Triptycene-Based Polymers of Intrinsic Microporosity: Organic Materials That Can Be Tailored for Gas Adsorption

Exploring Nanomaterials for Hydrogen Storage: Advances, Challenges, and Perspectives

Hydrogen energy heralded for its environmentally friendly, renewable, efficient, and cost-effective attributes, stands poised as the primary alternative to fossil fuels in the future. Despite its great potential, the low volumetric density presents a formidable challenge in hydrogen storage. Addressing this challenge necessitates exploring effective storage techniques for a sustainable hydrogen economy. Solid-state hydrogen storage in nanomaterials (physically or chemically) holds promise for achieving large-scale hydrogen storage applications. Such approaches offer benefits, including safety, compactness, lightness, reversibility, and efficient generation of pure hydrogen fuel under mild conditions. This article presents solid-state nanomaterials, specifically nanoporous carbons (activated carbon, carbon fibers), metal-organic frameworks, covalently connected frameworks, nanoporous organic polymers, and nanoscale metal hydrides. Furthermore, new developments in hydrogen fuel cell technology for stationary and mobile applications have been demonstrated. The review outlines significant advancements thus far, identifies key barriers to practical implementation, and presents a perspective for future sustainable energy research. It concludes with recommendations to enhance hydrogen storage performance for cost-effective and long-lasting utilization.

Penetrant-induced plasticization in microporous polymer membranes

Penetrant-induced plasticization has prevented the industrial deployment of many polymers for membrane-based gas separations. With the advent of microporous polymers, new structural design features and unprecedented property sets are now accessible under controlled laboratory conditions, but property sets can often deteriorate due to plasticization. Therefore, a critical understanding of the origins of plasticization in microporous polymers and the development of strategies to mitigate this effect are needed to advance this area of research. Herein, an integrative discussion is provided on seminal plasticization theory and gas transport models, and these theories and models are compared to an exhaustive database of plasticization characteristics of microporous polymers. Correlations between specific polymer properties and plasticization behavior are presented, including analyses of plasticization pressures from pure-gas permeation tests and mixed-gas permeation tests for pure polymers and composite films. Finally, an evaluation of common and current state-of-the-art strategies to mitigate plasticization is provided along with suggestions for future directions of fundamental and applied research on the topic.

Synthesis of 12-Connected Three-Dimensional Covalent Organic Framework with lnj Topology

The structural exploration of three-dimensional covalent organic frameworks (3D COFs) is of great significance to the development of COF materials. Different from structurally diverse MOFs, which have a variety of connectivity (3-24), now the valency of 3D COFs is limited to only 4, 6, and 8. Therefore, the exploration of organic building blocks with higher connectivity is a necessary path to broaden the scope of 3D COF structures. Herein, for the first time, we have designed and synthesized a 12-connected triptycene-based precursor (triptycene-12-CHO) with 12 symmetrical distributions of aldehyde groups, which is also the highest valency reported until now. Based on this unique 12-connected structure, we have successfully prepared a novel 3D COF with lnj topology (termed 3D-lnj-COF). The as-synthesized 3D COF exhibits honeycomb main pores and permanent porosity with a Brunauer-Emmett-Teller surface area of 1159.6 m2 g-1. This work not only provides a strategy for synthesizing precursors with a high connectivity but also provides inspiration for enriching the variety of 3D COFs.

Development of Liquid Organic Hydrogen Carriers for Hydrogen Storage and Transport

The storage and transfer of energy require a safe technology to mitigate the global environmental issues resulting from the massive application of fossil fuels. Fuel cells have used hydrogen as a clean and efficient energy source. Nevertheless, the storage and transport of hydrogen have presented longstanding problems. Recently, liquid organic hydrogen carriers (LOHCs) have emerged as a solution to these issues. The hydrogen storage technique in LOHCs is more attractive than those of conventional energy storage systems like liquefaction, compression at high pressure, and methods of adsorption and absorption. The release and acceptance of hydrogen should be reversible by LOHC molecules following favourable reaction kinetics. LOHCs comprise liquid and semi-liquid organic compounds that are hydrogenated to store hydrogen. These hydrogenated molecules are stored and transported and finally dehydrogenated to release the required hydrogen for supplying energy. Hydrogenation and dehydrogenation are conducted catalytically for multiple cycles. This review elaborates on the characteristics of different LOHC molecules, based on their efficacy as energy generators. Additionally, different catalysts used for both hydrogenation and dehydrogenation are discussed.

