3D nanostructures have attracted much attention because of their unique properties and potential applications. [1][2][3][4][5][6][7][8][9][10][11][12][13] The simplest synthetic route to 3D nanostructures is probably selfassembly, in which ordered aggregates are formed in a spontaneous process.[2] However, it is still a big challenge to develop simple and reliable synthetic methods for hierarchically selfassembled architectures with designed chemical components and controlled morphologies, which strongly affect the properties of nanomaterials. Iron oxides have been extensively studied in diverse fields including catalysis, [14][15][16] environment protection, [17][18][19][20][21][22][23] sensors, [24] magnetic storage media, [25] and clinical diagnosis and treatment. [26] Various iron oxide structures, such as nanocrystals, [27][28][29] particles, [30,31] cubes, [32] spindles, [33] rods, [34,35] wires, [36] tubes, [37] and flakes, [38] have been successfully fabricated by a variety of methods. However, the self-assembly of these low-dimensional building blocks into complex 3D ordered nanostructures is still considerably more difficult. In order to further understand the mechanism of self-organization and expand the applications of iron oxide nanomaterials, self-assembled iron oxide 3D nanostructures need to be explored in more detail. Herein, we report the synthesis of novel 3D flowerlike iron oxide nanostructures by an ethylene glycol (EG)-mediated self-assembly process. Such a method has been adopted previously for the preparation of V 2 O 5 hollow microspheres, [7] SnO 2 nanowires, [39,40] and cobalt alkoxide disk-shaped particles.[41] However, in these previous studies, expensive metal organic compounds including acetates, oxalates, or acetylacetonates were used as metal-ion sources; in this study we used ferric chloride, an inexpensive and nontoxic reagent, as our iron source. By calcination at an elevated temperature, the assynthesized iron oxide precursor was transformed into iron oxide. The phase of the final product could easily be controlled to be either a-Fe 2 O 3 , c-Fe 2 O 3 , or Fe 3 O 4 , three of the most common iron oxides, simply by altering the calcination conditions. All of the products maintained their original flowerlike morphology. The reaction mechanism leading to the iron oxide precursor and the self-assembly process are discussed. As an example of potential applications, the as-obtained iron oxide nanomaterials were used as adsorbent in waste-water treatment, and showed an excellent ability to remove various water pollutants. In a typical procedure, ferric chloride (FeCl 3 ·6 H 2 O), urea, and tetrabutylammonium bromide (TBAB) were dissolved in EG. The solution was refluxed at ca. 195°C for 30 min. After cooling, the as-synthesized iron oxide precursor was collected as a green precipitate by four centrifugation and ethanolwashing cycles. The morphology of the precursor was studied by scanning electron microscopy (SEM). Figure 1a shows the SEM image of a typical sample composed of many un...

Hierarchically structured metal oxides have two or more levels of structure. Their nanometer‐sized building blocks provide a high surface area, a high surface‐to‐bulk ratio, and surface functional groups that can interact with, e.g., heavy metal ions. Their overall micrometer‐sized structure provides desirable mechanical properties, such as robustness, facile species transportation, easy recovery, and regeneration. In combination these features are suitable for the removal of heavy metal ions from water. Several general synthesis routes for the fabrication of metal oxides with various morphologies and hierarchical structures are discussed including soft and hard template‐assisted routes. These routes are general, reliable, and environmentally friendly methods to prepare transition and rare earth metal oxides, including cobalt oxide, iron oxide, and ceria. As‐prepared hierarchically structured metal oxides show excellent adsorption capacities for AsV and CrVI ions in water.

