Synthesis and characterization of bent-shaped liquid crystals containing azobenzene as mesogenic cores

Law, Soon Pin (2010) Synthesis and characterization of bent-shaped liquid crystals containing azobenzene as mesogenic cores. Universiti Malaysia Sabah. (Unpublished)


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The objectives of this thesis are to synthesis and characterize a bent-shaped liquid crystals containing azobenzene as mesogenic. Fourier Transform Infrared (FT-IR) spectrometer was used to determine the functional groups and photochemical properties of the intermediates and final compounds. Differential scanning calorimetry (DSC) was used to determine the thermal behavior of the liquid crystal and ultraviolet visible (UV-Vis) leaded to the photoisomerization and photochromic behavior. Starting material was ethyl4-amino benzoate, It undergo diazonium coupling reaction with phenol to produce ethyl4-(4-hydroxyphenylazo) benzoate. This product continued reacted via Williamson type ether synthesis to produce ethyl4-( 4-hexadecyloxyphenytazo) benzoate. The ester functional group (benzoate) was proceeded to base-cataIyzed hydrolysis with potassium hydroxide to get ethyl4-( 4 hexadecyloxyphenyIazo)benzoic add. Final synthesizing step was the esterification with resorcinol, together with a catalyst, 4-dimethylamlnopyridlne (DMAP) and dehydrating agent, 1,3-dicyclohexyk:arbodlimide (DCC) to produce 1,3- phenytene bis[4-(4-hexadecyIoxyphenylazo)]benzoate. All functional groups in the moIecular structures of each compound were confirmed by FTIR. Ultraviolet visible (UV-Vis) spectrum showed three absorption peaks d maximum absorbance at approximate value of 259.35, 366.06, 459.44nm respectively. However, excessive addition amount of resorcinol resulting the presence of a free hydroxyl (-OH) peak in the IR spectrum. Differential scanning calorimetry (DSC) thermogram of the final product proved the preence of mesophase, therefore, the synthesis d liquid crystal is considered as successful.

Item Type: Academic Exercise
Uncontrolled Keywords: fourier Transform Infrared, Differential scanning calorimetry, liquid crystal
Subjects: Q Science > QD Chemistry
Divisions: SCHOOL > School of Science and Technology
Depositing User: Unnamed user with email
Date Deposited: 18 May 2016 05:34
Last Modified: 30 Oct 2017 02:43

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