3＇,5＇-二溴-3-甲氧基-4-羟基偶氮苯合成、晶体结构与异构化性能

Synthesis,Crystal Structure and Isomerization Property of 3',5'-Dibromo-3-methoxy-4-hydroxyazobenzene

以4-氨基硝基苯为原料,通过溴代、重氮化去氨基、硝基还原和重氮偶合反应合成了3＇,5＇-二溴-3-甲氧基-4-羟基偶氮苯,并通过物理掺杂方法制备了3＇,5＇-二溴-3-甲氧基-4-羟基偶氮苯-聚甲基丙烯酸甲酯（PMMA）薄膜。利用元素分析、红外光谱、质谱、核磁共振和X射线单晶衍射等技术手段对标题化合物结构进行了表征。晶体结构分析表明,标题化合物晶体属于单斜晶系,C2/c空间群,晶胞参数为a=1.6182（3）nm,b=0.81847（16）nm,c=2.1945（4）nm,β=102.819（2）°,V=2.8342（10）nm3,Z=8,Dc=1.809 g/cm3,μ=5.719 mm-1,F（000）=1504,R1=0.0366,ωR2=0.0764,化合物分子呈反式平面构型,分子间存在的氢键和苯环π-π堆积作用使得其沿b轴方向形成了一维无限链状结构。用紫外-可见光谱对标题化合物在有机溶剂、聚合物中光致反-顺异构化反应和热回复异构化反应的速率常数进行了定量测试,异构化反应的速率常数的数量级为10-1～10-2min-1。

Starting from 4-amino nitrobenzene, 3＇,5＇- dibromo-3-methoxy-4-hydroxyazobenzene （ 6 ） was synthesized via sequential reactions of dibromination, diazotization deamination, nitro-reduction and diazo coupling. Polymethyl methacrylate （PMMA） films containing azobenzene 6 were obtained by a physical doping process. The structure of the title compound was characterized by elemental analysis, FT-IR, MS （ESI） , 1H NMR, 13C NMR, MS, especially by the X-ray single crystal diffraction. The crystal crystallizes in the monoclinic space group C2/c, with a = 1. 6182（3） nm, b =0. 81847（16） nm, c =2. 1945（4） nm, β = 102.819（2） °, V=2.8342（10） nm3, Z=8, Dc =1.809 g/cm3, μ=5.719 mm-1, F（000） =1504, R1 = 0. 0366 and ωR2 = 0. 0764. The title compound exists in the trans-form. The intermolecular hydrogen bonds and π-π stacking between benzene rings contributes to one-dimensional infinite chain structure along b axis. By UV-Vis spectroscopy method, the reaction rate constants for trans-cis photoisomerization and cis-trans thermal back-isomerization are at the range of 10-1 ～ 10-2min-1.