Abstract
The self-assembly of organic amphiphilic species into various aggregates such as spherical or elongated micelles, cylinders up to the formation of lyotropic hexagonal or lamellar phases results from cooperative processes orchestrated by hydrophobic effect, while those involving ionic inorganic polynuclear entities and non-ionic organic components are still intriguing. Herein, we report on the supramolecular behavior of giant toroidal molybdenum blue-type polyoxometalate (POM), namely the {Mo$_{154}$} species in the presence of n-octyl-$\beta$-glucoside (C8G1), widely used as surfactant in biochemistry. Structural investigations were carried out using a set of complementary multiscale methods including single-crystal X-ray diffraction analysis supported by molecular modelling, small-angle X-ray scattering (SAXS), and cryo-TEM observations. In addition, liquid NMR, viscosimetry, surface tension measurement, and isothermal titration calorimetry (ITC) provided further information to decipher the complex aggregation pathway. Elucidation of the assembly process reveals a rich scenario where the presence of the large {Mo$_{154}$} anion disrupts the selfassembly of the C8G1, well-known to produce micelles, and induces striking successive phase transitions from fluid-to-gel and from gel-to-fluid. Herein, intimate organic-inorganic primary interactions arising from the super-chaotropic nature of the {Mo154} lead to versatile nanoscopic hybrid C8G1-{Mo$_{154}$} aggregates including crystalline discrete assemblies, smectic lamellar liquid crystals, and large uni-or multilamellar vesicles where the large torus {Mo$_{154}$} type POM acts a trans-membrane component.