Temperature-dependent molecular motions and phase behavior of cholesteryl ester analogues.
Temperature-dependent molecular motions and phase behavior of cholesteryl ester analogues.
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发表时间：
1987-12
影响因子：
6.5
通讯作者：
D. Croll;P. K. Sripada;J. Hamilton
中科院分区：
文献类型：
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作者：
D. Croll;P. K. Sripada;J. Hamilton
对三种胆固醇醚（己酰基、肉豆蔻基、油基）和胆固醇碳酸酯（油基）的相行为和温度依赖性分子运动进行了表征。每种醚的性质与相应的胆固醇酯在性质上相似，但在数量上不同。例如，胆甾醇油基醚表现出与胆甾醇油酸酯相同的相变，但温度低得多（例如，醚各向同性液体到胆甾醇的转变是在 29 摄氏度）。各向同性液体和液晶相中醚的 13C NMR 谱与酯类似物的相似。然而，在液体到液晶转变附近，醚的类固醇环C3和C6线宽、C3/C6线宽比以及从线宽计算出的类固醇环旋转相关时间tau rx和tau rz比酯类似物大。油烯基碳酸酯与其类似物具有性质不同的性质（例如，稳定与亚稳定胆甾相和近晶相）。碳酸酯的定量结果（例如，各向同性液相中相对较长的 tau rx 和 tau rz）也与酯和醚类似物的定量结果不同。通过对极性键是唯一结构变量的类似物进行比较，可以深入了解影响相行为的分子间相互作用。
The phase behavior and temperature-dependent molecular motions of three cholesteryl ethers (caproyl, myristyl, oleyl) and a cholesteryl carbonate (oleyl) were characterized. The properties of each ether were qualitatively similar to, but quantitatively different from, those of the corresponding cholesteryl ester. For example, cholesteryl oleyl ether exhibited the same phase transitions as cholesteryl oleate, but at much lower temperatures (e.g., the ether isotropic liquid to cholesteric transition is at 29 degrees C). 13C NMR spectra of ethers in the isotropic liquid and liquid crystalline phases were similar to those of the ester analogue. However, near the liquid to liquid crystalline transition, the steroid ring C3 and C6 linewidths, the C3/C6 linewidth ratio, and the steroid ring rotational correlation times tau rx and tau rz calculated from the linewidths were larger for the ether than the ester analogue. The oleyl carbonate had qualitatively different properties from its analogues (e.g., stable vs. metastable cholesteric and smectic phases). Quantitative results (e.g., relatively long tau rx and tau rz in the isotropic liquid phase) for the carbonate were also distinct from those of both the ester and ether analogues. A comparison of analogues in which the polar linkage is the only structural variable yielded insights into the intermolecular interactions which influence phase behavior.