Mini-review on the novel synthesis and potential applications of carbazole and its derivatives

Microporous organic polymers (MOPs) are a new type of porous materials, which have advantages of synthetic diversity, chemical and physical stability, microporous size controllability, etc. MOPs indicate broad applications in various fields such as heterogeneous catalysis, gas adsorption, separation, and storage. In recent years, MOPs have attracted an enormous attention in greenhouse gas capture due to their great potential in physisorptive gas storage. Carbazole and its derivatives have been studied extensively as Metal-Organic Polyhedra (MOPs) building blocks due to their unique structural features and versatile functionalization possibilities. This paper systematically reviews the synthesis, characterization and application of carbazole-based polymers, and relationship of structures and properties of these polymers. The application of the polymers in carbon dioxide (CO₂) capture field is analysed taking advantage of their adjustable microporous structure and electron rich properties. This review also provides novel insights regarding functional polymer materials that have high ability of greenhouse gas capture and absorbing selectivity will be obtained by reasonable molecular design and efficient synthesis.

Polymers of Intrinsic Microporosity Based on Dibenzodioxin Linkage: Design, Synthesis, Properties, and Applications

The development of polymers of intrinsic microporosity (PIMs) over the last two decades has established them as a distinct class of microporous materials, which combine the attributes of microporous solid materials and the soluble nature of glassy polymers. Due to their solubility in common organic solvents, PIMs are easily processable materials that potentially find application in membrane-based separation, catalysis, ion separation in electrochemical energy storage devices, sensing, etc. Dibenzodioxin linkage, Tröger's base, and imide bond-forming reactions have widely been utilized for synthesis of a large number of PIMs. Among these linkages, however, most of the studies have been based on dibenzodioxin-based PIMs. Therefore, this review focuses precisely on dibenzodioxin linkage chemistry. Herein, the design principles of different rigid and contorted monomer scaffolds are discussed, as well as synthetic strategies of the polymers through dibenzodioxin-forming reactions including copolymerization and postsynthetic modifications, their characteristic properties and potential applications studied so far. Towards the end, the prospects of these materials are examined with respect to their utility in industrial purposes. Further, the structure-property correlation of dibenzodioxin PIMs is analyzed, which is essential for tailored synthesis and tunable properties of these PIMs and their molecular level engineering for enhanced performances making these materials suitable for commercial usage.

Construction of palladium porphyrins and triptycene photo-activated nanomaterial for enhanced colorimetric detection and inactivation of bacteria

In the face of increasing bacterial resistance, design of high-performing and dual-functional nanomaterials to satisfy the requirements for both detecting and eradicating bacteria is of immense importance, but still remains a great challenge. Herein, a hierarchically three-dimensional (3D) porous organic frameworks (PdPPOP_HBTT) was rationally designed and fabricated for the first time to realize ideal simultaneous detection and eradication of bacteria. PdPPOP_HBTT covalently integrated palladium 5,10,15,20-tetrakis-(4'-bromophenyl) porphyrin (PdTBrPP, an excellent photosensitizer) with 2,3,6,7,12,13-hexabromotriptycene (HBTT, a 3D building module). The resulting material had outstanding NIR absorption, narrow bad gap and robust singlet oxygen (¹O₂) production capacity, which is responsible for the sensitive detection and effective removal of bacteria. We successfully realized the colorimetric detection of S. aureus and the efficient removal of S. aureus and E. coli. The first-principles calculations found at the highly activated ¹O₂ derived from the 3D conjugated periodic structures and ample palladium adsorption site in PdPPOP_HBTT. The bacterial infection wound model revealed that PdPPOP_HBTT possesses good disinfection ability and negligible side effect to normal tissue in vivo. This finding provides an innovative strategy for designing individual porous organic polymer (POPs) with multi-function and also broaden the applications of POPs as powerful nonantibiotic type of antimicrobials.

