Modelling a Linker Mix‐and‐Match Approach for Controlling the Optical Excitation Gaps and Band Alignment of Zeolitic Imidazolate Frameworks

Tuning the electronic structure of metal–organic frameworks is the key to extending their functionality to the photocatalytic conversion of absorbed gases. Herein we discuss how the band edge positions in zeolitic imidazolate frameworks (ZIFs) can be tuned by mixing different imidazole‐based linkers within the same structure. We present the band alignment for a number of known and hypothetical Zn‐based ZIFs with respect to the vacuum level. Structures with a single type of linker exhibit relatively wide band gaps; however, by mixing linkers of a low‐lying conduction edge with linkers of a high‐lying valence edge, we can predict materials with ideal band positions for visible‐light water splitting and CO₂ reduction photocatalysis. By introducing copper in the tetrahedral position of the mixed‐linker ZIFs, it would be possible to increase both photo‐absorption and the electron–hole recombination times.     

Using a Multi‐Shelled Hollow Metal–Organic Framework as a Host to Switch the Guest‐to‐Host and Guest‐to‐Guest Interactions

A bio‐inspired design of using metal–organic framework (MOF) microcrystals with well‐defined multi‐shelled hollow structures was used as a matrix to host multiple guests including molecules and nanoparticles at separated locations to form a hierarchical material, mimicking biological structures. The interactions such as energy transfer (ET) between different guests are regulated by precisely fixing them in the MOF shells or encapsulating them in the cavities between the MOF shells. The proof‐of‐concept design is demonstrated by hosting chromophore molecules including rhodamine 6G (R6G) and 7‐amino‐4‐(trifluoromethyl)coumarin (C‐151), as well as metal nanoparticles (Pd NPs) into the multi‐shelled hollow zeolitic imidazolate framework‐8 (ZIF‐8). We could selectively establish or diminish the guest‐to‐framework and guest‐to‐guest ET. This work provides a platform to construct complex multifunctional materials, especially those need precise separation control of multi‐components.     

In Situ Generation and Stabilization of Accessible Cu/Cu2O Heterojunctions inside Organic Frameworks for Highly Efficient Catalysis

Heterostructural metal/metal oxides are the very promising substituents of noble‐metal catalysts; however, generation and further stabilization of accessible metal/metal oxide heterojunctions are very difficult. A strategy to encapsulate and stabilize Cu/Cu₂O nanojunctions in porous organic frameworks in situ is developed by tuning the acrylate contents in copper‐based metal–organic frameworks (Cu‐MOFs) and the pyrolytic conditions. The acrylate groups play important roles on improving the polymerization degree of organic frameworks and generating and stabilizing highly dispersed and accessible Cu/Cu₂O heteronanojunctions. As a result, pyrolysis of the MOF ZJU‐199, consisting of three acrylates per ligand, generates abundant heterostructural Cu/Cu₂O discrete domains inside porous organic matrices at 350 °C, demonstrating excellent catalytic properties in liquid‐phase hydrogenation of furfural into furfuryl alcohol, which are much superior to the non‐noble metal‐based catalysts.     

Fabrication of Thermo‐Responsive Hybrid Hydrogels by In‐Situ Mineralization and Self‐Assembly of Microgel Particles

Summary: An in‐situ mineralization process in the presence of thermo‐responsive microgels leads to the formation of well‐defined hybrid materials. Experimental data suggest that control of the mineralization process in the presence of the microgels offers the possibility to obtain sub‐micrometer‐sized hybrid particles or macroscopic hybrid hydrogels. The rapid formation of CaCO₃ crystals in the microgel structure favors the preparation of the hybrid particles wherein inorganic crystals cover the shell layer of the microgel. The slow formation of CaCO₃ crystals leads to the simultaneous self‐assembly of the microgel particles on the bottom of the reaction vessel, and the formation of a physical network. It has been demonstrated that hybrid hydrogel materials with different calcium carbonate contents and temperature‐dependent swelling‐deswelling properties can be prepared.

Formation of a hybrid hydrogel by the vapor diffusion method.     

