New azobenzene liquid crystal with dihydropyrazole heterocycle and photoisomerization studies
New azobenzene liquid crystal with dihydropyrazole heterocycle and photoisomerization studies
复制标题
DOI：
10.1098/rsos.200474
复制
发表时间：
2020-07
影响因子：
3.5
通讯作者：
Xiaoxuan Wang;Z. Li;Haiying Zhao;Shufeng Chen
中科院分区：
文献类型：
--
作者：
Xiaoxuan Wang;Z. Li;Haiying Zhao;Shufeng Chen
制备并表征了新的二氢吡唑杂环偶氮苯衍生物。根据热偏光显微镜和差示扫描量热法研究，由四个线性连接的环和偶氮苯侧的长烷氧基链组成的化合物（3a-8和3a-14）不显示液晶特性。当介晶单元长度增加到5环时，除化合物5a-8外，酯基侧含有10-16个碳原子长链的化合物5a-10至5a-16均表现出液晶性质，且介晶域随着链长的增加而逐渐变窄。然而，在两侧具有长烷氧基链的分子的情况下，只有具有16个碳原子长链的5c-16表现出液晶行为。此外，这些偶氮化合物在紫外线照射下发生E异构化至Z异构化，然后在黑暗中缓慢热回弛豫，可多次循环利用。
New azobenzene derivatives with dihydropyrazole heterocycle have been prepared and characterized. According to thermal polarizing microscopy and differential scanning calorimetry studies, the compounds consisting of four linearly linked rings and a long alkoxy chain on the azobenzene side (3a-8 and 3a-14) displayed no liquid crystal properties. When the length of mesogenic unit increased to five rings, except for compound 5a-8, all compounds from 5a-10 to 5a-16 containing a long chain of 10–16 carbon atoms on the side of ester group displayed liquid crystalline properties, and the mesogenic domain gradually narrowed with increase of the chain length. However, in the case of the molecule with long alkoxy chains on both sides, only 5c-16 with a long chain of 16 carbon atoms exhibited liquid crystal behaviour. In addition, these azo compounds underwent isomerization from E to Z under ultraviolet irradiation and then thermal back relaxation slowly in the dark, which can be recycled many times.