Specogna Erika, Li King Wo, Djabourov Madeleine, Carn Florent, Bouchemal Kawthar
Laboratoire de Physique Thermique, ESPCI ParisTech, PSL Research University, 10 Rue Vauquelin, 75231 Paris, Cedex 5, France.
J Phys Chem B. 2015 Jan 29;119(4):1433-42. doi: 10.1021/jp511631e. Epub 2015 Jan 17.
Cyclodextrins are a family of oligosaccharides with a toroid shape that exhibit a unique ability of entrapping guest molecules in their internal cavity. Water is the primary guest molecule and is omnipresent in the crystalline phases stabilizing the overall architecture. Despite the presence of water molecules inside the cavity, cyclodextrins provide a hydrophobic environment where poorly soluble molecules can easily fit. In this investigation we put in evidence different types of water in the hydrated α-, β-, and γ-cyclodextrin crystals. Thermogravimetric measurements identify various binding sites of water and highlight the difference between the crystals equilibrated under various humid atmospheres. We establish by microcalorimetry the limit of solubility versus temperature and measure for the first time the melting temperatures of the hydrated crystals. Dissolution and melting enthalpies are derived and the solubility curves are compared to existing literature. The specific features of each cyclodextrin are underlined.
环糊精是一类呈环形的寡糖，具有将客体分子包埋在其内腔中的独特能力。水是主要的客体分子，在稳定整体结构的晶相中普遍存在。尽管腔内存在水分子，但环糊精提供了一个疏水环境，难溶性分子能够轻松适配其中。在本研究中，我们揭示了水合α-、β-和γ-环糊精晶体中不同类型的水。热重测量确定了水的各种结合位点，并突出了在不同湿度气氛下平衡的晶体之间的差异。我们通过微量热法确定了溶解度与温度的关系极限，并首次测量了水合晶体的熔化温度。推导了溶解焓和熔化焓，并将溶解度曲线与现有文献进行了比较。强调了每种环糊精的具体特征。
