Da Silva Eric, Bresson Serge, Rousseau Dérick
Department of Chemistry and Biology, Ryerson University, 350 Victoria St., Toronto, Ontario M5B2K3, Canada.
Chem Phys Lipids. 2009 Feb;157(2):113-9. doi: 10.1016/j.chemphyslip.2008.11.002. Epub 2008 Nov 13.
Raman spectroscopy was used to distinguish the differences in the molecular organization of the alpha, beta' and beta polymorphs, as well as the liquid state, of tristearin with focus placed on the C=O, C-H and C-C Raman-active stretching regions. The ester carbonyl stretching region permitted polymorphic discrimination due to significant differences in the number of modes, their relative frequencies and their full-widths at half-maximum. In the liquid state, the absence of obvious signatures in this region indicated that many local micro-environments likely exist about the ester carbonyl of molten tristearin. The ratio between the symmetrical and asymmetrical C-H stretching modes was linearly correlated with the enthalpy of fusion for each polymorph. The C-C stretching modes, which provided insight into the trans/gauche content, were polymorph independent, but changed significantly upon transition into the liquid state (p < 0.05). Overall, Raman spectroscopy allowed for the quick discrimination of tristearin polymorphs from a conformational and thermodynamic perspective.
拉曼光谱用于区分三硬脂酸甘油酯的α、β′和β多晶型以及液态在分子结构上的差异，重点关注C=O、C-H和C-C拉曼活性伸缩区域。由于模式数量、相对频率及其半高宽存在显著差异，酯羰基伸缩区域可用于多晶型鉴别。在液态下，该区域没有明显特征，这表明熔融三硬脂酸甘油酯的酯羰基周围可能存在许多局部微环境。每种多晶型的对称和不对称C-H伸缩模式之间的比率与熔化焓呈线性相关。C-C伸缩模式可深入了解反式/ gauche含量，它与多晶型无关，但在转变为液态时发生了显著变化（p < 0.05）。总体而言，拉曼光谱能够从构象和热力学角度快速鉴别三硬脂酸甘油酯的多晶型。