In Situ Formation of a MoS2‐Based Inorganic–Organic Nanocomposite by Directed Thermal Decomposition

Nanocomposites based on molybdenum disulfide (MoS₂) and different carbon modifications are intensively investigated in several areas of applications due to their intriguing optical and electrical properties. Addition of a third element may enhance the functionality and application areas of such nanocomposites. Herein, we present a facile synthetic approach based on directed thermal decomposition of (Ph₄P)₂MoS₄ generating MoS₂ nanocomposites containing carbon and phosphorous. Decomposition at 250 °C yields a composite material with significantly enlarged MoS₂ interlayer distances caused by in situ formation of Ph₃PS bonded to the MoS₂ slabs through Mo?S bonds and (Ph₄P)₂S molecules in the van der Waals gap, as was evidenced by ³¹P solid‐state NMR spectroscopy. Visible‐light‐driven hydrogen generation demonstrates a high catalytic performance of the materials.     

One‐pot synthesis of magnetic zeolitic imidazolate framework/grapheme oxide composites for the extraction of neonicotinoid insecticides from environmental water samples

Magnetic zeolitic imidazolate framework 67/graphene oxide composites were synthesized by one‐pot method at room temperature for the first time. Electrostatic interactions between positively charged metal ions and both negatively charged graphene oxide and Fe₃O₄ nanoparticles were expected to chemically stabilize magnetic composites to generate homogeneous magnetic products. The additional amount of graphene oxide and stirring time of graphene oxide, Co²⁺, and Fe₃O₄ solution were investigated. The zeolitic imidazolate framework 67 and Fe₃O₄ nanoparticles were uniformly attached on the surface of graphene oxide. The composites were applied to magnetic solid‐phase extraction of five neonicotinoid insecticides in environmental water samples. The main experimental parameters such as amount of added magnetic composites, extraction pH, ionic strength, and desorption solvent were optimized to increase the capacity of adsorbing neonicotinoid insecticides. The results show limits of detection at signal‐to‐noise ratio of 3 were 0.06–1.0 ng/mL under optimal conditions. All analytes exhibited good linearity with correlation coefficients of higher than 0.9915. The relative standard deviations for five neonicotinoid insecticides in environmental samples ranged from 1.8 to 16.5%, and good recoveries from 83.5 to 117.0% were obtained, indicating that magnetic zeolitic imidazolate framework 67/graphene oxide composites were feasible for analysis of trace analytes in environmental water samples.     

Hydrothermal Synthesis and Structural Characterization of a Novel Organic—Inorganic Hybrid Compound {[Cu（2,2′—bpy）2]2—Mo8O26}

A novel organic-inorganic hybrid compound {[Cu(2,2′-bpy)2]2Mo8O26} has been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction. The compound crystallizes in the orthorhombic space group, Pna21,with a=2.4164(5),b=1.8281(4),c=1.1877(2)nm,V=5.247(2)nm^3,Z=4,and final R1=0.0331,wR2=0.0727.The structure consists of discrete {[Cu(2,2′-bpy)2]2Mo8O26} clusters,constructed from a β-octamolybdate subunit[Mo8O26]^4- covalently bonded to two [Cu(2,2′-bpy)2]^2 coordination complex cations via bridging oxo groups.In addition,the spectroscopic properties and thernal behavior of this compound have been investigated by spectroscopic techniques (UV-vis,IR,Raman and EPR spectra) and TG analysis.     

Robust Organic/Inorganic Hybrid Porous Thin Films via Breath‐Figure Method and Gelation Process

A novel organic/inorganic hybrid honeycomb patterned porous thin film was prepared using the breath‐figure method combined with a sol‐gel process. An in situ formed gelable block copolymer, formed by mixing poly(styrene‐alt‐maleic anhydride)‐block‐polystyrene (P(St‐a‐MAn)‐b‐PS) and 3‐aminopropyltrimethoxysilane (APS), was used as the structure directing agent. The porous film produced was dipped into an acid aqueous solution to induce a sol‐gel process in the wall of film. As a result of gelation, the structure of this film transformed into a crosslinked silica oxide hybridized with PS, and this film resisted those organic solvents which were once good solvents for the copolymer precursor.

