important biomolecules. In the life systems, natural sugars realize its biological functions in aqueous or physiological environments. It is hard to understand the intrinsic properties of the interaction between biomolecules and solvent molecules for they were masked and equalized by the aqueous environments. The hydrated clusters containing biomolecules and solvent molecules, which was generated in a supersonic jet, would be the typical model system to research its microsolvation process and other properties related to basic physical chemistry process. For the absence of aromatic group, REMPI (Resonance Enhanced Multiphoton Ionization) is inapplicable to the natural sugar molecules. And the artificial binding an aromatic ring would distribute its intrinsic property (including its solubility properties). In present research project, we plan to detect directly and study photoionization/fragmentation process of the natural sugars molecules and its hydrated clusters in the gas phase by employing laser desorption/jet cooling, VUV single photon ionization and mass selected IR-VUV non-resonance ion-dip/enhancement spectroscopy methods. Combining with ab initio and DFT calculations, we expect to obtain some informations of those molecules, ions and their hydrated clusters' intrinsic properties such as spectra,optimal configuartions and conformations, then understand its isomerization reaction dynamics under the participation of water. The objects in present project would be the typical sugars such as deoxyribose,glucopyranose and its derivate glucosamine, oligosaccharide and their hydrated clusters.

天然糖类分子是一类重要的生物分子，均需在液相环境中实现其生物功能。由于液相环境掩盖或平均化了生物分子与溶剂分子的相互作用，很难了解其物理化学本质。通过超音速膨胀技术制备出的包含有生物分子和溶剂分子的气相团簇，可以作为研究分子微溶剂化等基本物理化学过程的模型体系。由于共振增强多光子电离无法直接对不含芳香环的天然糖类分子进行探测研究，而人为引入芳香环将影响这些分子固有性质（包括溶剂化）。本项目中拟应用激光解析/喷嘴冷却、真空紫外单光子"软电离"并结合质量选择IR-VUV非共振Ion-dip/enhancement光谱法，直接对气相中天然糖类分子及其水合团簇和它们的离子进行探测研究。结合从头算和密度泛函计算，希望获得气相中这些分子、离子及其水合团簇的光谱和分子结构，进而了解在水分子参与下它们的构象转化等动力学过程。该课题拟以脱氧核糖、葡萄糖、氨基糖、低聚糖以及它们的水合团簇作为研究的模型体系。

在该基金项目的支持下，依靠自主搭建的实验装置，我们发展了一种新的光谱检测方法，即IR-ＶＵＶ光谱方法。应用该实验装置，我们开展了分子束中二碳糖分子和其他相关生物分子及其水合团簇的红外光谱探测。结合DFT/从头算理论计算方法，最新研究发现气相中二碳糖分子及其水合团簇中，CC构型为最稳定构型。该项目还支持课题组开展了生物组织中药物分子的质谱成像研究。除此之外，我们还开展了拉曼光谱和表面增强拉曼的基础和应用研究。本项目的资助下，共发表SCI收录论文14篇,两篇中文论文。