Redox Active Mesoporous Hybrid Materials by In situ Syntheses with Urea‐linked Triethoxysilylated Phenothiazines

Triethoxysilyl functionalized phenothiazinyl ureas were synthesized and immobilized by in situ synthesis into mesoporous hybrid materials. The designed precursor molecules influence the structure of the final materials and the intermolecular distance of the phenothiazines. XRD and N₂ adsorption measurements indicate the presence of highly ordered two‐dimensional hexagonally structured functional materials, while the incorporation of the organic compounds in the solid materials was proved by means of ¹³C and ²⁹Si solid state NMR spectroscopy as well as by FT‐IR spectroscopy. Upon oxidation with (NO)BF₄ or SbCl₅, stable phenothiazine radical cations were generated in the pores of the materials, which was detected by means of UV/Vis, emission, and EPR spectroscopies.     

New Microporous Materials for Acetylene Storage and C2H2/CO2 Separation: Insights from Molecular Simulations

Force‐field based grand‐canonical Monte Carlo simulations are used to investigate the acetylene and carbon dioxide uptake capacity, as well as the C₂H₂/CO₂ adsorption selectivity of three novel microporous materials: Magnesium formate, Cu₃(btc)₂, and cucurbit[6]uril. Because no comparable computational studies of acetylene adsorption have been reported so far, the study focuses on systems for which experimental data are available to permit a thorough validation of the simulation results. The results for magnesium formate are in excellent agreement with experiment. The simulation predicts a high selectivity for acetylene over CO₂, which can be understood from a detailed analysis of the structural features that determine the affinity of Mg‐formate towards C₂H₂. For Cu₃(btc)₂, preliminary calculations reveal the necessity to include the interaction of the sorbate molecules with the unsaturated metal sites, which is done by means of a parameter adjustment based on ab‐initio calculations. In spite of the high C₂H₂ storage capacity, the C₂H₂/CO₂ selectivity of this material is very modest. The simulation results for the porous organic crystal cucurbit[6]uril show that the adsorption characteristics that have been observed experimentally, particularly the very high isosteric heat of adsorption, cannot be understood when an ideal structure is assumed. It is postulated that structural imperfections play a key role in determining the C₂H₂ adsorption behavior of this material, and this proposition is supported by additional calculations.     

Development of Sulfonic-Acid-Functionalized Mesoporous Materials: Synthesis and Catalytic Applications

Sulfonic acid based mesostructures (SAMs) have been developed in recent years and have important catalytic applications. The primary applications of these materials are in various organic synthesis reactions, such as multicomponent reactions, carbon–carbon bond couplings, protection reactions, and Fries and Beckman rearrangements. This review aims to provide an overview of the recent developments in the field of SAMs with a particular emphasis on the reaction scope and advantages of heterogeneous solid acid catalysts.     

A Zinc Phthalocyanine Based Periodic Mesoporous Organosilica Exhibiting Charge Transfer to Fullerenes

Periodic mesoporous organosilica (PMO) materials offer a strategy to position molecular semiconductors within a highly defined, porous network. We developed thin films of a new semiconducting zinc phthalocyanine‐bridged PMO exhibiting a face‐centered orthorhombic pore structure with an average pore diameter of 11 nm. The exceptional degree of order achieved with this PMO enabled us to create thin films consisting of a single porous domain throughout their entire thickness, thus providing maximal accessibility for subsequent incorporation of a complementary phase. The phthalocyanine building blocks inside the pore walls were found to be well‐aggregated, enabling electronic conductivity and extending the light‐harvesting capabilities to the near IR region. Ordered 3D heterojunctions capable of promoting photo‐induced charge transfer were constructed by impregnation of the PMO with a fullerene derivative. When integrated into a photovoltaic device, the infiltrated PMO is capable of producing a high open‐circuit voltage and a considerable photocurrent, which represents a significant step towards potential applications of PMOs in optoelectronics.     

