Self-assembly, aggregates morphology and ionic liquid crystal of polyoxometalate-based hybrid molecule: From vesicles to layered structure

Polyoxometalate anions [SBA(12)O(40)]4 were encapsulated by four 1, 3-dioctadecylimidazolium cations (labeled as L+) driven by electrostatic interaction to obtain hybrid molecule L-4[SiW12O40]. The composition and ingredients of L-4[SiW12O40] were confirmed by infrared spectroscopy (IR) and elemental analysis. In mixedsolvent (chloroform/methanol volume of 4:1), the self-assembled aggregates of L-4[SiW12O40] appear at multilamllar vesicles under optical microscopy and the micron-size bulky flower-like aggregates in scanning electron microscopy (SEM). However, Transmission electron microscopy (TEM) images and small-angle X-ray diffraction (XRD) of L-4[SiW12O40] demonstrate that spherical aggregations in mixed-solvent are densely packed by flakes, which can self-assembly into ordered one dimension layered structure. In addition, L-4[SiW12O40] shows typical thermotropic liquid crystal behavior similar to imidazole cations. The ordered self-assembly hybrid molecule materials based on organic-polyoxometalate ionic liquids would be exciting branch of nanostructure functional materials. (C) 2017 Elsevier B.V. All rights reserved.