Porous Organic Framework Materials Research Articles

Melamine-based nanoscale porous organic frameworks as multifunctional separator modifiers to mitigate the polysulfide shuttle effect in lithium–Sulfur batteries

The shuttling of polysulfides between electrodes in lithium-sulfur (Li-S) batteries significantly impairs cycle stability. This study explores the use of melamine-based nanoscale porous organic frameworks (POFs) as polysulfide reservoirs to modify glass fiber (GF) separators. Melamine was reacted with dibromoalkanes of varying carbon chain lengths (n = 4, 8, and 12) to produce a series of POF materials, POF-Cn, with different nanoscale pore sizes and solubilities. The POF composites, POF-Cn/SP/PVP, which include conductive carbon Super P (SP) and a polyvinylpyrrolidone (PVP) binder, were coated onto GF membranes to create modified separators for Li-S batteries. Batteries with these modified GF separators exhibited higher initial capacities, improved rate performance, and better long-term cycle stability compared to those with non-modified separators. Among the POF composites, POF-C8/SP/PVP exhibited the best performance, with an initial specific capacity of 1392 mAh g-1 at 0.1C and a high capacity retention of 90% after 300 cycles at 0.5C. The enhanced capacity, stability, and rate performance are attributed to the nanoporous structure of POF-C8 and its high nitrogen content, which effectively traps soluble LiPSs and reduces their diffusion toward the Li anode. The good solubility of POF-C8 facilitates uniform dispersion in the modifying layer, promoting efficient polysulfide trapping and maximizing their utilization in electrochemical reactions, aided by the conductive SP in the composite.

In Situ Growth of Well-Aligned MOF Nanoneedle Arrays into Composite Photothermal Membranes for Solar Desalination.

The solar-driven interfacial evaporation (SDIE) technology serves as a clean and facile approach combining seawater desalination to address water shortage and energy crisis. Recently, porous organic framework materials have aroused great attention, and the development of MOF-based composites with significant performance in photothermal conversion and water activation has become one of the important focuses in this field. In this work, an MOF-based composite photothermal membrane (PON@MOF) was prepared via the in situ growth of metal-organic framework (MOF) nanoneedle arrays induced by a pyridine-based organic polymer nanowire network (PON). The PON@MOF membrane possessed an MOF array layer, a PON-induced layer, and a porous support layer. The PON is rich in coordinated nitrogen atoms for anchoring the metal-ion source, and the main role of the PON layer is to provide favorable nucleation sites and orient in situ growth of well-aligned MOF nanoneedle arrays. With the highly conjugated framework of PON@MOF and the light trapping of the nanoarrays strengthening the photothermal conversion as well as the hydrophilic chemical structure facilitating the decrease of the water evaporation enthalpy, the PON@MOF membrane realizes highly efficient thermal vapor conversion. Under solar irradiation (1.0 kW m-2), PON@MOF demonstrated an evaporation rate of 2.14 kg m-2 h-1 and a solar-to-vapor conversion efficiency of 98.5%. Meanwhile, the PON@MOF membrane has excellent salt resistance and stability, highlighting its potential application in desalination. Overall, this work provides a special idea for the structural design of photothermal composites for solar desalination and freshwater production.

Porous Organic Framework Materials (MOF, COF, and HOF) as the Multifunctional Separator for Rechargeable Lithium Metal Batteries.

The separator is an important component in batteries, with the primary function of separating the positive and negative electrodes and allowing the free passage of ions. Porous organic framework materials have a stable connection structure, large specific surface area, and ordered pores, which are natural places to store electrolytes. And these materials with specific functions can be designed according to the needs of researchers. The performance of porous organic framework-based separators used in rechargeable lithium metal batteries is much better than that of polyethylene/propylene separators. In this paper, thethree most classic organic framework materials (MOF, COF, and HOF) are analyzed and summarized. The applications of MOF, COF, and HOF separators in lithium-sulfur batteries, lithium metal anode, and solid electrolytes are reviewed. Meanwhile, the research progress of these three materials in different fields is discussed based on time. Finally, in the conclusion, the problems encountered by MOF, COF, and HOF in different fields as well as their future research priorities are presented. This review will provide theoretical guidance for the design of porous framework materials with specific functions and further stimulate researchers to conduct research on porous framework materials.