Polydimethylsiloxane/Magnesium Oxide Nanosheet Mixed Matrix Membrane for CO2 Separation Application

Carbon dioxide (CO₂) concentration is now 50% higher than in the preindustrial period and efforts to reduce CO₂ emission through carbon capture and utilization (CCU) are blooming. Membranes are one of the attractive alternatives for such application. In this study, a rubbery polymer polydimethylsiloxane (PDMS) membrane is incorporated with magnesium oxide (MgO) with a hierarchically two-dimensional (2D) nanosheet shape for CO₂ separation. The average thickness of the synthesized MgO nanosheet in this study is 35.3 ± 1.5 nm. Based on the pure gas separation performance, the optimal loading obtained is at 1 wt.% where there is no observable significant agglomeration. CO₂ permeability was reduced from 2382 Barrer to 1929 Barrer while CO₂/N₂ selectivity increased from only 11.4 to 12.7, and CO₂/CH₄ remained relatively constant when the MMM was operated at 2 bar and 25 °C. Sedimentation of the filler was observed when the loading was further increased to 5 wt.%, forming interfacial defects on the bottom side of the membrane and causing increased CO₂ gas permeability from 1929 Barrer to 2104 Barrer as compared to filler loading at 1 wt.%, whereas the CO₂/N₂ ideal selectivity increased from 12.1 to 15.0. Additionally, this study shows that there was no significant impact of pressure on separation performance. There was a linear decline of CO₂ permeability with increasing upstream pressure while there were no changes to the CO₂/N₂ and CO₂/CH₄ selectivity.

A Triptycene-Based 2D MOF with Vertically Extended Structure for Improving the Electrocatalytic Performance of CO2 to Methane

Two-dimensional conductive metal-organic frameworks (2D-c-MOFs) have attracted extensive attention owing to their unique structures and physical-chemical properties. However, the planarly extended structure of 2D-c-MOFs usually limited the accessibility of the active sites. Herein, we designed a triptycene-based 2D vertically conductive MOF (2D-vc-MOF) by coordinating 2,3,6,7,14,15-hexahydroxyltriptycene (HHTC) with Cu²⁺ . The vertically extended 2D-vc-MOF(Cu) possesses a weak interlayer interaction, which leads to a facile exfoliation to the nanosheet. Compared with the classical 2D-c-MOFs with planarly extended 2D structures, 2D-vc-MOF(Cu) exhibits a 100 % increased catalytic activity in terms of turnover number and a two-fold increased selectivity. Density functional theory (DFT) calculations further revealed that higher activity originated from the lower energy barriers of the vertically extended 2D structures during the CO₂ reduction reaction process.

Influence of Triptycene Annulation on the Photochromism of Diphenylnaphthopyrans: Entropic Control of Thermal Reversion

Regioisomeric naphthopyrans annulated with triptycene, i. e., Prox-NP and Dist-NP, display divergent photochromic behaviors. While steady-state photolysis of Dist-NP led to a very labile colored intermediate that is not observable at room temperature, Prox-NP yielded a remarkably stable species characterized by X-ray crystallography as the TT isomer of o-quinonoid intermediate (Prox-NPQ) with t_1/2 ca. 0.18 years at 298 K. The kinetic analysis of thermal reversion reveals that the bleaching of Prox-NPQ is entropically controlled; the steric effect due to the rigid triptycene scaffold renders Prox-NP a highly constrained system such that the photogenerated colored o-quinonoid form is more entropically relaxed. This constitutes the first instance of an entropically-controlled thermal reversion for the celebrated class of photochromic naphthopyrans. Based on the response of Prox-NP and its colored intermediate Prox-NPQ to different stimuli, namely, light, heat, and acid, the molecular system can be likened to a logic gate with the 'INHIBIT' function.

