Guangshan Zhu

Targeted Synthesis of a Porous Aromatic Framework with High Stability and Exceptionally High Surface Area

Porous materials have been of intense scientific and technological interest because of their vital importance in many applications such as catalysis, gas separation, and gas storage. Great efforts in the past decade have led to the production of highly porous materials with large surface areas. In particular, the development of metal–organic frameworks (MOFs) has been especially rapid. Indeed, the highest surface area reported to date is claimed for a recently reported MOF material UMCM-2, which has a N2 uptake capacity of 1500 cm g at saturation, from which a Langmuir surface area of 6060 m g (Brunauer–Emmett–Teller (BET) surface area of 5200 m g) can be derived. Unfortunately, the high-surface-area porous MOFs usually suffer from low thermal and hydrothermal stabilities, which severely limit their applications, particularly in industry. These low stability issues could be resolved by replacing coordination bonds with stronger covalent bonds, as observed in covalent organic frameworks (COFs) or porous organic polymers. However, the COFs and porous organic polymers reported to date have lower surface areas compared to MOFs; the highest reported surface area for a COF is 4210 m g (BET) in COF103. Thus, further efforts are required to explore various strategies to achieve higher surface areas in COFs. Herein, we present a strategy that has enabled us to achieve, with the aid of computational design, a structure that possesses by far the highest surface area reported to date, as well as exceptional thermal and hydrothermal stabilities. We report the synthesis and properties of a porous aromatic framework PAF-1, which has a Langmuir surface area of 7100 m g. Besides its exceptional surface area, PAF-1 outperforms highly porous MOFs in thermal and hydrothermal stabilities, and demonstrates high uptake capacities for hydrogen (10.7 wt % at 77 K, 48 bar) and carbon dioxide (1300 mgg 1 at 298 K, 40 bar). Moreover, the super hydrophobicity and high surface area of PAF-1 result in unprecedented uptake capacities of benzene and toluene vapors at room temperature. It is well known that one of the most stable compounds in nature is diamond, in which each carbon atom is tetrahedrally connected to four neighboring atoms by covalent bonds (Figure 1a). Conceptually, replacement of the C C covalent bonds of diamond with rigid phenyl rings should not only retain a diamond-like structural stability but also allow sufficient exposure of the faces and edges of phenyl rings with the expectation of increasing the internal surface areas. By employing a multiscale theoretical method, which

pH-Triggered Controlled Drug Release from Mesoporous Silica Nanoparticles via Intracelluar Dissolution of ZnO Nanolids

Acid-decomposable, luminescent ZnO quantum dots (QDs) have been employed to seal the nanopores of mesoporous silica nanoparticles (MSNs) in order to inhibit premature drug (doxorubicin) release. After internalization into HeLa cells, the ZnO QD lids are rapidly dissolved in the acidic intracellular compartments, and as a result, the loaded drug is released into the cytosol from the MSNs. The ZnO QDs behave as a dual-purpose entity that not only acts as a lid but also has a synergistic antitumor effect on cancer cells. We anticipate that these nanoparticles may prove to be a significant step toward the development of a pH-sensitive drug delivery system that minimizes drug toxicity.

Ammonia Borane Confined by a Metal−Organic Framework for Chemical Hydrogen Storage: Enhancing Kinetics and Eliminating Ammonia

A system involving ammonia borane (AB) confined in a metal-organic framework (JUC-32-Y) was synthesized. The hypothesis of nanoconfinement and metallic catalysis was tested and found to be effective for enhancing the hydrogen release kinetics and preventing the formation of ammonia. The AB in JUC-32-Y started to release hydrogen at a temperature as low as 50 degrees C. The peak temperature of decomposition decreased 30 degrees C (shifted to 84 degrees C). AB inside JUC-32-Y can release 8.2 wt % hydrogen in 3 min at 95 degrees C and 8.0 and 10.2 wt % hydrogen within 10 min at 85 degrees C.

A lanthanide metal–organic framework with high thermal stability and available Lewis-acid metal sites

A lanthanide metal-organic framework, Dy(BTC)(H2O).DMF, with excellent thermal stability shows a high surface area, 655 m(2) g(-1), high hydrogen and carbon dioxide storage capability, and available Lewis-acid metal sites which could be anticipated to use in catalysis and metal-site specific chemical sensor.