Agile Construction of Porous Organic Frameworks Pending Carboxylic Acids and Imidazolium-Based Ionic Liquids for the Efficient Fixation of CO2 to Cyclic Carbonates

The design and facile preparation of ionic liquids (ILs)-functionalized polymer materials is a hot research topic due to their potential wide applications. Herein, taking the reaction advantage of a cyclic anhydride with an alcoholic compound to atom-economically generate a carboxyl ester pending a carboxylic acid moiety, porous organic framework (POF) materials pending carboxylic acids and imidazolium-based ILs (CILs-POFm) were facile synthesized via the acylation reaction of hydroxyl group-functionalized ILs with a styrene maleic anhydride copolymer. The CILs-POFm material properties were facilely adjusted by changing the molar ratio of the mono-hydroxyl-functionalized ILs to the dihydroxyl-functionalized ILs. CILs-POFm materials showed abundant mesoporous structures with a porous diameter of approximately 23.83–48.16 nm, a surface area of up to 274.4 m2 g–1, and a superior CO2 adsorption capacity of 1.71–2.14 mmol g–1 at 273 K and 1 atm. As a proof of concept application, the coupling reaction of epoxides with CO2 to produce cyclic carbonates was studied by using the CILs-POFm materials as catalysts under solvent-free and co-catalyst-free conditions. The findings indicated that the CILs-POF0.5 exhibited a satisfactory catalytic activity and reusability for a large scope of epoxides. Based on the experimental results and density functional theory (DFT) simulations, a synergetic catalytic mechanism was proposed based on the pended carboxylic acidic groups and IL groups. This study not only provided an atom-economic strategy to prepare POFs pending both carboxylic acids and ILs, but also showed new insights into the design of functionalized POF materials with great application potential in energy storage materials, separation, and green catalysis.

The preparation of porosity modified porous organic frameworks via kaolin loading and its improved aromatic organic compounds removal performance

Abstract Porous organic framework material (PAF-45) with a wholly aromatic framework, intrinsic microporosity and π-π conjugation system is used in aromatic pollutant removal. Here, we synthesized a new type of organic porous material (PAF-45/KAL), that was doped with Kaolin during the synthesis of PAF-45. The composite material possesses better performance in adsorption and photocatalytic degradation of aromatic organic compound (AOC) than that of PAF-45. The Kaolin doping changes the polymerization method of PAFs, that turn random polymerization into more fixed-position polymerization. Because of the variation of polymerization method, PAF-45/KAL's pore structure got effectively changed. The composite has not only original micropores but also more mesoporous structure compared with PAF-45. In the static adsorption experiments under room temperature and pressure, PAF-45/KAL could uptake 10–50% more AOC than PAF-45, for example, 50% more for chlorobenzene. Moreover, the photocatalytic ability of PAF-45/KAL gets promoted under visible light illumination, that it could decompose same amount of colorless aniline in shorter time. More importantly, owing to the clay is natural mineral, doping with Kaolin to improve porous organic materials' performance is a low-cost and environmental method.

Porphyrin‐Based Porous Organic Frameworks as Oxygen Reservoirs to Overcome Tumor Hypoxia for Enhanced Photodynamic Therapy

AbstractPhotodynamic therapy kills cancer cells by transferring energy from lasers to tumor‐dissolved O2 to generate highly cytotoxic reactive oxygen species using a photosensitizer. However, the effectiveness of PDT is impaired by the aggregation of photosensitizer and an inadequate oxygen supply in tumors. Here, to overcome above limitations, novel porous organic frameworks (POFs) are reported using photosensitizer porphyrin as building blocks connected through imine condensation reactions. Upon both characteristic with the high porosity and the large surface area, TAPP‐B4‐POFs exhibit excellent O2 carrying capacity. After carrying O2, O2@TAPP‐B4‐POFs generate ROS efficiency in both normoxic and hypoxic environment, which can induce cancer cell apoptosis. Moreover, the antitumor experiment on 4T1 murine breast cancer model demonstrates that O2@TAPP‐B4‐POFs can almost completely suppress tumor progression with good security. These results reveal that photosensitizer‐based POFs materials are promising candidates as oxygen reservoirs to overcome tumor hypoxia for enhanced photodynamic therapy.