Tröger's Base Network Polymers of Intrinsic Microporosity (TB-PIMs) with Tunable Pore Size for Heterogeneous Catalysis

Heterogeneous catalysis plays a pivotal role in the preparation of value-added chemicals, and it works more efficiently when combined with porous materials and supports. Because of that, a detailed assessment of porosity and pore size is essential when evaluating the performance of new heterogeneous catalysts. Herein, we report the synthesis and characterization of a series of novel microporous Tröger’s base polymers and copolymers (TB-PIMs) with tunable pore size. The basicity of TB sites is exploited to catalyze the Knoevenagel condensation of benzaldehydes and malononitrile, and the dimension of the pores can be systematically adjusted with an appropriate selection of monomers and comonomers. The tunability of the pore size provides the enhanced accessibility of the catalytic sites for substrates, which leads to a great improvement in conversions, with the best results achieving completion in only 20 min. In addition, it enables the use of large benzaldehydes, which is prevented when using polymers with very small pores, typical of conventional PIMs. The catalytic reaction is more efficient than the corresponding homogeneous counterpart and is ultimately optimized with the addition of a small amount of a solvent, which facilitates the swelling of the pores and leads to a further improvement in the performance and to a better carbon economy. Molecular dynamic modeling of the copolymers’ structures is employed to describe the swellability of flexible chains, helping the understanding of the improved performance and demonstrating the great potential of these novel materials.

Homoconjugation in triptycenes: an inquiry through photochromism

Stabilization of the fleeting photogenerated o-quinonoid colored intermediate of diphenylpyran-annulated triptycene (Trip-chrom) lends credence to homoconjugation.

Triptycene Derivatives: From Their Synthesis to Their Unique Properties

Since the first preparation of triptycene, great progress has been made with respect to its synthesis and the understanding of its properties. Interest in triptycene-based systems is intense; in recent years, advances in the synthetic methodology and properties of new triptycenes have been reported by researchers from various fields of science. Here, an account of these new developments is given and placed in reference to earlier pivotal works that underpin the field. First, we discuss new approaches to the synthesis of new triptycenes. Progress in the regioselective synthesis of sterically demanding systems is discussed. The application of triptycenes in catalysis is also presented. Next, progress in the understanding of the relations between triptycene structures and their properties is discussed. The unique properties of triptycenes in the liquid and solid states are elaborated. Unique interactions, which involve triptycene molecular scaffolds, are presented. Molecular interactions within a triptycene unit, as well as between triptycenes or triptycenes and other molecules, are also evaluated. In particular, the summary of the synthesis and useful features will be helpful to researchers who are using triptycenes as building blocks in the chemical and materials sciences.

A selective and inert stationary phase combining triptycene with tocopheryl polyethylene glycol succinate for capillary gas chromatography

This work reports a selective and inert triptycene-based stationary phase (TPT) combining the triptycene framework with tocopheryl polyethylene glycol succinate (TPGS) units for capillary gas chromatography (GC). The TPT stationary phase was physically coated onto a capillary column by static coating method with the column efficiency of 4200 plates/m and moderate polarity. As demonstrated, the TPT column exhibited high inertness towards organic bases, including basic heterocycles, aliphatic and aromatic amines, showing distinct advantages over the TPGS and commercial columns. Also, the TPT column displayed high-resolution performance towards the isomers of methylpyridines, toluidines, xylidines and alkanes (C6-C8). Moreover, it showed excellent separation repeatability and reproducibility with RSD values in the range of 0.03%-0.07% for run-to-run, 0.12%-0.18% for day-to-day and 2.3%-3.6% for column-to- column (n = 4). Its applications to purity test of chemical products and to GC-MS analysis of the essential oil of Artemisia annua L. demonstrated its good potential for practical analyses. The present work has novelty in constructing highly selective and inert stationary phases and providing a feasible strategy for concurrently addressing the related problems in GC analyses. Its methodology and findings is of important value in terms of fundamental researches and practical applications.

