Preparation and Self-Assembly of a 2:1 Polyoxometalate-Fullerene C60 Shape Amphiphile

Graphical A unique amphiphile was prepared whereby two Dawson polyoxometalates were covalently connected to one fullerene C 60 sphere. The amphiphile shows tunable aggregation behaviour in single and binary solvent mixtures controlled by collective effects of π–π interaction, electrostatic interaction and solvophobic effect. Two-dimensional plates, solid spheres and vesicles have been observed, which represent a new class of multifunctional materials. An organic-inorganic hybrid ( 5 ) is synthesized where two Dawson polyoxometalate (POM) moieties are linked to one fullerene C 60 unit. In a POM-friendly solvent such as DMSO, DMF and CH 3 CN, 5 forms small vesicles below 100 nm at a concentration of 37.3 mg mL –1 . When the concentration decreases to 9.0 mg mL –1 , detection of aggregates becomes difficult. However, supramolecular structures with diverse morphologies can be induced upon the addition of H 2 O or toluene. In DMSO/H 2 O and DMF/H 2 O systems, plates form, which break to debris and small vesicles at high volume percentage of H 2 O. In CH 3 CN/H 2 O mixtures, solid spheres form, which fail to further evolve into other self-assembled structures. In DMSO-based binary mixtures, the type of poor solvent has a big influence on the aggregation behavior of 5 , and replacing H 2 O with toluene transfers the aggregates from plates to multilamellar and multicellular vesicles. In contrast, in CH 3 CN-based systems, the influence of the type of poor solvent is quite limited. Although the morphologies of the aggregates change a lot, their magnetic properties remain unchanged as confirmed by electron spin-resonance measurements.