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.

已经制备并表征了具有二氢吡唑杂环的新的偶氮苯衍生物。根据热偏振显微镜和差示扫描量热法研究，由四个线性连接的环和在偶氮苯侧（3a-8和3a-14）的长烷氧基链组成的化合物没有显示出液晶性质。当介晶单元的长度增加到5个环时，除了化合物5a-8之外，所有化合物均从5a-10到5a-16在酯基一侧含有10-16个碳原子长链的分子具有液晶性质，随着链长的增加，介晶域逐渐变窄。然而，在分子的两面都具有长烷氧基链的情况下，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从E到Z异构化，然后在黑暗中缓慢回热，可以多次循环使用。