Charge Transfer from Donor to Acceptor in Conjugated Microporous Polymer for Enhanced Photosensitization

Photosensitization associated with light absorption and energy/electron-transfer represents the central processes for photosynthesis. However, it's still a challenge to develop a heavy-atom-free (HAF) strategy to improve the sensitizing ability of polymeric photosensitizers. Herein, we propose a new protocol to significantly improve the photosensitization by decorating mother conjugated microporous polymer (CMP-1) with polycyclic aromatic hydrocarbons (PAHs), resulting in a series of CMPs (CMP-2-4). Systematic study reveals that covalent modification with PAHs can transfer charge to Bodipy in CMP to further facilitate both intersystem crossing and electron-hole separation, which can dramatically boost energy-/electron-transfer reactions. Remarkably, CMP-2 as a representative CMP can efficiently drive the photosynthesis of methyl phenyl sulfoxide with 92 % yield, substantially higher than that of CMP-1 (32 %). Experiments and theory calculations demonstrate the structure-property-activity relationship of these CMPs, opening a new horizon for developing HAF heterogeneous photosensitizers with highly efficient sensitizing activity by rational structure regulation at a molecular level.

Irreversible deformation of hyper-crosslinked polymers after hydrogen adsorption

Hyper-crosslinked polymers (HCPs) have been produced by the Friedel-Crafts reaction using anthracene, benzene, carbazole or dibenzothiophene as precursors and dimethoxymethane as crosslinker, and the effect of graphene oxide (GO) addition has been studied. The resulting HCPs were highly microporous with BET areas (A_BET) between 590 and 1120 m²g^-1. The benzene-derived HCP (B1FeM2) and the corresponding composite with GO (B1FM2-GO) exhibited the highest A_BET and were selected to study their hydrogen adsorption capacities in the pressure range of 0.1 - 14 MPa at 77 K. The maximum H₂ excess uptake was 2.1 and 2.0 wt% for B1FeM2 and B1FeM2-GO, respectively, at 4 MPa and 77 K. The addition of GO reduced the specific surface area but increased the density of the resultant HCP-GO composites, which is beneficial for practical applications and proves that materials giving higher gravimetric storage capacities are not necessarily those that offer higher volumetric capacities. H₂ adsorption-desorption cycles up to 14 MPa showed irreversible deformation of both HCP and HCP-GO materials, which calls into question their application for hydrogen adsorption at pressures above 4 MPa.

Role of ultramicropores in the remarkable gas storage in hypercrosslinked polystyrene networks studied by positron annihilation

In this paper, hypercrosslinked polystyrene (HCLPS) networks were synthesized by radical bulk polymerization and Friedel-Crafts alkylation reactions using vinylbenzyl-co-divinylbenzene chloride (VBC-DVB) as the precursors. A series of HCLPS was prepared with varying content of DVB from 0 to 10% in the precursor. Both N2 adsorption and positron annihilation measurements reveal micropores in the HCLPS. Especially, the existence of ultramicropores with a size in the range of 0.63-0.7 nm is confirmed by positron lifetime measurements. With increasing DVB content from 0 to 10%, the number of ultramicropores shows a gradual increase. Both the H2 and CO2 adsorption capacity increase monotonously with the increase of the DVB content. With 10% DVB in the HCLPS, the H2 storage increases to 10.3 mmol g-1 (2.05 wt%) at 77 K and 1 bar and the CO2 capture reaches 2.81 mmol g-1 (12.4 wt%) at 273 K and 1 bar. The remarkable gas storage ability is ascribed to the existence of the ultramicropores, which result in a stronger affinity to the gas molecules. By using positrons as a new probe for the pores, our results provide convincing evidence of the role of ultramicropores in the gas adsorption performance in microporous organic polymers.

Microporous polyimide VOC-rejective membrane for the separation of nitrogen/VOC mixture

The treatment of VOCs (volatile organic compounds) in waste streams is very important. Herein, we propose to use a network microporous polyimide (PI) membrane for the molecular sieving of nitrogen over VOC molecules to control their emission. 2,6,14-triaminotriptycene (Trip) was reacted with aromatic dianhydride monomers, such as 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), to synthesize ultramicroporous polyimides, which readily form composite membranes via solution coating. The properties of the PIs were characterized by X-ray photoelectron spectroscopy (XPS), Brunner-Emmet-Teller (BET) analysis, etc., which validated the formation of a network structure and ultramicroporosity in these polyimides. Therefore, the outstanding separation performance for the separation of nitrogen over VOCs, such as cyclohexane, by molecular sieving was obtained by using these membranes; a rejection higher than 99 % was realized with a permeability of approximately 2000∼2600 Barrer under a temperature of 25 °C and feed concentration of 30,000 ± 2000 ppm. Finally, the stability of the Trip-BTDA-PI membrane over time was studied.

