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[Image: see text] Isoreticular chemically stable two-dimensional imine covalent organic frameworks (COFs), further denoted as DUT-175 and DUT-176, are obtained in a reaction of 4,4′-bis(9H-carbazol-9-yl)biphenyl tetraaldehyde with phenyldiamine and benzidine. The crystal structures, solved and refined from the powder X-ray diffraction data and confirmed by high-resolution transmission electron microscopy, indicate AA-stacked layer structures. Both structures feature distorted hexagonal channel pores, assuring remarkable porosity (S(BET) = 1071 m(2) g(–1) for DUT-175 and S(BET) = 1062 m(2) g(–1) for DUT-176), as confirmed by adsorption of gases and vapors. The complex conjugated π system of the COFs involves electron-rich carbazole building units, which in combination with the imine groups allow reversible pH-dependent protonation of the frameworks, accompanied by charge transfer and shift of the absorption bands in the UV–vis spectrum. The sigmoidal shape of the water vapor adsorption and desorption isotherms with a steep adsorption step at p/p(0) = 0.4–0.6 in combination with excellent stability over dozens of adsorption and desorption cycles ranks these COFs among the best materials for indoor humidity control applications.

Flexible metal–organic frameworks (MOFs) are promising materials in gas-related technologies. Adjusting the material to processes requires understanding of the flexibility mechanism and its influence on the adsorption properties. Herein, we present the mechanistic understanding of CO2-induced pore-opening transitions of the water-stable MOF JUK-8 ([Zn(oba)(pip)]n, oba2– = 4,4′-oxybis(benzenedicarboxylate), pip = 4-pyridyl-functionalized benzene-1,3-dicarbohydrazide) as well as its potential applicability in gas purification. Detailed insights into the global structural transformation and subtle local MOF–adsorbate interactions are obtained by three in situ techniques (XRD, IR, and 13CO2-NMR). These results are further supported by single-crystal X-ray diffraction (SC-XRD) analysis of the solvated and guest-free phases. High selectivity toward carbon dioxide derived from the single-gas adsorption experiments of CO2 (195 and 298 K), Ar (84 K), O2 (90 K), N2 (77 K), and CH4 (298 K) is confirmed by high-pressure coadsorption experiments of the CO2/CH4 (75:25 v/v) mixture at different temperatures (288, 293, and 298 K) and in situ NMR studies of the coadsorption of 13CO2/13CH4 (50:50 v/v; 195 K).

Herein we demonstrate mesoporous frameworks interacting with carbon dioxide leading to stimulated structural contractions and massive out‐of‐equilibrium pressure amplification well beyond ambient pressure. Carbon dioxide, a non‐toxic and non‐flammable working medium, is promising for the development of pressure‐amplifying frameworks for pneumatic technologies and safety systems. The strong interaction of the fluid with the framework even contracts DUT‐46, a framework hitherto considered as non‐flexible. Synchrotron‐based in situ PXRD/adsorption experiments reveal the characteristic contraction pressure for DUT‐49 pressure amplification in the range of 350–680 kPa. The stimulated framework contraction expels 1.1 to 2.4 mmol g−1 CO2 leading to autonomous pressure amplification in a pneumatic demonstrator system up to 428 kPa. According to system level estimations even higher theoretical pressure amplification may be achieved between 535 and 1011 kPa., Negative Gas Adsorption is a unique counterintuitive phenomenon of responsive metal–organic frameworks hitherto only observed below atmospheric pressure. Carbon dioxide stimulates contraction at high absolute pressure inducing massive pressure amplification exceeding 500 kPa.

Self-discharge is a spontaneous process taking place in electrochemical double layer capacitors (EDLCs) that might affect their introduction into specific applications. In recent years, several studies investigated the dynamics of the potential decay occurring during the self-discharge of EDLCs, but the impact of diffusion processes on the self-discharge is still not well understood. In order to gain information about this important aspect we carried out a study in which we combined in situ NMR spectroscopy and electrochemical techniques. We found that the diffusion processes taking place at the electrode-electrolyte interphase are not static, as commonly assumed, but dynamically influence the self-discharge of EDLCs. These results suggest that the models describing this spontaneous process should be revised, and the diffusion should not be considered as a static, but as a dynamic process affecting self-discharge of EDLCs.