     

Hollow Zn/Co ZIF Particles Derived from Core–Shell ZIF‐67@ZIF‐8 as Selective Catalyst for the Semi‐Hydrogenation of Acetylene

The rational design of metal–organic frameworks (MOFs) with hollow features and tunable porosity at the nanoscale can enhance their intrinsic properties and stimulates increasing attentions. In this Communication, we demonstrate that methanol can affect the coordination mode of ZIF‐67 in the presence of Co²⁺ and induces a mild phase transformation under solvothermal conditions. By applying this transformation process to the ZIF‐67@ZIF‐8 core–shell structures, a well‐defined hollow Zn/Co ZIF rhombic dodecahedron can be obtained. The manufacturing of hollow MOFs enables us to prepare a noble metal@MOF yolk‐shell composite with controlled spatial distribution and morphology. The enhanced gas storage and porous confinement that originate from the hollow interior and coating of ZIF‐8 confers this unique catalyst with superior activity and selectivity toward the semi‐hydrogenation of acetylene.     

Synergetic Effect of Dual Co‐catalysts on the Activity of p‐Type Cu2O Crystals with Anisotropic Facets

Spatial separation of reduction sites and oxidation sites to inhibit the recombination of photogenerated electrons and holes plays a vital role in improving the efficiency of photocatalyst systems. It is very challenging to rationally deposit cocatalysts on the right facets (sites), namely, the reduction cocatalyst on the reduction facets (sites) and the oxidation cocatalyst on the oxidation facets (sites). Herein, we report that the reduction and oxidation cocatalysts can be selectively constructed on the different facets of p‐type Cu₂O crystals with anisotropic facets, but not on the Cu₂O crystal with isotropic facets. The deposition of dual cocatalysts on the different facets resulted in a remarkable synergetic effect in the photocatalytic performance, which could be attributed to the spatial separation of the photogenerated charges between facets. Our work reports an instructive strategy for constructing high‐efficiency photocatalyst systems for solar energy conversion.     

一种基于碘化铅的有机/无机杂化钙钛矿材料传输性能的研究

合成了一种新型的有机/无机杂化钙钛矿(NH3C6H4OC6H4NH3)PbI4, 采用元素分析、紫外-可见光吸收光谱、X射线衍射和透射电镜对其结构进行了表征, 结果表明这种材料具有规则的层状结构, 有序性高. 对这种材料的薄膜进行了伏安测试, 结果表明该材料属于n型半导体, 其电子迁移率达到0.065 cm2•V－1•s－1, 在光电器件领域有着潜在的应用前景.     

Ultra‐Tuning of the Aperture Size in Stiffened ZIF‐8_Cm Frameworks with Mixed‐Linker Strategy for Enhanced CO2/CH4 Separation

ZIF‐8 membrane has the potential for CO₂/CH₄ separation based on size exclusion. But if traditionally prepared by solvothermal methods, it shows only negligible selectivity due to the linker mobility. Here, ≈500 nm‐thin hybrid ZIF‐7_x‐8 membranes with suppressed linker mobility and narrowed window aperture are prepared by a fast current‐driven synthesis (FCDS) within 20 min. The in situ electric field during FCDS allows the formation of stiffened ZIF‐8_Cm as parent skeleton and the mixed‐linker strategy is applied to narrow the aperture size simultaneously. The ZIF‐7₂₂‐8 membrane shows significantly sharpened molecular sieving for CO₂/CH₄ with a separation factor above 25, which soared tenfold compared with other unmodified ZIF‐8 membranes. Additionally, the membrane shows exceptional separation performance for H₂/CH₄ and CO₂/N₂, with separation factors of 71 and 20, respectively. After 180 h temperature swing operation, it still maintains the excellent separation performance.     

