Akita Chikayo, Kawaguchi Tatsuya, Kaneko Fumitoshi
Department of Macromolecular Science, Faculty of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.
J Phys Chem B. 2006 Mar 9;110(9):4346-53. doi: 10.1021/jp054996h.
To clarify the influence of cis-unsaturation on solid-state structures of triacylglycerols (TAGs), the crystal structures of three crystalline phases (alpha, beta' and beta) of triolein [C3H5(OCOC17H33)3] were investigated by powder X-ray diffractometry and IR and Raman spectroscopy. The influence on the structural change of the alpha phase in the course of cooling was also studied. With respect to the subcell structure and conformational order of hydrocarbon chains in the beta and beta' phases, triolein resembles saturated TAGs; trans-zigzag hydrocarbon chains are adopted in the T(parallel) subcell for the beta phase and in the O(perpendicular) subcell for the beta' phase. The influence of cis-unsaturation was most obvious in the structure of the alpha phase and its temperature dependence. The alpha phase of triolein does not form the ordinary hexagonal subcell but a rather loose distorted subcell, which hardly changes in cooling, forming a striking contrast to the hexagonal-->pseudohexagonal subcell transformation found in the alpha phase of saturated TAGs.
为阐明顺式不饱和对三酰甘油（TAGs）固态结构的影响，采用粉末X射线衍射法、红外光谱和拉曼光谱对三油精[C3H5(OCOC17H33)3]的三个晶相（α、β'和β）的晶体结构进行了研究。还研究了冷却过程中α相对结构变化的影响。关于β相和β'相中烃链的亚晶胞结构和构象有序性，三油精类似于饱和TAGs；β相的T（平行）亚晶胞和β'相的O（垂直）亚晶胞采用反式锯齿状烃链。顺式不饱和的影响在α相的结构及其温度依赖性方面最为明显。三油精的α相不形成普通的六方亚晶胞，而是形成一个相当松散的扭曲亚晶胞，在冷却过程中几乎不变，这与饱和TAGs的α相中发现的六方→伪六方亚晶胞转变形成了鲜明对比。
