| Summary: | 碩士 === 國立成功大學 === 化學工程學系 === 102 === Two dimeric pyridine derivatives containing cholesteryl group were synthesized. The connecting group between cholesterol and pyridine contains benzene rings and amide groups. The structures of the compounds are changed by varying the relative positions of amide groups on the benzene rings (at para and meta). Gelation properties of the synthesized two compounds (PyPC and PyMC) were studied. From gelation results, PyMC has higher gelation ability than PyPC. The results suggest that connecting position affect polarity of molecules, thus it leads to the difference of molecular interaction resulting in different gelation behavior of the two compounds. The morphologies and packing arrangements of xerogels were studied using SEM, TEM, 1H-NMR, XRD, and CD spectra. SEM measurements observe the formation of nanotube structures with helical structures. TEM measurements reveal that the molecular structures, nature of solvents show significant effect on the morphologies of the gel networks. It was observed that PyPC in dodecanol forms nanotube structures in which the nanotubes were constructed by twisted fibers. Interestingly, TEM observations show that both left and right handed helical constructions were formed although the system is chiral system. However, CD analysis indicates the existence of helical constructions. The results suggest that both left and right handed helical constructions shown in TEM images should be unequal amount.
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