Hybrid Ultra‐Microporous Materials for Selective Xenon Adsorption and Separation

The demand for Xe/Kr separation continues to grow due to the industrial significance of high‐purity Xe gas. Current separation processes rely on energy intensive cryogenic distillation. Therefore, less energy intensive alternatives, such as physisorptive separation, using porous materials, are required. Herein we show that an underexplored class of porous materials called hybrid ultra‐microporous materials (HUMs) affords new benchmark selectivity for Xe separation from Xe/Kr mixtures. The isostructural materials, CROFOUR‐1‐Ni and CROFOUR‐2‐Ni, are coordination networks that have coordinatively saturated metal centers and two distinct types of micropores, one of which is lined by CrO₄^2? (CROFOUR) anions and the other is decorated by the functionalized organic linker. These nets offer unprecedented selectivity towards Xe. Modelling indicates that the selectivity of these nets is tailored by synergy between the pore size and the strong electrostatics afforded by the CrO₄^2? anions.     

多金属氧酸盐/TiO2介孔杂化材料的合成及光催化性能研究

采用蒸发诱导自组装法合成了介孔TiO2,并将表面含有Si-OH基团的钨磷酸盐衍生物(Bu4N)3PW11O39-[O(SiOH)2](TBAPW11Si2)嫁接到乙醇回流脱模的介孔TiO2上,合成了TBAPW11Si2/TiO2介孔杂化材料.采用IR、XRD、N2吸附-脱附、TEM、ICP-AES对样品的结构和组成进行了表征.结果表明,TBAPW11Si2与TiO2之间的共价键联是通过表面Si-OH和Ti-OH间的缩合进行的;TiO2表面足够的Ti-OH基团和一定温度的焙烧是这一缩合的必要条件.与TiO2载体相比,嫁接了TBAPW11Si2的杂化样品,锐钛矿相的结晶度略有增加;但表面积、孔容和孔径均有所减小,且随TBAPW11Si2负载量的增加而降低.光催化降解甲基橙的结果显示,杂化样品表现出比载体TiO2高得多的催化活性,甚至与高结晶度的商品光催化剂P25相当,显示出多金属氧酸盐-TiO2协同作用的优越性.     

A New Synthetic Route to Microporous Silica with Well‐Defined Pores by Replication of a Metal–Organic Framework

Microporous amorphous hydrophobic silica materials with well‐defined pores were synthesized by replication of the metal–organic framework (MOF) [Cu₃(1,3,5‐benzenetricarboxylate)₂] (HKUST‐1). The silica replicas were obtained by using tetramethoxysilane or tetraethoxysilane as silica precursors and have a micro–meso binary pore system. The BET surface area, the micropore volume, and the mesopore volume of the silica replica, obtained by means of hydrothermal treatment at 423 K with tetraethoxysilane, are 620 m²g^?1, 0.18 mL g^?1, and 0.55 mL g^?1, respectively. Interestingly, the silica has micropores with a pore size of 0.55 nm that corresponds to the pore‐wall thickness of the template MOF. The silica replica is hydrophobic, as confirmed by adsorption analyses, although the replica has a certain amount of silanol groups. This hydrophobicity is due to the unique condensation environment of the silica precursors in the template MOF.     

共价键联的PW11/TiO2介孔杂化材料的合成及其光催化性能

采用二次嫁接的方法,将Keggin结构的缺位钨磷酸盐PW11嫁接到介孔TiO2的表面,得到PW11/TiO2杂化样品。采用IR、低温N2吸附、XRD、TEM和ICP-AES等对样品的结构、PW11负载量以及键联机理进行了表征和研究,对样品光催化降解甲基橙的性能进行了考察。 结果显示,用蒸发诱导自组装法合成的TiO2,焙烧前结构松散,可部分水解并与PW11反应,生成PW11Ti物种,后者与TiO2骨架缩合,从而实现PW11的键联嫁接。 与纯TiO2相比,杂化样品中锐钛矿相的结晶度稍有降低,孔径、孔容减小,但是对甲基橙的光催化降解活性却明显增加,显然这是PW11和TiO2间发生了“协同效应”所致。     

