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ExperimentalSample Preparation: A thin layer of photoresist (Shipley S1818, Shipley, MA) was spin-coated on cleaned glass substrates. A monolayer of sacrificial nanospheres was generated by drop-casting a 0.1 % solution of polystyrene colloids (150 nm; Duke Scientific, CA), which was allowed to dry overnight in a clean-zone hood to minimize contamination of the samples by dust and to stabilize the rate of evaporation. After the arrays of beads dried, metal films in various thicknesses were deposited by conventional electron-beam evaporation. The sample substrate was placed above the metal-pellet sources with a certain tilt angle (∼ 60°) with respect to the substrate surface. The substrate was rotated at a constant speed (∼ 60 revolutions per minute, rpm) during the deposition. The metal-coated colloids were released from the glass support into an aqueous suspension by lift-off with acetone. Next, the coated polymer nanospheres were collected by centrifugation (∼ 5000 rpm, 5-10 min) and suspended in toluene to dissolve the polystyrene. The sample was then centrifuged and washed three to four times in water. The nanocrescents were collected and resuspended in water or ethanol to form diluted colloids.Fluorescence Imaging and Raman Microspectroscopy: A microscopy system combining fluorescence imaging and Raman spectroscopy was used to monitor the fluorescence intensity and to acquire Ramanscattering spectra from single nanocrescents. The system consisted of a Carl Zeiss Axiovert 200 inverted microscope (Carl Zeiss, Germany) equipped with a high-speed, high-sensitivity digital camera (Cascade 512B, Roper Scientific, NJ), and a 300 mm focal length monochromator (Acton Research, MA) with a 1024 pixel × 256 pixel cooled spectrograph charge-coupled device (CCD) camera (Roper Scientific, NJ). The time-resolved fluorescence images of the nanocrescents were taken using the Cascade camera at a frame rate of 10 frames per second, a 40× objective lens (numerical aperture NA= 0.8), a fluorescein isothiocyanate (FITC) fluorescence filter set, and a 100 W mercury lamp for illumination. A 785 nm semiconductor laser was used in our experiments as the excitation source of Raman scattering, and the laser beam was focused by a 100× objective lens on the nanocrescent. The excitation power was measured by a photometer (Newport, CA) to be ∼ 1 mW. The Raman scattering light was then collected through the same optical pathway through a long-pass filter and analyzed by the spectrometer.

The introduction of cationic surfactant DODA as counterions of [Eu(H2O)2SiW11O39]5- can form a mesoscopic supramolecular assembly of (DODA)4H[Eu(H2O)2SiW11O39], which aggregates into vesicles in chloroform. This POM-based vesicle can be further transferred into three-dimensional microporous architectures under moist air. The present methodology shows that, by combining inorganic chemistry and colloidal surface chemistry, a sequential self-assembling approach based on a series of linkable preorganized building blocks allows access to the fabrication of technological applicably POM-based microsized patterns, alternated with the soft lithographic method.

In this article we provide an overview of the fabrication and properties of polyoxometalate/polymer hybrid materials. Physical blending, electrostatic adsorption, covalent bonding and supramolecular modification are the main strategies to incorporate polyoxometalates into organic or inorganic (taking silica as an example) polymer matrices. The polyoxometalate/polymer hybrid materials obtained concurrently possess the unique optical, electrical or catalytic properties of polyoxometalates and the favorable processability and stability of polymer matrices. Polyoxometalate/polymer hybrid materials may have potential applications in optics, electronics, biology, medicine and catalysis. Copyright © 2009 Society of Chemical Industry

The combination of rational design of building components and suitable utilization of driving force affords spontaneous molecular assemblies with well-defined nanostructure and morphology over multiple length scales. The serious challenges in constructing assemblies with structural advantages for the realization of functions programmed into the building components usually lie ahead since the process that occurs does not always follow the expected roadmap in the absence of external intervention. Thus, prefabricated intermediates that help in governing the target self-assemblies are developed into a type of unique building blocks. Metal oxide cluster polyanions are considered as a type of molecular nanoclusters with size scale and structural morphology similar to those of many known inorganic particles and clusters but possess distinctive characteristics. Following the understanding of these clusters in self-assembly and the rationalization of their most efficient design strategy and approach, the obtained fundamental principles can also be applied in common nanoparticle- and cluster-based systems. On the other hand, the deliberate synergy offered by organic countercations that support the self-assembly of these clusters greatly expands the opportunity for the functionalization of complex building units via control of multiple interactions. The ionic combination of the inorganic clusters with hydrophilicity and the cationic organic component with hydrophobicity leads to discrete properties of the complexes. Significantly, the core-shell structure with rigid-flexible features and amphiphilicity will pave the way for hierarchical self-assemblies of the obtained complexes, while the intrinsic characteristics of the metal oxide clusters can be modulated through external physicochemical stimuli. Within this context, over the past decade we have extensively explored the ionic combination of inorganic polyanionic clusters with cationic organic amphiphiles and devoted our efforts to establishing the general rules and structure-property relationships of the formed complexes for constructing self-assemblies at the interface, in solution, and in solid matrixes. Specific interest has been focused on the functional synergy deriving from the incompatible components in highly organized self-assemblies. In this Account, we describe the recent progress on the ionic complexation of polyoxometalate clusters with cationic amphiphiles and the construction of diverse self-assembled nanostructures. First, the fundamental structural characteristics and molecular geometries of the prepared complexes are analyzed. The construction principle and diversity of the self-assembly based on the complexes and the smart stimuli response are then discussed, subject to the adjustment of various non-covalent interactions occurring in the assemblies. Subsequently, we enumerate the functional applications of the ionic complexes assembling into organic, inorganic, and even biological matrixes. The inspiration from the construction of ionic complexation an...