Misawa Toshiyuki, Kobayashi Jun, Kiyota Yoshiki, Watanabe Masayuki, Ono Seiji, Okamura Yosuke, Koguchi Shinichi, Higuchi Masashi, Nagase Yu, Ito Takeru
Department of Chemistry, School of Science, Tokai University, 4-1-1 Kitakaname, Hiratsuka 259-1292, Japan.
Department of Applied Chemistry, School of Engineering, Tokai University, 4-1-1 Kitakaname, Hiratsuka 259-1292, Japan.
Materials (Basel). 2019 Jul 16;12(14):2283. doi: 10.3390/ma12142283.
Ionic liquids are an important component for constructing functional materials, and polyxometalate cluster anion is a promising partner for building inorganic-organic hybrid materials comprising ionic liquids. In such hybrid materials, the precise control of the molecular arrangement in the bulk structures is crucial for the emergence of characteristic functions, which can be realized by introducing an amphiphilic moiety into the ionic liquids. Here, an amphiphilic polymerizable imidazolium ionic liquid with a methacryloyl group was firstly hybridized with polyoxometalate anions of octamolybdate ([MoO], Mo) and silicotungstate ([SiWO], SiW) to obtain inorganic-organic hybrid crystals. The polymerizable ionic liquid with a octyl chain (denoted as MAImC) resulted in the formation of anisotropic molecular arrangements in the bulk crystal structure, which was compared with the hybrid crystals composed from the polymerizable ionic liquid without a long alkyl chain (denoted as MAIm). Rather densely packed isotropic molecular arrangements were observed in the hybrid crystals of MAIm-Mo and MAIm-SiW due to the lack of the amphiphilic moiety. On the other hand, using the amphiphilic MAImC cation gave rise to a honeycomb-like structure with the Mo anion and a layered structure with the SiW anion, respectively.
离子液体是构建功能材料的重要组成部分，多金属氧酸盐簇阴离子是构建包含离子液体的无机-有机杂化材料的理想伙伴。在这类杂化材料中，精确控制整体结构中的分子排列对于特性功能的出现至关重要，这可以通过在离子液体中引入两亲性部分来实现。在此，首先将一种带有甲基丙烯酰基的两亲性可聚合咪唑鎓离子液体与八钼酸盐（[MoO]，Mo）和硅钨酸盐（[SiWO]，SiW）的多金属氧酸盐阴离子进行杂化，以获得无机-有机杂化晶体。带有辛基链的可聚合离子液体（记为MAImC）导致在整体晶体结构中形成各向异性的分子排列，这与由没有长烷基链的可聚合离子液体（记为MAIm）组成的杂化晶体进行了比较。由于缺乏两亲性部分，在MAIm-Mo和MAIm-SiW的杂化晶体中观察到相当致密堆积的各向同性分子排列。另一方面，使用两亲性的MAImC阳离子分别产生了与Mo阴离子形成的蜂窝状结构和与SiW阴离子形成的层状结构。
