New Mesogenic Schiff Base Esters with Polar Chloro Substituent: Synthesis, Thermotropic Properties and X-Ray Diffraction Studies | Science Publications

American Journal of Applied Sciences

Guan-Yeow Yeap¹  Yasodha Sivasothy¹  Hong-Cheu Lin¹  Lay-Khoon Ong¹  Peng-Lim Boey¹  Sie-Tiong Ha¹ 

关键词: Azomethine;    liquid crystal;    smectic A;    smectic B;    X-ray diffraction;   

DOI  :  10.3844/ajassp.2010.214.220

学科分类：自然科学（综合）

来源: Science Publications

【 摘 要 】

Problem statement: Many studies have been conducted on the Schiff bases alkyl and alkyloxy possessing terminal halogen substituent. However, the thermotropic properties of Schiff bases ester (or alkanoyloxy) with chloro terminal group remained unstudied.Approach: Synthesis a series of new Schiff base ester possessing polar chloro group and investigate its mesomorphic properties. The title compounds were prepared via condensation and esterification reactions. The molecular structures were confirmed using spectroscopic techniques. All the members are differed by the length of alkanoyloxy chain, C_n-1H_2n-1COO, where n = 2-8, 10, 12, 14, 16 and 18. The mesomorphic properties were studied using differential scanning calorimetry, polarizing optical microscopy and temperature-dependent X-ray diffractometry. Results: Whilst short members (n = 2-5) were not mesogenic compounds, n-hexanoyloxy and n-heptanoyloxy derivatives exhibited monotropic SmA and SmB phases. Enantiotropic smectogenic A and monotropic smectogenic B were observed in n-octanoyloxy to n-hexadecanoyloxy derivatives. Highest member of the series, n-octadecanoyloxy derivatives exhibited monotropic SmA phase. Conclusion: The ester linkage and polar terminal group in the present series are essential for the formation of liquid crystal phase in Schiff bases.

【 授权许可】

Unknown