Abstract
Grafting of C‐6, C‐16 and C‐18 alkyl chains onto the hydrophilic Mn‐Anderson clusters (compounds 2–4) has been achieved. Exchange of the tetrabutyl ammonium (TBA) with dimethyldioctadecyl ammonium (DMDOA) results in the formation of new polyoxometalate (POM) assemblies (compounds 5–6), in which the POM cores are covalently functionalized by hydrophilic alkyl‐chains and enclosed by surfactant of DMDOABr. As a result, we have been able to design and synthesize POM‐containing hydrophobic materials beyond surfactant encapsulation. In solid state, scanning electron and transmission electron microscopy (SEM and TEM) studies of the TBA salts of compounds 3 and 4 show highly ordered, uniform, reproducible assemblies with unique segmented rodlike morphology. SEM and TEM studies of the DMDOA salts of compounds 5 and 6 show that they form spherical and sea urchin 3D objects in different solvent systems. In solution, the physical properties of compound 5 and 6 (combination of surfactant‐encapsulated cluster (SEC) and surface‐grafted cluster (SGC)) show a liquid‐to‐gel phase transition in pure chloroform below 0 °C, which are much lower than other reported SECs. By utilizing light scattering measurements, the nanoparticle size for compounds 5 and 6 were measured at 5 °C and 30 °C, respectively. Other physical properties including differential scanning calorimetry have been reported.