Syntheses, Self-assembly, and Kinetics of Photo-responsive 1,4-Bistriazolyl- azobenzene Bridged Biscalix[4]arene Derivatives

• Main Authors: Huang, Yu-Pei, 黃瑜珮
• Other Authors: Chung, Wen-Sheng
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/48468637958255143123

碩士 === 國立交通大學 === 應用化學系碩博士班 === 103 === Gelator molecules usually contain long alkyl chains to increase the van der Waals interaction among them. However, we have previously reported a serendipitous discovery that isoxazole bridged biscalix[4]arene without any long alkyl chains forms gel in certain conditions. Besides, in our previously group reseach thesis of Ms. Su, we introduced azobenzene to synthesize azobenzene bridged biscalix[4]arene derivatives which can be used to form photo responsive organogelators. In this thesis, we synthesize the lower and the upper-rim azobenzene bridged biscalix[4]arenes without tert-butyl group by the click reaction to study the function of the tert-butyl and the hydroxyl group of calix[4]arene in forming gels. According to the results, we find compound 45 only in benzene and compound 46 only in n-butanol can form gel. It means van der Waals interactions among the tert-butyl groups play an important role in forming gels. The variable-temperature 1H-NMR, variable-temperature absorption spectra, PXRD, SEM, TEM, and IR spectroscopy are used to gain our understanding of possible packing models of compound 45 and 46. Furthermore, we study the thermally induced cis-trans isomerization of a series of azobenzene-bridged macrocycles. On the basis of the literatures, two mechanisms—rotation and inversion, have been proposed as possible pathways for azobenzene thermal isomerization. We suspect that the activation energies will be affected by the macrocycles at the para position. According to the results, we propose two possible viewpoints. First, the results shows the energy barrier of these compounds slightly increase as the molecular weights increase. It means the rotation mechanism may happen. In other word, the size of substitutes will influence on the isomerization of azobenzene derivatives. Second, we study about the electronic effect of the substituents. We find the activation energies become smaller as the electron-withdrawing effect increases. The results indicate the inversion mechanism works in this place. Hence, electronic effect plays a crucial role on the energy barrier of the thermally induced cis-trans isomerization of the azobenzene. The mechanisms of these azobenzene-bridged macrocycles still remain to be discussed further, and the computational calculations is worthy of studying.