title: Design of hydrophobic polyoxometalate hybrid assemblies beyond surfactant encapsulation.
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 degrees 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 degrees C and 30 degrees C, respectively. Other physical properties including differential scanning calorimetry have been reported.
authors.affiliation: WestCHEM, Department of Chemistry, University of Glasgow, G12 8QQ, UK.
authors.forename: Yu-Fei
authors.initials: YF
authors.lastname: Song
authors.forename: Nicola
authors.initials: N
authors.lastname: McMillan
authors.forename: De-Liang
authors.initials: DL
authors.lastname: Long
authors.forename: Johannes
authors.initials: J
authors.lastname: Thiel
authors.forename: Yulong
authors.initials: Y
authors.lastname: Ding
authors.forename: Haisheng
authors.initials: H
authors.lastname: Chen
authors.forename: Nikolaj
authors.initials: N
authors.lastname: Gadegaard
authors.forename: Leroy
authors.initials: L
authors.lastname: Cronin
mesh_terms: D002152:Calorimetry, Differential Scanning; D002214:Capsules; D015195:Drug Design; D057927:Hydrophobic and Hydrophilic Interactions; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D008958:Models, Molecular; D008968:Molecular Conformation; D013501:Surface-Active Agents / Q000737:chemistry*; D017973:Tungsten Compounds / Q000737:chemistry*
chemical_list: D002214:Capsules; D013501:Surface-Active Agents; D017973:Tungsten Compounds