Cyclodextrin-/photoisomerization-modulated assembly and disassembly of an azobenzene-grafted polyoxometalate cluster
Cyclodextrin-/photoisomerization-modulated assembly and disassembly of an azobenzene-grafted polyoxometalate cluster
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环糊精/光异构化调节偶氮苯接枝多金属氧酸盐簇的组装和拆卸
DOI：
10.1039/c8dt05146a
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发表时间：
2019
影响因子：
4
通讯作者：
Wu Lixin
中科院分区：
文献类型：
--
作者：
Li Hongbo;Jiang Fengrui;Zhang Guohua;Li Bao;Wu Lixin
本文制备了一种通过Sn离子桥连偶氮苯基团的单缺位Keggin型聚氧乙烯酸盐（POM）[SiW 11 O39]8-，并通过元素分析、NMR、TGA和IR等技术对所形成的有机-无机杂化簇合物进行了表征。在TEM图像中观察到水介质中的混合簇组装体的囊泡结构，并且在α-/β-，γ-环糊精（α-/β-，γ-CD）存在下其解离;这种解离由主客体相互作用驱动。在365 nm光照射下，单分散包合物进一步重新组装成较小的胶束，并且这种转变可以通过交替照射450 nm光来可逆控制。此外，在POM-Azo/β-CD体系的情况下，通过加入竞争性客体分子实现了从单分散状态到囊泡状态的重组。因此，可逆的主-客体相互作用结合偶氮苯基团的可逆光异构化提供了多种方式来调节POM杂化物的组装和拆卸以及不同组装之间的变化。本研究启发了这类杂化多金属氧酸盐在强化催化反应和循环利用中的潜在用途。
Herein, a mono-lacunary Keggin-type polyoxometalate (POM), [SiW11O39]8−, grafted with an azobenzene group through Sn ion bridging was prepared, and the formed organic–inorganic hybrid cluster was characterized via elemental analysis, NMR, TGA, and IR techniques. A vesicular structure of the hybrid cluster assembly in aqueous media was observed in the TEM image, and it dissociated in the presence of α-/β-, γ-cyclodextrins (α-/β-, γ-CDs); this dissociation was driven by the host–guest interactions. The monodispersed inclusion complex further reassembled into smaller micelles under irradiation with 365 nm light, and this transformation was reversibly controlled by alternating the irradiation with 450 nm light. Moreover, in the case of the POM-Azo/β-CD system, reassembly from the monodispersed state to the vesicular state was achieved by the addition of a competitive guest molecule. Thus, the reversible host–guest interactions combining reversible photoisomerization of the azobenzene group provided multiple ways to modulate the assembly and disassembly of the POM hybrid as well as the changes between different assemblies. The present study inspires the potential use of these kind of hybrid POMs in enhanced catalytic reactions and recycling.