Reversible Transformation between Azo and Azonium Bond Other than Photoisomerization of Azo Bond in Main-Chain Polyazobenzenes
Reversible Transformation between Azo and Azonium Bond Other than Photoisomerization of Azo Bond in Main-Chain Polyazobenzenes
复制标题
主链聚偶氮苯中偶氮键和氮键之间的可逆转化（除了偶氮键的光致异构化）
DOI：
10.1021/acs.jpclett.1c00750
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发表时间：
2021
影响因子：
5.7
通讯作者：
Huang Mu-Hua
中科院分区：
文献类型：
--
作者：
Younis Muhammad;Long Jonathan;Peng Shan-Qing;Wang Xiao-Song;Chai Chunpeng;Bogliotti Nicolas;Huang Mu-Hua
虽然侧链多偶氮苯已被广泛研究，但主链多偶氮苯(简称MCPAB)由于合成困难和偶氮键的光致异构化所带来的挑战而鲜有报道。因此，除了MCPAB中偶氮键的光异构化外，还需要开发新的机理来扩大其应用范围。在这项工作中，我们通过快速NaBH4介导的还原偶联聚合，在N-取代双(4-硝基苯基)胺上合成了一系列新的N-连接的MCPAB。通过长、短接触时间的CPMAS13C核磁共振、交叉极化反转(CPPI)、交叉极化非四元抑制(CPNQS)等固体核磁共振实验对MCPAB的结构进行了表征。MCPAB中的偶氮键被酸化后形成的偶氮离子具有显著的从红色到绿色的显著颜色变化，被发现在酸蒸气传感方面是很有前途的。MCPAB的氮离子在碱性蒸气中由绿色变为红色，适合于碱性蒸气传感。
Although side-chain polyazobenzenes have been extensively studied, main-chain polyazobenzenes (abbreviated MCPABs) are rarely reported due to the challenges associated with difficulty in synthetic chemistry and photoisomerization of azo bonds in MCPABs. Thus, it is highly demanded to develop new mechanisms other than photoisomerization of azo bonds in MCPABs to extend their applications. In this work, we created a new series of N-linked MCPABs via fast NaBH4-mediated reductive coupling polymerization on N-substituted bis(4-nitrophenyl)amines. The structure of MCPABs has been characterized by comprehensive solid-state NMR experiments such as CPMAS13C NMR with long and short contact times, cross-polarization polarization-inversion (CPPI), and cross-polarization nonquaternary suppressed (CPNQS). The azo bonds in MCPABs were found to be promising for acid vapor sensing, being acidified to form azonium ion with significant color change from red to green. And the azonium of MCPABs turned from green to red when exposed to base vapor, thus suitable for base vapor sensing.