Controlling the BET Surface Area of Porous Carbon by Using the Cd/C Ratio of a Cd–MOF Precursor and Enhancing the Capacitance by Activation with KOH

Herein, four new cadmium metal–organic frameworks (Cd–MOFs), [Cd(bib)(bdc)]_∞ ( 1 ), [Cd(bbib)(bdc)(H₂O)]_∞ ( 2 ), [Cd(bibp)(bdc)]_∞ ( 3 ), and [Cd₂(bbibp)₂(bdc)₂(H₂O)]_∞ ( 4 ), have been constructed from the reaction of Cd(NO₃)₂ ? 4 H₂O with 1,4‐benzenedicarboxylate (H₂bdc) and structure‐related bis(imidazole) ligands (1,4‐bis(imidazol‐1‐yl)benzene (bib), 1,4‐bis(benzoimidazol‐1‐yl)benzene (bbib), 4,4′‐bis(imidazol‐1‐yl)biphenyl (bibp), and 4,4′‐bis(benzoimidazol‐1‐yl)biphenyl (bbibp)) under solvothermal conditions. Cd–MOF 1 shows a 2D (4,4) lattice with parallel interpenetration, whereas 2 displays an interesting 3D interpenetrating dia network, 3 exhibits an unusual 3D interpenetrating dmp network, and 4 presents a 3D self‐catenated pillar‐layered framework with a Schäfli symbol of [4³ ? 6³]₂ ? [4⁶ ? 6¹⁶ ? 8⁶]. The structural diversity indicates that the backbone of the bis(imidazole) ligand (including the terminal group and spacer) plays a crucial role in the assembly of mixed‐ligand frameworks. By using the pore‐forming effect of cadmium vapor, for the first time we have utilized these Cd–MOFs as precursors to further prepare porous carbon materials (PCs) in a calcination–thermolysis procedure. These PCs show different porous features that correspond to the topological structures of Cd–MOFs. Significantly, it was found that the specific surface area and capacitance of PCs are tuned by the Cd/C ratio of the MOF. Furthermore, the as‐synthesized PCs were processed with KOH to obtain activated porous carbon materials (APCs) with higher specific surface area and porosity, which greatly promoted the energy‐storage capacity. After full characterization, we found that APC‐bib displays the largest specific surface area (1290 m² g^?1) and total pore volume (1.37 cm³ g^?1) of this series of carbon materials. Consequently, APC‐bib demonstrates the highest specific capacitance of 164 F g^?1 at a current density of 0.5 A g^?1, and also excellent retention of capacitance (≈89.4 % after 5000 cycles at 1 A g^?1). Therefore, APC‐bib has great potential as the electrode material in a supercapacitor.     

Solvatochromic Behavior of Chiral Mesoporous Metal–Organic Frameworks and Their Applications for Sensing Small Molecules and Separating Cationic Dyes

Two anionic metal–organic frameworks (MOFs) with 1D mesoporous tubes ( 1 ) and chiral mesoporous cages ( 2 ) have been rationally constructed by means of a predesigned size‐extended hexatopic ligand, namely, 5,5′,5′′‐(1,3,5‐triazine‐2,4,6‐triyl)tris‐ (azanediyl)triisophthalate (TATAT). Charge neutrality is achieved by protonated dimethylamine cations. Notably, the two MOFs can be used to separate large molecules based on ionic selectivity rather than the size‐exclusion effect so far reported in the literature. Owing to the imino triazine backbone and carboxyl groups of the hexatopic ligand, which provide important host–guest interactions, rare solvatochromic phenomena of 1 and 2 are observed on incorporating acetone and ethanol guests. Furthermore, guest‐dependent luminescence properties of compound 2 were investigated, and the results show that luminescence intensity is significantly enhanced in toluene and benzene, while quenching effects are observed in acetone and ethanol. Thus, compound 2 may be a potential material for luminescent probes.     

