杂芳基乙烯光化学反应的研究——Ⅱ.r-1,c-2,t-3,t-4-1,3-二(4-甲基苯基)-2,4-二(4-吡啶基)环丁烷的结构及光解反应

Studies on the Photochemical Reaction of Heteroarylethenes II .Structure and Chemical Properties of r-1,c-2,t-3, t-4- 1,3 - Bis (4-methylphenyl)-2,4-bis (4-pyridyl) cyclobutane

通过反－１－（４－甲基苯基）－２－（４－吡啶基）乙烯（Ｅ－ＭＥＰ）在稀盐酸中的光二聚反应得到了接近定量的标题化合物（ＤＭＤＰＣ），用元素分析，ＩＲ，ＵＶ，＾在Ｈ，ＮＭＲ和ＭＳ表征了其结构，并用Ｘ射线衍射法测定了ＤＭＤＰＣ的晶体结构，ＤＭＤＰＣ属单斜晶系，空间群为Ｐ２１／ｃ，晶胞参数ａ＝１．１３７６（６），ｂ＝１．７３７９（８），ｃ＝１．１５９０（５）ｎｍ，β＝１０６．１６（４）°，Ｚ＝４。

Crystal structure of r - 1,c - 2,t - 3,t - 4 - 1,3 - bis(4 - methylphenyl) - 2,4 - bis (4-pyridyl)cyclobutane(DMDPC) was determined by X-ray diffraction method. The crystal ismonoclinic, space group is P21/c, with a = 1.1376(6), b = 1.7379(8), c = 1.1590(5)nm, β = 106.16(4)°, Z = 4. The cyclobutane ring has a puckered conformation because of repelling of the pyridine ring and benzene ring at the same side of the four - membered ring. It was found that the cyclobutane ring of DMDPC would be opened when irradiated under short wave UV light, trans - 1 - (4 - methylphenyl) - 2 - (4 - Pyridyl)ethene(E - MEP) was reproduced, then some of E - MEP was changed to its cis isomer. The ratio of trans to cis isomer was controlled by the wave length of irradiating light.