We report for the first time a novel precursor-templated conversion method for the controlled synthesis of hierarchically nanostructured magnetic hollow spheres assembled by Fe 3 O 4 or γ-Fe 2 O 3 nanosheets with a relatively high saturation magnetization. We synthesized hierarchically nanostructured hollow spheres organized by nanosheets of a layer-structured ferrous precursor by a microwave-assisted hydrothermal method in ethylene glycol (EG). Ferric chloride (FeCl 3 ‚6H 2 O) was used as the iron source, and EG acted as both a solvent and a reductant to reduce ferric salt to ferrous precursor in the presence of sodium hydroxide (NaOH) and sodium dodecyl benzene sulfonate (SDBS). The precursor was heated to prepare hierarchically nanostructured magnetic hollow spheres assembled by Fe 3 O 4 or γ-Fe 2 O 3 nanosheets, which were surface-modified with poly(ethylene glycol) (PEG). The surface-modified hierarchically nanostructured magnetic hollow spheres were explored as drug carriers. A typical anti-inflammatory drug, ibuprofen, was used for drug loading, and the release behaviors of ibuprofen in a simulated body fluid (SBF) were studied. The results indicate that these hierarchically nanostructured magnetic hollow spheres of Fe 3 O 4 or γ-Fe 2 O 3 have a high drug loading capacity and favorable release property for ibuprofen; thus, they are very promising for application in drug delivery. The samples were characterized by XRD, TEM, SEM, TG/DSC, BET, PPMS, FTIR, and UV-vis.

Iron-based MIL-88B and NH 2 -MIL-88B microcrystals with high dispersibility and uniform size were successfully synthesized by using a rapid microwave-assisted solvothermal method. By carefully controlling the reaction conditions, the microwave method provided superior quality MIL-88B crystals in high yields and excellent phase purity. Framework flexibility was observed for both MIL-88B-Fe and NH 2 -MIL-88B-Fe frameworks in various solvents, which however significantly differs between the two materials. MIL-88B-Fe shrinks reversibly by about 25% only when it is dispersed in the strongly hydrogen bonding solvents water or methanol. In contrast, NH 2 -MIL-88B-Fe shrinks up to 33% upon replacement of dimethylformamide (DMF) by any other solvent studied (benzene, chloroform, acetone, acetonitrile, methanol, water). The change in unit cell parameters (shortening of the a axis) can be seen macroscopically, although the overall integrity of the materials is maintained. We suggest that hydrogen bonding between the oxygen atoms of the MIL-88B-Fe framework and solvent molecules plays an important role in the framework shrinkage, while in the NH 2 -MIL-88B-Fe framework additional hydrogen bonds may form and thus a different breathing behavior is observed.

Crystals of MIL-88B-Fe and NH2-MIL-88B-Fe were prepared by a new rapid microwave-assisted solvothermal method. High-purity, spindle-shaped crystals of MIL-88B-Fe with a length of about 2 μm and a diameter of 1 μm and needle-shaped crystals of NH2-MIL-88B-Fe with a length of about 1.5 μm and a diameter of 300 nm were produced with uniform size and excellent crystallinity. The possibility to reduce the as-prepared frameworks and the chemical capture of carbon monoxide in these materials was studied by in situ ultrahigh vacuum Fourier-transform infrared (UHV-FTIR) spectroscopy and Mössbauer spectroscopy. CO binding occurs to unsaturated coordination sites (CUS). The release of CO from the as-prepared materials was studied by a myoglobin assay in physiological buffer. The release of CO from crystals of MIL-88B-Fe with t(1/2) = 38 min and from crystals of NH2-MIL-88B-Fe with t(1/2) = 76 min were found to be controlled by the degradation of the MIL materials under physiological conditions. These MIL-88B-Fe and NH2-MIL-88B-Fe materials show good biocompatibility and have the potential to be used in pharmacological and therapeutic applications as carriers and delivery vehicles for the gasotransmitter carbon monoxide.

We have successfully prepared for the first time hydroxyapatite (HAp) and calcium silicate (CaSiO 3 ) nanostructured porous hollow ellipsoidal capsules which are constructed by nanoplate networks using the inorganic CaCO 3 template. CaCO 3 ellipsoids are synthesized via the reaction between Ca(CH 3 COO) 2 and NaHCO 3 in water and ethylene glycol mixed solvent at room temperature and they are used as the Ca 2+ source and cores. Then a PO 4 3À or SiO 3 2À source is added to react with CaCO 3 to form a HAp or CaSiO 3 shell on the surface of CaCO 3 ellipsoids. Dilute acetic acid is used to remove remaining CaCO 3 cores. The size and shape of the HAp and CaSiO 3 hollow capsules are determined by those of the cores. The thickness of the capsule shell can be controlled by adjusting the concentration of PO 43À or SiO 3 2À source. A number of PO 4 3À sources such as dilute H 3 PO 4 , Na 3 PO 4 and Na 2 HPO 4 can be used to form HAp hollow capsules with similar morphologies. The drug loading and release behavior of HAp hollow capsules is also investigated. A typical anti-inflammatory drug, ibuprofen, is used for drug loading. The result indicates that HAp hollow capsules have a high specific surface area and high storage capacity, and favorable drug release behavior.

Layer-selective installation of functional groups at SURMOFs (surface-attached metal-organic framework multilayers) is reported. Multilayers of [Cu(ndc)(dabco)(0.5)] grown in [001] orientation on pyridine-terminated organic self-assembled monolayers on Au substrates were functionalized with amino groups by step-by-step liquid-phase epitaxy. The method allows the growth of samples exhibiting one monolayer of functional groups at the external thin-film surface. In situ quartz crystal microbalance monitoring confirmed the presence of amino groups by turning the multilayer film from a non-reactive to a reactive material for covalent binding of fluoresceinisothiocyanate, and fluorescence microscopy displays the expected luminous property.

In this paper, we describe a general method for the controlled synthesis of nanosized isoreticular metal−organic framework (IRMOF-n) crystals, which for the first time combine good monodispersity and crystallinity. Nano-IRMOF-1 and -3 crystals are produced as examples. TEM and SEM micrographs show nanocrystals with regular shape and uniform size of 200−300 nm. While powder X-ray diffraction data show a high degree of crystallinity, the BET surface area of the nano-IRMOF-1 crystals of ca. 3000 m2/g demonstrates the large internal pore volume. The nanocrystal growth mechanism under the assistance of hexadecyltrimethylammonium bromide (CTAB) as surfactant was studied by systematically changing the parameters of the preparation. The influence of each step in the preparation could be explained, and a rational synthesis protocol was thus obtained. Thereby, this work provides access to much-desired but difficult to obtain high-quality nano-MOF crystals through an optimized and rational synthesis. Moreover, the synthesis principles outlined herein should be transferable to other nanoporous materials with related growth mechanisms.

Dye modified MOF microcrystals were characterized by fluorescence microscopy (FM) and confocal laser scanning microscopy (CLSM) which visualized the position and distribution of fluorescent dyes encapsulated into MOF crystals and provided proof for selective, post-synthetic covalent modification of the external surface of MOF crystals.

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