Sugar acetates as CO2-philes: molecular interactions and structure aspects from absorption measurement using quartz crystal microbalance.
Sugar acetates as CO2-philes: molecular interactions and structure aspects from absorption measurement using quartz crystal microbalance.
复制标题
DOI：
10.1021/jp9122634
复制
发表时间：
2010-03
期刊：
影响因子：
--
通讯作者：
Shaoling Ma;You‐Ting Wu;Michael L Hurrey;S. Wallen;C. Grant
中科院分区：
文献类型：
--
作者：
Shaoling Ma;You‐Ting Wu;Michael L Hurrey;S. Wallen;C. Grant
糖乙酸酯是一种具有吸引力的亲CO（2）化合物，在CO（2）为基础的过程中，作为药物赋形剂、控释剂和微乳液体系的表面活性剂具有潜在的用途。本研究以石英晶体微天平（QCM）为检测器，对这些糖衍生物吸收高压CO2的过程进行了定量研究。除了吸收测量外，QCM最初被发现能够检测CO（2）诱导的糖乙酸酯的潮解，并且潮解发生时的CO（2）压力取决于几个影响因素，如温度和膜厚度。α-D-葡萄糖五乙酸酯对CO（2）的吸收（Ac-alpha-GLU）与其异头物Ac-beta-GLU相比显示出更大的数量级，而α-D-半乳糖五乙酸酯（Ac-alpha-GAL）由于异头和C4碳上的乙酰基之间的空间位阻而比Ac-alpha-GLU吸收更少的CO（2），这意味着醋酸糖的分子结构和构型对吸收至关重要。考察了糖醋酸酯分子大小和乙酰基数对CO（2）吸收的影响，结果表明，结晶糖醋酸酯的构象和堆积以及乙酰基的可及性对CO（2）的吸收也是至关重要的。另外还发现，CO（2）诱导的结构从晶态系统到非晶态系统的变化导致CO（2）吸收的数量级增加。进一步的研究通过计算热力学参数如亨利定律常数、溶解焓和溶解熵来说明糖乙酸酯与CO（2）之间的相互作用强度。实验和计算表明，糖乙酸酯表现出高的CO（2）吸收，至少与离子液体相当。由于离子液体在酸性气体分离中具有潜在的应用，因此从本研究中可以看出，糖乙酸酯可以用作分离CO（2）的可能材料。
Sugar acetates, recognized as attractive CO(2)-philic compounds, have potential uses as pharmaceutical excipients, controlled release agents, and surfactants for microemulsion systems in CO(2)-based processes. This study focuses on the quantitative examination of absorption of high pressure CO(2) into these sugar derivatives using quartz crystal microbalance (QCM) as a detector. In addition to the absorption measurement, the QCM is initially found to be able to detect the CO(2)-induced deliquescence of sugar acetates, and the CO(2) pressure at which the deliquescence happens depends on several influencing factors such as the temperature and thickness of the film. The CO(2) absorption in alpha-D-glucose pentaacetate (Ac-alpha-GLU) is revealed to be of an order of magnitude larger in comparison with its anomer Ac-beta-GLU, whereas alpha-D-galactose pentaacetate (Ac-alpha-GAL) absorbs CO(2) less than Ac-alpha-GLU due to the steric-hindrance between the acetyl groups on the anomeric and C4 carbons, implying the significant importance of the molecular structure and configuration of sugar acetates on the absorption. The effects of molecular size and acetyl number of sugar acetates on the CO(2) absorption are evaluated and the results indicate that the conformation and packing of crystalline sugar acetate as well as the accessibility of the acetyls are also vital for the absorption of CO(2). It is additionally found that a CO(2)-induced change in the structure from a crystalline system to an amorphous system results in an order of magnitude increase in CO(2) absorption. Further investigation illustrates the interaction strength between sugar acetates and CO(2) by calculating the thermodynamic parameters such as Henry's law constant, enthalpy and entropy of dissolution from the determined CO(2) absorption. Experiments and calculations demonstrate that sugar acetates exhibit high CO(2) absorption, as at least comparable to ionic liquids. Since the ionic liquids have potential uses in the separation of acidic gases, it is evident from this study that sugar acetates could be used as possible materials for CO(2) separation.