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合成了 1 ,n-双 [4 -[2 -[2 -( 5-甲基苯并唑基 ) ]乙烯基 ]苯氧基 ]烷烃 ( a:n=3 ; b:n=4 ; c:n=6)和 2 ,2 -双 [4 -[2 -[2 -( 5-甲基苯并唑基 ) ]乙烯基 ]苯氧基 ]乙醚 ( d) 4个新化合物 .用元素分析、红外、紫外、核磁共振谱和质谱表征了其结构 .用紫外吸收光谱跟踪研究了 a_ d在紫外灯照射下的变化 ,发现上述化合物在高压汞灯照射下可同时发生反顺异构化和 [2 +2 ]分子内光二聚两种反应 ,反顺异构化反应迅速可逆 ,而光二聚反应进行缓慢且不可逆 .增加链长有助于提高分子内光二聚反应的速率 .分子内光二聚反应不受空气中氧的影响的事实表明其是经激发单线态历程进行的 .还发现分子内光二聚体在短波紫外光照射下容易进行逆 [2 +2 ]光解开环反应 .上述化合物分子内光二聚和光解开环反应可以反复进行多次 ,表明该类化合物具有较高的光稳定性
(A: n = 3; b: n = 4; c: 1, n -bis [4- [2- [2- (n = 6), and 4 new compounds were synthesized using the same procedure as in the synthesis of 2 Their structures were characterized by IR, UV, 1H-NMR and MS spectra. The changes of a_d after UV irradiation were observed by UV absorption spectroscopy. The results showed that the above compounds could be simultaneously isomerised by high pressure mercury lamp And [2 +2] intramolecular photodimerization two reactions, anti-cis isomerization reaction rapidly reversible, while the photodimerization reaction is slow and irreversible. Increasing the chain length can help improve the rate of intramolecular photodimerization reaction. The fact that the poly-reaction is unaffected by the oxygen in the air shows that it is excited by the singlet-state course and it has also been found that intramolecular photodimers are easily subjected to reverse [2 + 2] photolytic ring-opening reactions under short-wave ultraviolet light irradiation. Endo-dimerization and photodissociation of the ring-opening reaction can be repeated several times, indicating that the compounds have higher photostability