Ceria hollow nanospheres composed of CeO2 nanocrystals were synthesized via a template-free and microwave-assisted aqueous hydrothermal method. This is a low-cost and environmentally benign method. The chemicals used are all environmentally benign materials (cerium nitrate, urea, and water). An Ostwald ripening mechanism coupled with a self-templated, self-assembly process, in which amorphous solid spheres are converted to crystalline nanocrystals and the latter self-assemble into hollow structures, was proposed for the formation of the hollow structures. The products were characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, high-resolution TEM, energy-dispersive X-ray analysis, X-ray photoelectron spectroscopy, and N2 adsorption−desorption methods. These ceria hollow nanospheres show an excellent adsorption capacity for heavy metal ions, for example, 22.4 mg g−1 for As(V) and 15.4 mg g−1 for Cr(VI). These values are significantly higher than reported data from other ceria nanostructures. These ceria hollow nanospheres are also excellent supports for gold nanoparticles, forming a Au/CeO2 composite catalyst. In CO oxidation, a 100% CO conversion was achieved at room temperature.

A novel in-situ route was developed to load well-dispersed palladium (Pd) nanoparticles on the surface of hydroxyl-group-rich titania precursor. Pd nanoparticles are formed by in-situ reduction of Pd(II) by Sn(II); the latter is linked to the surface of TiO 2 precursors through inorganic grafting. The initial Pd nanoparticles then serve as seed for subsequent particle growth and allow us to systematically control the amount and size of the Pd nanoparticles by varying the amount of added PdCl 2 . The Pd nanoparticles, with no protection from ligands, are well-dispersed on the TiO 2 precursor surface without aggregation even at a high Pd loading of 22.5 wt %. The method is also extended to introduce other noble metal nanoparticles including Au, Ag, Pt, and their bimetallic nanoparticles onto the TiO 2 precursor surface. The as-obtained TiO 2 precursor-Pd composite is a promising catalyst in nanocatalysis. As an example, the TiO 2 precursor-Pd shows high catalytic activity for Suzuki cross-coupling reaction and can be recycled multiple times without loss of activity.

Zinc binding groups (ZBGs) play a crucial role in targeting histone deacetylase inhibitors (HDACIs) to the active site of histone deacetylases (HDACs), thus determining the potency of HDACIs. Due to the high affinity to the zinc ion, hydroxamic acid is the most commonly used ZBG in the structure of HDACs. An alternative ZBG is benzamide group, which features excellent inhibitory selectivity for class I HDACs. Various ZBGs have been designed and tested to improve the activity and selectivity of HDACIs, and to overcome the pharmacokinetic limitations of current HDACIs. Herein, different kinds of ZBGs are reviewed and their features have been discussed for further design of HDACIs.

A sandwichlike magnesium silicate/reduced graphene oxide nanocomposite (MgSi/RGO) with high adsorption efficiency of organic dye and lead ion was synthesized by a hydrothermal approach. MgSi nanopetals were formed in situ on both sides of RGO sheets. The nanocomposite with good dispersion of nanopetals exhibits a high specific surface area of 450 m(2)/g and a good mass transportation property. Compared to MgSi and RGO, the mechanical stability and adsorption capacity of the nanocomposite is significantly improved due to the synergistic effect. The maximum adsorption capacities for methylene blue and lead ion are 433 and 416 mg/g, respectively.

An intelligent pH-responsive carrier and release system based on DNA nanoswitch-controlled organization of gold nanoparticles (AuNPs) attached to mesoporous silica (MS) has been designed and demonstrated.

Single-crystal submicrometer rods and tubes of C 60 with highly uniform size and shape were produced from a solvent-induced and surfactant assisted self-assembly technique. The length and length-to-width ratio of both rods and tubes were tunable by controlling the concentration of C 60 in the stock solution. The transformation from rod to tube was achieved by simply varying the volume ratio of two solvents. Fouriertransform infrared and Raman spectroscopy, X-ray diffraction and high-resolution transmission electron microscopy revealed the detailed structures of the rods and tubes. We proposed a concentration profile based growth model to describe the self-assembly process of C 60 subunits. This study may contribute to better understanding of chemistry of fullerenes in solutions and extend the surfactant-assisted self-organization of inorganic system to fullerene system.