State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, China.
Dalton Trans. 2012 Sep 7;41(33):10043-51. doi: 10.1039/c2dt30421j. Epub 2012 May 25.
A new kind of organic-inorganic hybrid complexes based on polyoxometalate were synthesized through symmetrically grafting two adeninyl groups onto Anderson-type MnMo(6) clusters and encapsulating the clusters by organic surfactants. The resultant complexes exhibited thermal-induced dynamic self-assembly behaviors which greatly depended on the ambient temperature and the chain length of cationic surfactants. With the encapsulation of a short surfactant tetrabutyl ammonium, the complex assembled into fibrous, rod-like, and tubular architectures respectively upon heating; while for the case of using a long surfactant dimethyldioctadecyl ammonium as counter ions, the assemblies of the complex transformed from fibers to spheres with the increased temperature. Moreover, the two types of transformations were both reversible during a cooling process. The related mechanism was investigated by combining multiple characterization methods including X-ray crystallography, XPS, FT-IR and temperature-dependent (1)H NMR, which indicated that such a thermal-induced morphological transformation resulted from a synergy effect of the variation of the multiple hydrogen bonds among the complexes and the rearrangement of the surfactants surrounding the MnMo(6) clusters. These results demonstrated a new concept that hydrogen bonds can be rationally employed as the driving force for the fabrication of polyoxometalate-based materials with smart responsive properties.
一种新型的基于多金属氧酸盐的有机-无机杂化配合物通过对称地将两个腺嘌呤基团接枝到安德森型 MnMo(6) 簇上，并通过有机表面活性剂来包裹这些簇来合成。所得配合物表现出热诱导的动态自组装行为，这主要取决于环境温度和阳离子表面活性剂的链长。在短链表面活性剂四丁基铵的包裹下，配合物在加热时分别组装成纤维状、棒状和管状结构；而对于使用长链表面活性剂二甲基十八烷基铵作为抗衡离子的情况，随着温度的升高，配合物的组装从纤维转变为球体。此外，在冷却过程中，这两种转变都是可逆的。通过结合多种表征方法，包括 X 射线晶体学、XPS、FT-IR 和温度依赖的 (1)H NMR，研究了这种热诱导形态转变的相关机制，表明这种形态转变是由于配合物之间氢键的变化以及包裹在 MnMo(6) 簇周围的表面活性剂的重排的协同效应所致。这些结果证明了一个新的概念，即氢键可以被合理地用作制造具有智能响应特性的基于多金属氧酸盐材料的驱动力。
