By applying the concept of an inorganic structure-directing agent, uniform R-Fe 2 O 3 nanospheres of about 300 nm in diameter and well-defined nanorhombohedra of about 50-80 nm in size have been successfully synthesized using the simple inorganic sodium salt of NaAc and NaCl as the only structure-directing agent in the hydrothermal system, respectively. In comparison, only micrometer sphere-like aggregates composed of irregular nanoparticles of about 80-120 nm were obtained without the presence of any inorganic salt additives. All three nanostructures are investigated with XRD, SEM, TEM, and electrochemical tests toward lithium storage. It is found that the particle size and shape has a remarkable effect on the lithium insertion/ extraction behavior. Among the three R-Fe 2 O 3 nanostructures, nanospheres show a very high specific capacity of >600 mA h g -1 in the initial 10 cycles and >414 mA h g -1 after 60 cycles as well as good cycling performance, exhibiting great potential as anode materials in lithium-ion batteries. It benefits from the proper submicrometer size with the right surface area and the spherical shape.

SummaryMicrocystis is a cosmopolitan genus of cyanobacteria and occurs in many different forms. Large surface blooms of the cyanobacterium are well known in eutrophic lakes throughout the globe. We evaluated the role of microcystins (MCs) in promoting and maintaining bloom-forming cell aggregates at environmentally relevant MC concentrations (0.25-10 mg l

The current interest in the crystal engineering of coordination polymer frameworks not only stems from their potential applications in microelectronics, nonlinear optics, porous materials, and catalysis, but also from their intriguing variety of architectures and topologies. [1,2] Up to now, a variety of appealing interpenetrated nets, in which only internal connections are broken to separate individual nets, have been reported and reviewed by Batten and Robson. [3] In contrast, other types of entangled architectures that have recently been described-such as infinite multiple helices, [4] two-dimensional clothlike warp-and-weft sheet structures, [5] interdigitated structures in a gearlike (or tongue-and-groove) fashion, [6] and polythreaded structures with poly-pseudo-rotaxanes [7] -can, in principle, be disentangled without breaking links. Moreover, these entangled nets can lead to synthetic supramolecular arrays with potential applications in asymmetric catalysis, drug-delivery vehicles, and sensor devices.Unfortunately, these species are still rare, as evidenced in a recent review by Ciani and co-workers, [8] and therefore the exploration of new synthetic routes to this class of supramolecular architectures is one of the most challenging issues in current synthetic chemistry. On the other hand, it is wellknown that product topology can often be controlled and modulated by selecting the coordination geometry of the metal ions and the chemical nature of the organic ligands. Usually, long ligands will lead to larger voids that may result in interpenetrated structures, [3] the most outstanding example of which is 1,2-bis(4-pyridyl)ethane (bpe). With this ligand, many beautiful interpenetrated networks of ingenious design have been constructed, ranging from interpenetrating 1D ladders to 3D nets. [9] However, these results do not mean that other types of entangled structures cannot be formed in the presence of long flexible ligands. If another configurational ligand is introduced, it may be possible to gain noninterpenetrating nets by combining different precursors. In this regard, for our synthetic strategy we choose an analogy of bpe, biphenylethene-4,4'-dicarboxylic acid (bpea), whose coordination chemistry, to the best of our knowledge, has not been previously investigated. Due to the replacement of two pyridyl groups by aromatic carboxy groups, bpea will be more flexible than bpe. Therefore, to avoid interpenetration the heterocyclic aromatic ligand 1,10-phenanthroline (phen) was introduced based on the following considerations: 1) The steric hindrance at the metal center will be increased when the bulky aromatic ligand binds to the metal ion; this reduces the dimension of the net formed. Lower dimensional nets are usually less likely to interpenetrate because there are more possible ways to maximize the packing efficiency.[10] 2) Chelating bipyridyl-like ligands may provide recognition sites for p-p stacking interactions to form interesting supramolecular structures.3) The conjugated p systems containing (...

The selected-control synthesis of uniform α-Fe2O3 nanoparticles with morphologies of rhombohedra, rods, and cubes was successfully achieved in large quantities by the capping agent–cationic surfactant–CTAB-mediated hydrolysis of FeCl3. The nanoparticles were obtained when the concentration of FeCl3 ranged from 0.01 to 0.05 M at 120 °C. The growth mechanisms of α-Fe2O3 nanorhombohedra, nanorods, and nanocubes were analysed in detail, based on the topotactic transformation of the precursor β-FeOOH with different morphologies under the capping agent mediation. The concentration of FeCl3, the reaction temperature, and the concentration of CTAB are all responsible for the final crystalline morphologies of the α-Fe2O3 nanoparticles. This result may facilitate not only the exploration of controlled approaches of preparing α-Fe2O3 nanoparticles for potential technical applications but also a deeper understanding of the fundamental physical and chemical processes of hydrothermal methods. X-ray powder diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), and field-emission scanning electron microscopy (FE-SEM) were used to characterize the products.