Current Research Trends and Perspectives on Solid-State Nanomaterials in Hydrogen Storage

Hydrogen energy, with environment amicable, renewable, efficiency, and cost-effective advantages, is the future mainstream substitution of fossil-based fuel. However, the extremely low volumetric density gives rise to the main challenge in hydrogen storage, and therefore, exploring effective storage techniques is key hurdles that need to be crossed to accomplish the sustainable hydrogen economy. Hydrogen physically or chemically stored into nanomaterials in the solid-state is a desirable prospect for effective large-scale hydrogen storage, which has exhibited great potentials for applications in both reversible onboard storage and regenerable off-board storage applications. Its attractive points include safe, compact, light, reversibility, and efficiently produce sufficient pure hydrogen fuel under the mild condition. This review comprehensively gathers the state-of-art solid-state hydrogen storage technologies using nanostructured materials, involving nanoporous carbon materials, metal-organic frameworks, covalent organic frameworks, porous aromatic frameworks, nanoporous organic polymers, and nanoscale hydrides. It describes significant advances achieved so far, and main barriers need to be surmounted to approach practical applications, as well as offers a perspective for sustainable energy research.

Synthesis methods of microporous organic polymeric adsorbents: a review

MOPs can be synthesized in a large variety of ways, which affect their pores and surface area. Variation in synthesis and porosity has a significant effect on their adsorption properties.

Novel rapid room temperature synthesis of conjugated microporous polymer for metal-free photocatalytic degradation of fluoroquinolones

The existence of Fluoroquinolones (FQs), non-biodegradable pharmacophores, in the natural environment possesses a serious threat. We herein report a novel, rapid, room-temperature synthesis of semiconducting conjugated microporous polymer (CMP) for the decontamination of four second-generation FQs, Norfloxacin, Enrofloxacin, Ciprofloxacin, and Ofloxacin. The CMP demonstrated impressive gas uptake and FQ adsorption ability. Decreased HOMO-LUMO bandgap resulted in enhanced exciton pair generation on visible-light-illumination. Additionally, a high degree of photocurrent response and suitable redox potentials of the material conjointly endorsed its almost quantitative FQ-degradation efficiency. Ofloxacin showed the best removal efficiency with 0.061 and 0.207 min^-1 adsorption and degradation rate constants, respectively, one of the highest values reported. The CMP exhibited equipotent activity for other FQs as well. On increasing the concentration of the FQs or decreasing the incident photo-intensity, quantitative removal efficiencies are observed. Changing the pH of the medium from acidic to alkaline did not impart any change in catalytic activity as well. The reactive species involved viz. O₂^-, ¹O₂, etc. and their roles in the degradation process were determined through control and trapping experiments. A plausible in-depth mechanistic pathway was assessed from the FQ degradation intermediates, and the reactive catalytic species substantiating step-by-step break down of the antibiotic backbone.

Finely Tuned Submicroporous Thin-Film Molecular Sieve Membranes for Highly Efficient Fluid Separations

Polymeric membranes with increasingly high permselective performances are gaining a significant role in lowering the energy burden and improving the environmental sustainability of complex chemical separations. However, the commercial deployment of newly designed materials with promising intrinsic properties for fluid separations has been stalled by challenges associated with fabrication and scale up of low-cost, high-performance, defect-free thin-film composite (TFC) membranes. Here, a facile method to fabricate next-generation TFC membranes using a bridged-bicyclic triptycene tetra-acyl chloride (Trip) building block with a large fraction of finely tuned structural submicroporosity (pore size < 4 Å) is demonstrated. The TFCs exhibit superb potential for removal of small (≈200 g mol^-1 ) organic microcontaminants from organic solvent streams by showing both improved rejection and permeance in organic systems compared to current state-of-the-art commercial membranes. The TFCs also display unprecedented properties for desalination applications with performance located far above the current water permeance/sodium chloride rejection trendline. The strategy of using highly contorted triptycene building blocks with well-defined interconnected internal free volume elements establishes a scalable, generalized approach to fabricate highly selective, submicroporous TFC membranes for a wide variety of challenging energy-intensive fluid separations.