From metal–organic framework (MOF) to MOF–polymer composite membrane: enhancement of low-humidity proton conductivity

A chiral two-dimensional MOF, {[Ca(D-Hpmpc)(H2O)2]·2HO0.5}n (1, D-H3pmpc = D-1-(phosphonomethyl) piperidine-3-carboxylic acid), with intrinsic proton conductivity has been synthesized and characterized. Structure analysis shows that compound 1 possesses protonated tertiary amines as proton carriers and hydrogen-bonding chains served as proton-conducting pathways. Further, MOF–polymer composite membranes have been fabricated via assembling polymer PVP with different contents of rod-like 1 submicrometer crystals. Interestingly, the proton conductivity of this composite membrane containing 50 wt% 1 is rapidly increased, compared with that of pure submicrometer crystals at 298 K and ∼53% RH. Therefore, it is feasible to introduce humidification of PVP into composite membranes to enhance low-humidity proton conductivity; and humidified PVP with adsorbed water molecules plays an important role in proton conduction indicated by the results of water physical sorption and TG/DTG analyses. This study may offer a facile strategy to prepare a variety of solid electrolyte materials with distinctive proton-conducting properties under a low humidity.

Topology-directed design of porous organic frameworks and their advanced applications

Porous organic frameworks (POFs) as an important subclass of nanoporous materials are of great interest in materials science. In recent years, the discovery and creation of POFs with excellent properties for advanced applications have attracted much attention and intensive efforts have been contributed to this field. As a result, the design of materials with multi-functionalities is an ever-pursued dream of materials scientists and engineers. In this respect, a new concept based on topology chemistry is introduced for the rational and targeted synthesis of POF materials. The present feature article provides an overview of the relationship between building blocks or starting monomers, underlying topological nets, and pre-determined structures. Several important nets are included successively from one to three dimensions. In addition, special emphasis is given to the advanced applications of designed POF materials in the current paper.

Metal-Organic Frameworks for CO2 Chemical Transformations

Carbon dioxide (CO2 ), as the primary greenhouse gas in the atmosphere, triggers a series of environmental and energy related problems in the world. Therefore, there is an urgent need to develop multiple methods to capture and convert CO2 into useful chemical products, which can significantly improve the environment and promote sustainable development. Over the past several decades, metal-organic frameworks (MOFs) have shown outstanding heterogeneous catalytic activity due in part to their high internal surface area and chemical functionalities. These properties and the ability to synthesize MOF platforms allow experiments to test structure-function relationships for transforming CO2 into useful chemicals. Herein, recent developments are highlighted for MOFs participating as catalysts for the chemical fixation and photochemical reduction of CO2 . Finally, opportunities and challenges facing MOF catalysts are discussed in this ongoing research area.

Targeted synthesis of a porous aromatic framework with a high adsorption capacity for organic molecules

Tetrakis(4-bromophenyl)methane (TBPM) as a tetrahedral unit and a diboronic acid as a linker were selected to couple the phenyl rings into a porous aromatic framework, PAF-11. PAF-11 was polymerized via a Suzuki coupling reaction. A TG analysis showed that PAF-11 is thermally stable up to 400 °C in air. PAF-11 also has a high chemical stability and cannot be dissolved or decomposed in common solvents or concentrated hydrochloric acid. A N2 sorption measurement on activated PAF-11 revealed a surface area of 952 m2 g−1 in the Langmuir model. PAF-11 also shows a considerable adsorption capacity for H2. Interestingly, PAF-11 is a highly hydrophobic material but with a high methanol uptake (654 mg g−1 at saturated vapour pressure and room temperature). PAF-11 also exhibits high adsorption abilities for small aromatic molecules such as benzene and toluene (874 and 780 mg g−1, respectively, at saturated vapour pressure and room temperature) due to its aromatic framework. This ability of PAF-11 could be very useful to eliminate harmful small aromatic molecules produced by industry.

Target synthesis of a novel porous aromatic framework and its highly selective separation of CO2/CH4

A novel porous aromatic framework based on tetra-(4-anilyl)-methane and cyanuric chloride has been designed and synthesized successfully, which possesses permanent porosity and high selectivity of CO2 towards CH4.

Strategies for the synthesis of large zeolite single crystals

Abstract The formation of large zeolite single crystals can be achieved by controlling the factors affecting the crystallization process. A review of several major strategies for the synthesis of large zeolite single crystals based on our studies is presented. Through the addition of a nucleation suppresser to the reaction mixture and optimization of the synthesis conditions, pure uniform large single crystals of LTA and FAU(X) are obtained. Large single crystals of MOR, MFI and BET are prepared using the ‘two-silicon source’ technique. In the presence of fluoride, a large number of single crystals including silicalite-I, B-, Ti-MFI, AlPO 4 -5, -11, -34. GaPO 4 and InPO are promoted. It is found that a clear homogeneous solution favors the crystallization of large single crystals of AFI. The alcoholic synthesis route has proved to be one of the most effective ways to obtain large single crystals of some zeolites and metal phosphates.