Citation: Zhang Wen-Qin, Zhang Zhi-Ming, Zheng Yan, Wang Shu-Li, Zhao Shu-Na. Crystal Structure and Photochemical Properties of r-1,c-2,t-3,t-4-1,3-bis(4-biphenyl)-2,4-di(4-pyridyl)cyclobutane[J]. Acta Physico-Chimica Sinica, 2000, 16(03): 207-213. doi: 10.3866/PKU.WHXB20000304
1,3-二联苯基-2，4-二吡啶基环丁烷的结构与光化学性质
通过反-1-(4-联苯基)-2-(4-吡啶基)乙烯(E-I)在稀硫酸中的光二聚反应合成了r-1,c-2, t-3, t-4-1, 3-双(4-联苯基)-2, 4-二(4-吡啶基)环丁烷(II). 用X射线衍射法测定了其结构. 晶体II为单斜晶系,空间群为P21/n,晶胞参数:a=1.0038(2), b=1.8995(4), c=1.4647(3)nm, β=98.82(3)°,晶胞内分子数为4. 在II的分子中,其四元环呈蝶式构象. 研究发现,在短波紫外光照射下,II容易发生光解开环反应生成其反式单体E I,随后新生成的E-I经反顺异构化反应转变为其顺式异构体(Z-I),最后反顺异构化反应达到平衡.光解II或E-I得到同样的反顺异构体混合物.
English
Crystal Structure and Photochemical Properties of r-1,c-2,t-3,t-4-1,3-bis(4-biphenyl)-2,4-di(4-pyridyl)cyclobutane
r-1,c-2, t-3, t-4-1,3-bis(4-biphenyl)-2,4-di(4-pyridyl)cyclobutane (II) was obtained in diluted sulfuric acid by photodimerization reaction. Its structure was determined by X-ray diffraction method. The crystal is monoclinic, space group is P21/n,with a=1.0038(2), b=1.8995(4), c=1.4647(3)nm, β=98.82(3)°, Z=4. The cyclobutane ring of II has puckered conformation. It was found that under short wave UV light II is easy to be photolyzed to reproduce its monomer trans-1-(4-biphenyl)-2-(4-pyridyl)ethene (E-I),and then the new formed E-I transforms to its cis-isomer(Z-I) through trans-cis isomerization. Finally, the equilibrium of isomerization establishes between E-I and Z-I. Photolysis of II or E-I will form the same isomerization mixture.
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Key words:
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Crystal strueture
- / Photodimerization
- / Trans-cis isomerization
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