Metal–organic framework crystal–glass composites (MOF CGCs) have previously been formed by embedding crystalline MIL-53(Al) within a ZIF-62 glass (agZIF-62) matrix. Here we highlight thermal stability considerations in the formation of MOF CGCs, and subsequently report the synthesis of two novel MOF CGCs, by incorporating MIL-118 and UL-MOF-1 within agZIF-62. These new materials, alongside the prototypical MOF CGC, formed using MIL-53(Al), were studied using scanning electron microscopy, powder X-ray diffraction, and gas sorption techniques. The gas uptake in composites formed from MIL-118C and UL-MOF-1 is largely dominated by the agZIF-62 matrix, suggesting that to improve the porosity of the MOF CGC, the matrix porosity must be improved, or a percolation threshold must be overcome.

The existence of correlated disorder in molecular frameworks is an obvious mechanism by which unusual cooperative phenomena might be realised. We show that the use of local-symmetry lowering approaches can allow ostensibly high-symmetry framework structures to harbour exotic disordered states often studied in the context of spin lattice models. These states exhibit strongly cooperative behaviour that might be exploited in anomalous mechanical, host/guest, and information storage behaviour. Our contribution focuses in particular on the concepts of (i) combinatorial mechanics, (ii) adaptive flexibility, and (iii) error-correcting data storage in framework materials.

A combination of soft lithographic printing and soft templating has been used to fabricate high‐resolution interdigitated micro‐supercapacitors (MSC). Surfactant‐assisted self‐assembly produces high surface area ordered mesoporous carbons (490 m2 g−1). For the first time, such precursors have been printed by nano‐imprint lithography as microdevices with a line width of only 250 nm and a spacing of only 1 μm. The devices are crack‐free with low specific resistance (1.2×10−5 Ωm) and show good device capacitance up to 0.21 F cm−3., A fine line: A combination of soft lithographic methods and soft templating was used to fabricate high‐resolution micro‐supercapacitors (MSC). Surfactant‐assisted self‐assembly produces high surface area ordered mesoporous carbons. For the first time, such precursors can be printed by nano‐imprint lithography as microdevices with a line width of only 250 nm and a spacing of only 1 μm.

Room-temperature sodium-sulfur (RT-Na/S) batteries are an important class of rechargeable batteries with a high theoretical capacity of 1675 mAh g-1 and energy density up to 1276 Wh kg-1. Together with the abundant and cheap sodium and sulfur, RT-Na/S batteries are recognized as one of the attractive next-generation high-energy-density devices for large-scale energy storage. However, similar to the working principle in lithium-sulfur batteries, RT-Na/S batteries suffer from some essential problems such as the poor conductivity of elemental sulfur, the large volume change during charge-discharge cycling and the serious shuttle effect caused by sodium polysulfides dissolution. Moreover, the shuttle effect and volume variation seem more pronounced in RT-Na/S batteries, which further deteriorates their performances and seriously hinders the progress towards practical application. Recent years have witnessed a fast growth of designing porous carbons especially hollow carbon spheres (HCSs) as sulfur host to address these problems, due to their unique structural features such as special shape, large void space, permeable shell and facile functionalization. This review summarizes the recent progress of HCSs-based materials as the sulfur hosts in RT-Na/S batteries. Beginning with a brief introduction to RT-Na/S batteries, carbon hosts and design strategies for preparing HCSs, emphasis is then placed on manipulating the pore structure, heteroatom doping and metal species decoration with the aim to alleviate the “shuttle effect” and thus to improve the performance. Finally, perspectives on current challenge and future directions are also discussed.

Porphyrins and porphyrin derivatives have been widely explored for various applications owing to their excellent photophysical and electrochemical properties. However, inherent shortcomings, such as instability and self‐quenching under physiological conditions, limit their biomedical applications. In recent years, metal–organic frameworks (MOFs) have received increasing attention. The construction of porphyrin‐based MOFs by introducing porphyrin molecules into MOFs or using porphyrins as organic linkers to form MOFs can combine the unique features of porphyrins and MOFs as well as overcome the limitations of porphyrins. This Review summarizes important synthesis strategies for porphyrin‐based MOFs including porphyrin@MOFs, porphyrinic MOFs, and composite porphyrinic MOFs, and highlights recent achievements and progress in the development of porphyrin‐based MOFs for biomedical applications in tumor therapy and biosensing. Finally, the challenges and prospects presented by this class of emerging materials for biomedical applications are discussed., Porphyrin‐based metal–organic frameworks can be designed and constructed for powerful biomedical applications. Recent progress and future expectations are discussed in this Review.

