Fuxing Sun

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.

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.

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.

In situ growth of continuous thin metal–organic framework film for capacitive humidity sensing

A large-scale continuous thin film of Cu3(BTC)2 on polished Cu slice is prepared through a method of homogenous nucleation. The film shows high phase purity and homogeneity and can be set up for capacitive humidity sensing. As a sensor, the MOF film shows good capacitive humidity sensor properties.

Synthesis of a metal–organic framework film by direct conversion technique for VOCs sensing

For the first time, a metal-organic framework Zn(3)(BTC)(2) film has been successfully synthesized on the substrate of zinc wafer by a direct conversion technique. The obtained crystal densities and inter-growth of the film have been improved via the zinc wafer conversion method. The effect of synthesis conditions on the crystallization of Zn(3)(BTC)(2) and activation of the substrate were determined to optimize the strategies for the synthesis of continuous and stable layers. The crystallization took place by converting the activated zinc layer on the substrate. The reaction between the substrate-generated zinc source and the H(3)BTC clear solution yielded the best inter-growth of crystals and formed a high-density coating. More interestingly, the fluorescence emission of the Zn(3)(BTC)(2) film was found to be highly sensitive and selective sensing to dimethylamine among different VOCs. The fluorescence intensity decreased with increasing contents of dimethylamine in ethanol solution due to weak fluorescence quenching effect. This high-quality MOF film may find promising applications in sensors, especially in VOCs sensing.

Synthesis of a porous aromatic framework for adsorbing organic pollutants application

Porous organic frameworks (POFs) have attracted considerable attention due to their high surface areas and good mechanical properties. A series of vivid characteristics in POFs, such as their plentiful phenyl rings texture, their high surface area, uniform pore size distribution and permanent porosity, make themselves suitable adsorbents to adsorb organic pollutants. To synthesize a new porous aromatic framework being composed of only phenyl rings, a monomer 1,3,5-tris(4-bromophenyl)benzene was employed. PAF-5 has been synthesized successfully using the Yamamoto-type Ullmann reaction. This material was characterized by Fourier transform infrared spectroscopy (FT-IR), 13C solid-state NMR, powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and N2 gas sorption. PAF-5 displaying high stability and high surface area exhibits excellent abilities to adsorb organic chemical pollutants at saturated vapour pressure and room temperature.

Porous aromatic frameworks with anion-templated pore apertures serving as polymeric sieves

Owing to environmental pollution and energy depletion, efficient separation of energy gases has attracted widespread attention. Low-cost and efficient adsorbents for gas separation are greatly needed. Here we report a family of quaternary pyridinium-type porous aromatic frameworks with tunable channels. After carefully choosing and adjusting the sterically hindered counter ions via a facile ion exchange approach, the pore diameters are tuned at an angstrom scale in the range of 3.4-7 Å. The designed pore sizes may bring benefits to capturing or sieving gas molecules with varied diameters to separate them efficiently by size-exclusive effects. By combining their specific separation properties, a five-component (hydrogen, nitrogen, oxygen, carbon dioxide and methane) gas mixture can be separated completely. The porous aromatic frameworks may hold promise for practical and commercial applications as polymeric sieves.

A porous metal–organic framework formed by a V-shaped ligand and Zn(II) ion with highly selective sensing for nitroaromatic explosives

A V-shaped aromatic ligand 1,3-di(4-carboxyphenyl)benzene (H2DCPB), retaining only one branch of the H6TDCPB ligand, was utilized. The assembly of this ligand with Zn(II) ions forms a two-fold interpenetrated porous MOF with pcu topology (JUC-135). The N2 adsorption isotherm of the activated sample at 77 K revealed type-I microporous characteristics. The BET and Langmuir surface areas are calculated to be 503.7 m2 g−1 and 718.9 m2 g−1, respectively. Notably, by the fluorescence technique, JUC-135 can be used to detect nitroaromatic explosives. In particular, it is one of the most efficient porous material-based sensors for TNP (KSV = 3.7 × 104 M−1). Furthermore, JUC-135 also can distinguish TNP (blue-shift) from NB, 1,3-DNB and 2,4-DNT (red-shift) by virtue of the shift direction of fluorescence spectra.

Novel lithium-loaded porous aromatic framework for efficient CO2 and H2 uptake

Novel porous aromatic frameworks, PAF-18-OH and its lithiated derivative PAF-18-OLi, have been successfully synthesized. In particular, PAF-18-OLi displays significant enhancement of H2 and CO2 adsorption capacity, especially for CO2 uptake (14.4 wt%). More valuably, the stable PAF-18-OLi material exhibits high CO2/N2 selectivity, as high as 129 in the case of CO2 capture from simulated post-combustion flue gas mixtures (85% N2 and 15% CO2). Furthermore, the PAF-18-OLi has shown improved H2 storage capacity after lithiation.