新型层状有机聚合物-无机杂化磷酸铝(AlPS-PVPA)催化剂载体材料的合成及表征

以苯乙烯-苯乙烯基膦酸共聚物、磷酸二氢钠作磷(膦)源,在温和的条件下,通过调节有机膦酸和无机磷酸的比例,合成了一系列不同化学计量比的聚(苯乙烯-苯乙烯基膦酸)-磷酸铝有机聚合物-无机杂化材料。通过FTIR、TG、N2吸附、XRD、SEM和TEM等表征手段对其进行了表征,并提出了其理想的结构模型。结果表明,这类杂化材料具有规则的层状结构和较高的热稳定性,作为催化剂载体具有潜在的应用价值。     

Fabrication of Microporous Metal–Organic Frameworks in Uninterrupted Mesoporous Tunnels: Hierarchical Structure for Efficient Trypsin Immobilization and Stabilization

Hierarchically porous metal–organic frameworks (HP‐MOFs) are promising in various applications. Most reported HP‐MOFs are prepared based on the generation of mesopores in microporous frameworks, and the formed mesopores are connected by microporous channels, limiting the accessibility of mesopores for bulky molecules. A hierarchical structure is formed by constructing microporous MOFs in uninterrupted mesoporous tunnels. Using the confined space in as‐prepared mesoporous silica, highly dispersed metal precursors for MOFs are coated on the internal surface of mesoporous tunnels. Ligand vapor‐induced crystallization is employed to enable quantitative formation of MOFs in situ, in which sublimated ligands diffuse into mesoporous tunnels and react with metal precursors. The obtained hierarchically porous composites exhibit record‐high adsorption capacity for the bulky molecule trypsin. The thermal and storage stability of trypsin is improved upon immobilization on the composites.     

Microporous Metal–Organic Frameworks for Gas Separation

Microporous metal–organic frameworks (MOFs) are comparatively new porous materials. Because the pores within such MOFs can be readily tuned through the interplay of both metal‐containing clusters and organic linkers to induce their size‐selective sieving effects, while the pore surfaces can be straightforwardly functionalized to enforce their different interactions with gas molecules, MOF materials are very promising for gas separation. Furthermore, the high porosities of such materials can enable microporous MOFs with optimized gas separation selectivity and capacity to be targeted. This Focus Review highlights recent significant advances in microporous MOFs for gas separation.     

Diol‐Linked Microporous Networks of Cubic Siloxane Cages

A new class of inorganic–organic hybrid porous materials has been synthesized by a reaction between octa(hydridosilsesquioxane) (H₈Si₈O₁₂), which has a double‐four‐ring (D4R) structure, and various diols, such as 1,3‐propanediol (PD), 1,4‐cyclohexanediol (CHD), and 1,3‐adamantanediol (AD). Solid‐state ²⁹Si magic‐angle‐spinning NMR spectroscopic analysis confirmed that most of the corner Si? H groups reacted with diols to form Si‐O‐C bonds with retention of the D4R cage. Nitrogen adsorption–desorption studies showed that the products are microporous solids with high BET surface areas (up to ≈580 m² g^?1 for CHD‐ and AD‐linked products). If n‐alkanediols are used as linkers, the surface area becomes smaller as the number of carbon atoms is increased. The thermal and hydrolytic stability of the products strongly depend on the type of diol linkers. The highest stabilities are found for the AD‐linked products, which are thermally stable up to around 400 °C and remain intact even after being soaked in water for 1 day. In contrast, the PD‐linked product is easily hydrolyzed in water to give microporous silica. These results offer a new route toward a series of silica‐based porous materials with unique structures and properties.