New photoswitching unit for magnetic interaction: diarylethene with 2,5-bis(arylethynyl)-3-thienyl group.
New photoswitching unit for magnetic interaction: diarylethene with 2,5-bis(arylethynyl)-3-thienyl group.
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DOI：
10.1021/ja053200p
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发表时间：
2005-09
影响因子：
15
通讯作者：
N. Tanifuji;M. Irie;K. Matsuda
中科院分区：
文献类型：
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作者：
N. Tanifuji;M. Irie;K. Matsuda
利用带有2，5-二（芳基乙炔基）-4-甲基-3-噻吩基侧基的二芳基乙烯证明了分子内磁相互作用的光开关。在2，5-双（芳基乙炔基）-4-甲基-3-噻吩基的每一端放置两个氮氧自由基。在芳基乙炔基部分中使用三种芳基，2，5-亚噻吩基、对亚苯基和间亚苯基。二芳基乙烯光开关单元在二芳基乙烯的一侧上具有延伸的π-共辄链。光致变色反应性取决于芳基乙炔基。含间苯撑的二芳基乙烯表现出高效的光致变色反应性。随着光致变色反应的沿着，二芳基乙烯表现出源于两个未成对电子之间的磁相互作用的变化的ESR谱的光开关。开环异构体比光生闭环异构体表现出更强的交换相互作用。由于噻吩环2位的杂合轨道从sp（2）改变为sp（3），两个自由基通过π共轭链之间的磁相互作用被光环化改变。
Photoswitching of the intramolecular magnetic interaction was demonstrated using diarylethenes with 2,5-bis(arylethynyl)-4-methyl-3-thienyl side group. Two nitroxide radicals were placed at each end of the 2,5-bis(arylethynyl)-4-methyl-3-thienyl group. Three kinds of aryl groups, 2,5-thienylene, p-phenylene, and m-phenylene groups, were used in the arylethynyl moiety. The diarylethene photoswitching units have an extended pi-conjugated chain on one side of the diarylethene. The photochromic reactivity was dependent on the arylethynyl group. Diarylethenes with m-phenylene group showed an efficient photochromic reactivity. Along with the photochromic reaction the diarylethenes showed photoswitching of an ESR spectrum originating from the change in the magnetic interaction between two unpaired electrons. The open-ring isomer showed stronger exchange interaction than the photogenerated closed-ring isomer. The magnetic interaction between two radicals via the pi-conjugated chain was altered by photocyclization due to the change of the hybrid orbital at the 2-position of the thiophene ring from sp(2) to sp(3).