Optimization of the Pore Structures of MOFs for Record High Hydrogen Volumetric Working Capacity

Metal-organic frameworks (MOFs) are promising materials for onboard hydrogen storage thanks to the tunable pore size, pore volume, and pore geometry. In consideration of pore structures, the correlation between the pore volume and hydrogen storage capacity is examined and two empirical equations are rationalized to predict the hydrogen storage capacity of MOFs with different pore geometries. The total hydrogen adsorption under 100 bar and 77 K is predicted as n_tot = 0.085× V_p - 0.013× V_p ² for cage-type MOFs and n_tot = 0.076× V_p - 0.011× V_p ² for channel-type MOFs, where V_p is the pore volume of corresponding MOFs. The predictions by these empirical equations are validated by several MOFs with an average deviation of 5.4%. Compared with a previous equation for activated carbon materials, the empirical equations demonstrate superior accuracy especially for MOFs with high surface area (i.e., S_BET over ≈3000 m² g^-1 ). Guided by these empirical equations, a highly porous Zr-MOF NPF-200 (NPF: Nebraska Porous Framework) is examined to possess outstanding hydrogen total adsorption capacity (65.7 mmol g^-1 ) at 77 K and record high volumetric working capacity of 37.2 g L^-1 between 100 and 5 bar at 77 K.

Stable, Dual Redox Unit Organic Electrodes

The development of organic materials for electrochemical energy storage has attracted great attention because of their high natural abundance and relatively low toxicity. The bulk of these studies focus on small molecules, polymers, or porous/framework-type materials that employ one type of redox moiety. Here, we report the synthesis and testing of organic materials that incorporate two distinct types of redox units: triptycene-based quinones and perylene diimides. We examine this "dual redox" concept through the synthesis of both frameworks and small molecule model compounds with the redox units positioned at the vertices and connection points. Such a design increases the theoretical capacity of the material. It also imparts high stability because both examples are relatively rigid and highly insoluble in the electrolyte. Lithium-ion batteries consisting of the framework and the small molecule have an excellent cycling retention of 75 and 77%, respectively, over 500 cycles at 1 C. Our work emphasizes the advantages of using multiple redox units in the design of the cathodic materials and redox-active triptycene linkages to achieve high cycling stability.

Thermal Cross Linking of Novel Azide Modified Polymers of Intrinsic Microporosity-Effect of Distribution and the Gas Separation Performance

The synthesis of polymers of intrinsic microporosity (PIM) modified with azide groups, the cross linkage by nitrene reaction and their performance as gas separation membranes are reported. The azide modification of the spirobisindane units in the polymer backbone was done by post functionalization of methylated spirobisindane containing polymers. These polymers differ in distribution and concentration of the azide group containing spirobisindane units by applying perfectly alternating and randomly distributed copolymers along the polymer chains. To investigate the influence of concentration of the azide groups, additionally the homopolymer of methylated spirobisindane was synthesized and subjected to identical treatments and characterizations as both copolymers. Cross linkage by nitrene reaction was examined by different temperature treatments at 150, 200, 250 and 300 °C. Characterization of the new polymers was performed by NMR, SEC and FT-IR. Furthermore, the crosslinking process was investigated by means of solid state NMR, TGA-FTIR, DSC and isoconversional kinetic analysis performed with TGA. Gas permeability of CO2, N2, CH4, H2 and O2 was determined by time lag experiments and ideal selectivities for several gas pairs were calculated. The two azide groups per repeating unit degrade during thermal treatments by release of nitrogen and form mechanically stable PIM networks, leading to an increase in gas permeability while selectivity remained nearly constant. Measured diffusivity and solubility coefficients revealed differences in the formation of free volume elements depending on distribution and concentration of the azide groups. Aging studies over about five months were performed and physical aging rates (βP) were evaluated with regard to the concentration and distribution of curable azide functionalities. Subsequently, the enhanced sieving effect during aging resulted in membrane materials that surpassed the Robeson upper bound in selected gas pairs.