Additive‐Free,Robust H2 Production from H2O and DMF by Dehydrogenation Catalyzed by Cu/Cu2O Formed In Situ

Hydrogen production from organic/inorganic hydrides is a promising strategy for the development of novel clean energy resources to replace fossil fuels and satisfy ever‐increasing energy demands. Most current processes involve small flammable chemicals and are catalyzed by noble metals in basic media with the release of the greenhouse gas CO₂. Herein, we describe an alternative pathway for highly efficient and robust H₂ production through a dehydrogenation reaction between water and N ,N ‐dimethylformamide catalyzed by Cu/Cu₂O catalysts formed in situ. The catalysts exhibit high and robust activity for H₂ production. Importantly, the formation of H₂ as the sole gas and the valuable by‐product N ,N ‐dimethylaminoformic acid make this process clean and valuable with 100 % atom economy.     

Controllable Synthesis of Porphyrin‐Based 2D Lanthanide Metal–Organic Frameworks with Thickness‐ and Metal‐Node‐Dependent Photocatalytic Performance

Synthesizing 2D metal–organic frameworks (2D MOFs) in high yields and rational tailoring of the properties in a predictable manner for specific applications is extremely challenging. Now, a series of porphyrin‐based 2D lanthanide MOFs (Ln‐TCPP, Ln=Ce, Sm, Eu, Tb, Yb, TCPP=tetrakis(4‐carboxyphenyl) porphyrin) with different thickness were successfully prepared in a household microwave oven. The as‐prepared 2D Ln‐TCPP nanosheets showed thickness‐dependent photocatalytic performances towards photooxidation of 1,5‐dihydroxynaphthalene (1,5‐DHN) to synthesize juglone. Particularly, the Yb‐TCPP displayed outstanding photodynamic activity to generate O₂^? and ¹O₂. This work not only provides fundamental insights into structure designing and property tailoring of 2D MOFs nanosheets, but also pave a new way to improve the photocatalytic performance.     

Effect of Composition on Surface Properties of Polydimethylsiloxane-based Inorganic/Organic Hybrid Films

Surface properties of the polydimethylsiloxane (PDMS)-based inorganic/organic hybrids films prepared from silanol-terminated PDMS and titanium tetra-isopropoxide (TIP) were investigated with an aim at the application to the thermal-fixation roll for electro-photographic printers. The 300°C-treated hybrid film with the PDMS/TIP molar ratio of 0.5 exerted a relatively high contact angle of water as 115°C. It was found by using Tapping-Mode Atomic Force Microscopy (AFM) that the hybrid film surface changed from lamella structure to sea-island structure with the increase of PDMS content when heat-treated at 150°C, and became homogenous surface over 300°C. The phase-shift detected by AFM was negative shift, showing that hybrid surface became more hydrophobic as the PDMS/TIP molar ratios of 0.35 and 4.0 exhibited excellent toner-offset property of showing no adhesion of toners, suggesting their practical use in the photographic printers.     

In Situ Modification of Metal–Organic Frameworks in Mixed‐Matrix Membranes

Processable films of metal–organic frameworks (MOFs) have been long sought to advance the application of MOFs in various technologies from separations to catalysis. Herein, MOF–polymer mixed‐matrix membranes (MMMs) are described, formed on several substrates using a wide variety of MOF materials. These MMMs can be delaminated from their substrates to create free‐standing MMMs that are mechanically stable and pliable. The MOFs in these MMMs remain highly crystalline, porous, and accessible for further chemical modification through postsynthetic modification (PSM) and postsynthetic exchange (PSE) processes. Overall, the findings here demonstrate a versatile approach to preparing stable functional MMMs that should contribute significantly to the advancement of these materials.     

基于改性亚麻仁油的有机/无机光固化膜的光固化机理及其反应性研究

用亚麻仁油和环戊二烯合成了改性亚麻仁油(NLO)光固化低聚物,其结构用红外光谱(FT-IR)进行了表征.基于改性亚麻仁油、巯基硅氧烷和光引发剂制备了有机/无机杂化光固化膜,对其光固化机理进行了分析,对无机粒子在改性亚麻仁油中的分布用AFM(原子力显微镜)进行了观测,建立了该有机/无机杂化体系的光固化模型.对杂化膜光固化反应性用Photo-差示扫描热分析仪(Photo-Differential Scanning Calorimeter)进行了测试,Photo-DSC测试结果表明:巯基硅氧烷能大大提高改性亚麻仁油体系光固化速率,环烯键对硫醇十分敏感.