Rational manipulation of the carbon framework from the microporous to nonporous via a molecular design approach is interesting but challenging. Herein, we report a versatile strategy for transforming the microporous carbon framework to the low porous one by an elaborate molecular crosslinker design in the polystyrene (PS) precursor. Direct coupling of benzene rings in PS via Scholl reaction yields hypercrosslinked PS-derived carbon with low porous framework, while insertion of methylene crosslinker into PS via a solvent knitting strategy leads to microporous carbon framework. The results show that methylene crosslinker functions as molecular-scale soft templates for facilitating micropores, whereas direct linking PS chains promotes aromatization and mitigates micropore formation during the pyrolysis. The distinct carbon frameworks derived from similar precursor and pyrolysis condition provide an intriguing platform for structure-property relationship study, as preliminarily exemplified by the application in Na ion storage. The low-porosity carbon shows higher initial Coulombic efficiency and superior capacity thanks to its low surface area and enhanced Na insertion into pseudo-graphitic microcrystal structure. The present protocol opens up new avenues towards flexible carbon framework porosity manipulation at molecular level and would trigger further efforts for low-porosity carbons in energy storage.

Lithium-ion battery has greatly changed our lifestyle and the solid electrolyte interphase (SEI) covered on the graphite anode determines the service life of a battery. The formation method and the formation temperature at initial cycle of a battery determine the feature of the SEI. Herein, we investigate the gap of formation behavior in both a half cell (graphite matches with lithium anode) and a full cell (graphite matches with NCM, short for LiNixCoyMn1−x−yO2) at different temperatures. We conclude that high temperature causes severe side reactions and low temperature will result in low ionic conductive SEI layer, the interface formed at room temperature owns the best ionic conductivity and stability.

Four new layered flexible metal–organic frameworks (MOFs) containing a diacylhydrazone moiety, namely, guest-filled [Zn2(iso)2(tdih)2]n (1), [Zn2(NH2iso)2(tdih)2]n (2), [Cd2(iso)2(tdih)2]n (3) and ...

The origin of crystal-size-dependent adsorption behavior of flexible metal-organic frameworks is increasingly studied. In this contribution, we probe the solid-fluid interactions of DUT-49 crystals of different size by in situ 129Xe NMR spectroscopy at 200 K. With decreasing size of the crystals, the average solid-fluid interactions are found to decrease reflected by a decrease in chemical shift of adsorbed xenon from 230 to 200 ppm, explaining the lack of adsorption-induced transitions for smaller crystals. However, recent studies propose that these results can also originate from the presence of lattice defects. To investigate the influence of defects on the adsorption behavior of DUT-49, we synthesized a series of samples with tailored defect concentrations and characterized them by in situ 129Xe NMR. In comparison to the results obtained for crystals with different size, we find pronounced changes of the adsorption behavior and influence of the chemical shift only for very high concentrations of defects, which further emphasizes the important role of particle size phenomena.

The development of ultrastable carbon materials for potassium storage poses key limitations caused by the huge volume variation and sluggish kinetics. Nitrogen‐enriched porous carbons have recently emerged as promising candidates for this application; however, rational control over nitrogen doping is needed to further suppress the long‐term capacity fading. Here we propose a strategy based on pyrolysis–etching of a pyridine‐coordinated polymer for deliberate manipulation of edge‐nitrogen doping and specific spatial distribution in amorphous high‐surface‐area carbons; the obtained material shows an edge‐nitrogen content of up to 9.34 at %, richer N distribution inside the material, and high surface area of 616 m2 g−1 under a cost‐effective low‐temperature carbonization. The optimized carbon delivers unprecedented K‐storage stability over 6000 cycles with negligible capacity decay (252 mA h g−1 after 4 months at 1 A g−1), rarely reported for potassium storage., Pyrolysis–etching of a pyridine‐coordinated polymer was used to prepare a porous carbon material with defect edge‐enriched N‐6/N‐5 doping, high surface area, and rich distribution of N defects within the material. This carbonaceous material allows full utilization of surface‐dominated capacitive K storage with ultrastable cycling.

A novel chiral diimine Zr-MOF (DUT-136, DUT - Dresden University of Technology) is synthesized in a one-pot reaction from ZrCl4, 4-formylbenzoic acid, and (R,R)-1,2-diphenylethylenediamine as an enantiopure core. Inspired by the versatile chemistry of the C N bond, a variety of post-synthetic derivatizations were performed. Oxidation, reduction, and metalation effectively generated the chiral amide-, amine-, and Ni containing DUT-136 MOFs, respectively. The catalytic activity of these post-synthetically modified materials was systemically evaluated in a wide range of asymmetric organic transformations, including the Friedel-Crafts alkylation, Michael addition, aldol reaction, and the Ni-catalyzed C C coupling.

