Synthesis of Bridged Indigos and Their Thermoisomerization and Photoisomerization Behaviors
Synthesis of Bridged Indigos and Their Thermoisomerization and Photoisomerization Behaviors
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DOI：
10.1021/acs.joc.1c01726
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发表时间：
2021-12-17
影响因子：
3.6
通讯作者：
Tsubaki, Kazunori
中科院分区：
文献类型：
--
作者：
Kanda, Junya;Egami, Naoki;Tsubaki, Kazunori
通过用碳链桥接靛蓝结构中的两个氮原子来合成桥接靛蓝，并仔细检查它们的性质。这些桥联靛蓝具有固有的平面手性，并使用手性高效液相色谱法分离对映体。当手性桥联靛蓝进行热异构化和光异构化时，根本观察不到相应的（Z）-靛蓝，并且观察到外消旋化。这种现象是由于靛蓝骨架双键的1.5键级导致的低反转活化能以及（E）-靛蓝和（Z）-靛蓝基态之间的大能量差造成的。
Bridged indigos were synthesized by bridging the two nitrogen atoms in the indigo structure with a carbon chain, and their properties were carefully examined. These bridged indigos have intrinsic planar chirality, and the enantiomers were separated using chiral high-performance liquid chromatography. When the chiral bridged indigos were subjected to thermo- and photoisomerization, the corresponding (Z)-indigo was not observed at all, and racemization was observed. This phenomenon is caused by the low activation energy of inversion due to the 1.5 bond order of the double bond of the indigo skeleton and the large energy difference between the ground states of (E)-indigo and (Z)-indigo.