Photoisomerization and photocyclization of 3,5-cyclohexadiene-1,2-diimine and its methyl-substituted derivatives in low-temperature argon matrices
Photoisomerization and photocyclization of 3,5-cyclohexadiene-1,2-diimine and its methyl-substituted derivatives in low-temperature argon matrices
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DOI：
10.1016/j.molstruc.2004.09.031
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发表时间：
2005-02-14
影响因子：
3.8
通讯作者：
Nakata, M
中科院分区：
文献类型：
--
作者：
Ujike, K;Akai, N;Nakata, M
在低温氩气气氛中，用紫外光（λ < 270 nm）照射1，2-二氨基苯，制备3，5-环己二烯-1，2-二亚胺。在λ> 410 nm的照射下，诱导构象从顺-顺到顺-反和反-反的变化。而410 λ> 350 nm的较短波长照射除了光环化之外还导致从顺-反到顺-顺的光异构化，得到7，8-二氮杂双环[4.2.0]辛-1，3，5-三烯。这种光环化主要发生在350 λ> 290 nm的照射下。在4-甲基-3，5-环己二烯-1，2-二亚胺的四种异构体之间和4，5-二甲基-3，5-环己二烯-1，2-二亚胺的三种异构体之间观察到由于光异构化引起的类似光谱变化，但不是由于光环化。通过含时密度泛函理论（DFT）计算得到的π-π * 和n-π * 垂直跃迁能和振子强度，阐明了光异构化反应的波长依赖性和光环化反应的甲基取代效应. (C)2004 Elsevier B. V.保留所有权利。
3,5-Cyclohexadiene-1,2-diimine was produced from 1,2-diaminobenzene in a low-temperature argon matrix by UV irradiation (lambda < 270 nm). Conformational changes from cis-cis to cis-trans and trans-trans were induced upon irradiation of lambda > 410 nm. while the shorter-wavelength irradiation of 410 > lambda > 350 nm resulted in photoisomerization from cis-trans to cis-cis in addition to photocyclization to yield 7,8-diazabicyclo[4.2.0]octa-1,3,5-triene. This photocyclization mainly occurred upon irradiation of 350 > lambda > 290 nm. Similar spectral changes due to photoisomerization among the four isomers of 4-methyl-3.5-cyclohexadiene-1.2-diimine and among the three of 4,5-dimethyl-3,5-cyclohexadiene-1,2-diimine were observed, but not due to photocyclization. The wavelength dependence for the photoisomerization and the methyl-substitution effect for the photocyclization were elucidated in terms of the pi-pi* and n-pi* vertical transition energies and oscillator strengths obtained by the time-dependent density functional theory (DFT) calculation. (C) 2004 Elsevier B.V. All rights reserved.