Studies on Microwave Assisted Synthesis and Substituent Effects of Ester Type Banana-Shaped Liquid Crystals
Date Issued
2005
Date
2005
Author(s)
Hsu, Te-Jung
DOI
zh-TW
Abstract
Abstract
In the first section of this thesis, we have probed into how the terminal phenyl ring of a banana-shaped molecule affects its liquid crystal property. We have synthesized a variety of banana-shaped molecules with different substituents and altering side chains. Except for F and NO2 groups, other sorts of substituents (including CH3, CN, Cl, OCH3 and OC2H5) would annihilate the liquid crystal character. This outcome reveals that substituents in the terminal phenyl ring would appreciably interrupt the intermolecular stacking and thus diminish the stability of the mesophase even destroy the mesogen’s formation. Nevertheless, F and NO2 groups, by inducing dipoles to increase the intermolecular attraction, would evoke the mesogenic nature. Eventually, neither changing the classification of the lateral side chain nor varying its position would cause a liquid crystal.
Moreover, instead of the common covalent bond, we synthesized a series of banana-shaped molecules via hydrogen bonding. We have found that the direction and the electron pulling or pushing quality would indeed influence the liquid crystalline and we have explained this effect through theoretical calculation.
At the last, we utilized the microwave to synthesize all the aimed products in place of the traditional heating procedure. Meanwhile, we have compared these two avenues at the points of solvent requirement, time consuming, and energy saving.
Subjects
液晶
微波
取代基
香蕉形
liquid crystal
banana shaped
microwave
substituent
Type
thesis
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