Determination of aromatic amines in the urine of smokers using a porous organic framework (JUC-Z2)-coated solid-phase microextraction fiber

A solid-phase microextraction (SPME) fiber coated with a two-dimensional porous organic framework (POF), JUC-Z2, was synthesized by a sol-gel process. The JUC-Z2-coated SPME fiber was combined with gas chromatography-mass spectrometry/mass spectrometry (GC–MS/MS), and a direct analysis method without any derivatization step was developed for the determination of two major harmful aromatic amines (1-naphthylamine, 1-NA; 2-naphthylamine, 2-NA) in the urine of amokers. The new method exhibited satisfactory linearity in the wide range of 0.05–100 μg L−1 with correlation coefficients (R) of 0.9999. The limits of detection are 0.010 and 0.012 ng L−1. The relative standard deviations for repeated extraction (n = 6) with one fiber are less than 7.7%. The JUC-Z2-coated fiber demonstrates obviously superior extraction efficiencies for the two aromatic amines over the commercial fibers (CW/PEG, PA, PDMS/DVB, PDMS, CAR/PDMS, DVB/CAR PDMS). The structure-activity relationship was deeply investigated by the extraction comparison experiment with another similar POF material (PAF-48) and theoretical simulations. The extraction efficiencies of JUC-Z2 for 1-NA and 2-NA are 9.6 and 16.2 times higher than those of PAF-48, and JUC-Z2 has higher binding energies with the aromatic amines than PAF-48. The results indicate that the N atom on the JUZ-Z2 framework played a crucial role for adsorbing aromatic amines. Finally, the novel fiber has been successfully used to detect 1-NA and 2-NA in the urine of smokers.

Synthesis and Catalytic Properties of New Metalloporphyrin‐Based Porous Organic Framework Materials with Single and Accessible Sites

AbstractIt is a big challenge to homogenize heterogeneous catalysts with molecular catalytic performance. With this target in mind, herein, we describe a facile strategy for direct incorporation of single catalytic sites in 3D open porous aromatic frameworks (PAFs). The synthesis of the PAF (denoted as PAF‐76) as well as its derivatives (PAF‐76‐M, M=Fe, Mn, Zn) was achieved by the use of tetrakis(4‐bromophenyl)methane as tetrahedral nodes and tetrakis(4‐bromophenyl)porphyrin as planar nodes. The connection of monomers into an extended network of PAF‐76 was monitored by 13C NMR and FTIR spectroscopies. The prepared PAF‐76s showed 3D porous structures with surface areas of 450–700 m2 g−1, pore volumes of 0.3–0.4 cm3 g−1, and pore sizes around 1.2 nm. The direct incorporation of metalloporphyrin components into the PAF‐76‐M frameworks has allowed the uniform distribution of metal ionic sites throughout the PAF‐76‐M particles. The combined merits of isolated metal sites and suitable pore size make PAF‐76 a good candidate for heterogeneous catalysis. The catalytic performances of the porphyrin/metalloporphyrin‐based active sites in the PAF‐76s were evaluated by aerobic oxidation reactions of styrene, which are usually carried out with homogeneous systems. Metal‐functionalized PAF‐76s (PAF‐76‐M) exhibit enhanced turnover frequencies for styrene conversion (16.9–50.9 mol mol(M)−1 h−1) compared with molecular catalysts (0–35.0 mol mol(M)−1 h−1), and improved selectivity toward phenylacetaldehyde (85.7–99 %) in contrast to their corresponding monomers (0–75.5 %). The robustness of PAF‐76 in terms of high thermal stability, good recyclability, and excellent solvent resistance showed that these PAF‐76 materials hold great promise for developing heterogeneous catalysts.

Construction of sole benzene ring porous aromatic frameworks and their high adsorption properties.

Porous organic frameworks (POFs), with their excellent performance in catalysis, electricity, sensor, gas storage, and separation, have attracted a great deal of attention from researchers all over the world. Generally, the monomers of POF materials require a rigid three-dimensional molecule configuration together with special functional groups, as well as being triggered by noble metal catalysts. Here we report a low-cost and easy-construction strategy for synthesizing PAF materials. A series of flat multi-benzene compounds are selected as building units, and those phenyl rings could couple together to form polymeric skeletons. The BET surface areas of resulting PAFs are moderate, ranging from 777 to 972 m(2) g(-1). However, they unexpectedly exhibit superior gas sorption capacities. At 1.0 bar and 77 K, the H2 uptake of PAF-48 reaches 215 cm(3) g(-1). In addition, PAF-49 shows excellent performance in carbon dioxide and methane sorption, with values of 104 and 35 cm(3) g(-1), respectively. With those adsorption properties, these PAF materials could be considered as potential candidates for energetic gas adsorbents.

ChemInform Abstract: Topology‐Directed Design of Porous Organic Frameworks and Their Advanced Applications

AbstractReview: 109 refs.

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.