Highly Porous Organic Polymers for Hydrogen Fuel Storage

Hydrogen (H2) is one of the best candidates to replace current petroleum energy resources due to its rich abundance and clean combustion. However, the storage of H2 presents a major challenge. There are two methods for storing H2 fuel, chemical and physical, both of which have some advantages and disadvantages. In physical storage, highly porous organic polymers are of particular interest, since they are low cost, easy to scale up, metal-free, and environmentally friendly. In this review, highly porous polymers for H2 fuel storage are examined from five perspectives: (a) brief comparison of H2 storage in highly porous polymers and other storage media; (b) theoretical considerations of the physical storage of H2 molecules in porous polymers; (c) H2 storage in different classes of highly porous organic polymers; (d) characterization of microporosity in these polymers; and (e) future developments for highly porous organic polymers for H2 fuel storage. These topics will provide an introductory overview of highly porous organic polymers in H2 fuel storage.

Porous Polymers as Multifunctional Material Platforms toward Task-Specific Applications

Exploring advanced porous materials is of critical importance in the development of science and technology. Porous polymers, being famous for their all-organic components, tailored pore structures, and adjustable chemical components, have attracted an increasing level of research interest in a large number of applications, including gas adsorption/storage, separation, catalysis, environmental remediation, energy, optoelectronics, and health. Recent years have witnessed tremendous research breakthroughs in these fields thanks to the unique pore structures and versatile skeletons of porous polymers. Here, recent milestones in the diverse applications of porous polymers are presented, with an emphasis on the structural requirements or parameters that dominate their properties and functionalities. The Review covers the following applications: i) gas adsorption, ii) water treatment, iii) separation, iv) heterogeneous catalysis, v) electrochemical energy storage, vi) precursors for porous carbons, and vii) other applications (e.g., intelligent temperature control textiles, sensing, proton conduction, biomedicine, optoelectronics, and actuators). The key requirements for each application are discussed and an in-depth understanding of the structure-property relationships of these advanced materials is provided. Finally, a perspective on the future research directions and challenges in this field is presented for further studies.

Facile synthesis of aminated indole-based porous organic polymer for highly selective capture of CO2 by the coefficient effect of π–π-stacking and hydrogen bonding

A new aromatic aminated indole-based porous organic polymer, PIN-NH₂, has been successfully constructed, and it was demonstrated that the coefficient effect endows this porous material with outstanding CO₂ absorption capacity (27.7 wt%, 1.0 bar, 273 K) and high CO₂/N₂ (137 at 273 K and 1 bar) and CO₂/CH₄ (34 at 273 K and 1 bar) selectivity.

It was demonstrated that the coefficient effect endows POP PIN-NH₂ with outstanding CO₂ absorption capacity and high selectivity.

Aromatic polymers made by reductive polydehalogenation of oligocyclic monomers as conjugated polymers of intrinsic microporosity (C-PIMs)

Incorporation of tetrabenzohepta- or -pentafulvalene connectors into soluble, aromatic polymers results in significantly different optical spectra and intrinsic microporosity.

Membranes with Intrinsic Micro-Porosity: Structure, Solubility, and Applications

Microporous polymer membranes have been widely studied because of their excellent separation performance. Among them, polymers of intrinsic micro-porosity (PIMs) have been regarded as a potential next-generation membrane material for their ultra-permeable characteristics and their solution-processing ability. Therefore, many reviews have been reported on gas separation and monomers for the preparation of PIMs. This review aims to provide an overview of the structure-solubility property. Different structures such as non-network and network macromolecular structure made of different monomers have been reviewed. Then their solubility with different structures and different separation applications such as nanofiltration, pervaporation, and gas/vapor separation are summarized. Lastly, we also provide our perspectives on the challenges and future directions of the microporous polymer membrane for the structure-property relationship, anti-physical aging, and more.