Controlling the adsorption behavior of switchable porous materials is essential to pave the way for their successful implementation in highly selective separation and sensing applications. The swit...

Lithium-sulfur (Li–S) batteries are among the targeted candidates for future generation secondary batteries with high specific energy. Herein, a scalable synthesis is presented to produce highly porous, nitrogen-doped carbons from a commercial carbon black material by melamine impregnation and subsequent thermolysis. The process up-scaling up was demonstrated at > 100 g batch level. The nitrogen doping was controlled through pyrolysis temperatures and carbon to melamine ratio. The sulfur-carbon cathodes exhibit an enhanced cycle life at a moderate electrolyte to sulfur ratio of 7 μL mgS−1. In particular, under lean conditions at low electrolyte amount of 5 μL mgS−1, the nitrogen functionalities improved active material utilization and capacity retention significantly. The nitrogen-doped scaffold was integrated into five-layered prototype cell (71 × 46 mm2) with a capacity of up to 0.87 Ah reaching a specific energy density of 238 Wh kg−1 on stack level. These results provide new insights into realistic application of nitrogen-doped carbons on pouch cell level.

Rationally tuning frameworks of porous carbons from the microporous to nonporous is still a challenge on a given precursor and carbonization condition. Here a simple yet general mechanical-assisted route is reported for the conversion of a microporous carbon framework into the nonporous one through applying the mechanical pressure on the precursor prior to carbonization, which generates microporous-free and low-defect carbon frameworks. While direct carbonization without pressure treatment produces microporous carbon framework under the same carbonization conditions. The results show that pressure treatment helps to retard the deprotonation and the cross-linking process while facilitating the chain scission and aromatization, thus creating more order-layered graphitic nanodomains without substantial micropores. Such a distinct framework microstructure enables the resulting carbons to exhibit advantages in task-specific energy storage applications. For example, the microporous-free carbon with low defect in microcrystallites achieves superior Na ion storage capacity, higher rate performance and unprecedented long-term cycle stability; while the carbon with microporous framework and high surface area facilitates the formation of the electrical double layer for higher capacitances in supercapacitors. Our results clearly show the facile manipulation of carbon framework from the microporous to the low-porous and their important structural aspect for task-specific electrochemical applications.

Solid-state electrolytes (SSEs) are widely considered as an “enabler” to inhibit dendrite growth of lithium-metal anodes for high-energy and highly safe next-generation batteries. However, recent s...

Lithium metal anodes are among the most promising candidates for further increasing the energy density of lithium ion batteries and all-solid-state batteries. A reduction of the anode thickness by using ultrathin lithium metal films is a crucial requirement to achieve a significant overall reduction of thickness on cell level. However, besides anode stabilization, realizing scalable technologies for an efficient production of thin lithium metal anodes is one of the most challenging obstacles for the success of various next-generation battery chemistries. In this publication we introduce a disruptive lithium melt deposition process for thin lithium metal coating on thin copper current collector foils. The wetting of molten lithium on the substrate can only be achieved through a lithiophilic interlayer. As a result fast and homogeneous lithium spreading on the substrate is enabled allowing roll-to-roll coating with liquid-deposition technologies as demonstrated in this contribution with a speed of several meters per minute and reaching 100 mm width. With this new process the anode thickness can be tuned in a wide range (1 - 30 µm). Evaluation in a prototype solid battery system shows high electrochemical lithium utilization and no detrimental effects compared to commercially available lithium reference foils.

We present a toolbox for the rapid characterisation of powdered samples of paramagnetic metal–organic frameworks at natural abundance by 1H‐detected solid‐state NMR. Very fast MAS rates at room and cryogenic temperatures and a set of tailored radiofrequency irradiation schemes help overcome the sensitivity and resolution limits often associated with the characterisation of MOF materials. We demonstrate the approach on DUT‐8(Ni), a framework containing Ni2+ paddle‐wheel units which can exist in two markedly different architectures. Resolved 1H and 13C resonances of organic linkers are detected and assigned in few hours with only 1–2 mg of sample at natural isotopic abundance, and used to rapidly extract information on structure and local internal dynamics of the assemblies, as well as to elucidate the metal electronic properties over an extended temperature range. The experiments disclose new possibilities for describing local and global structural changes and correlating them to electronic and magnetic properties of the assemblies., Paramagnetic DUT‐8(Ni) metal–organic frameworks were characterised over an extended temperature range with 1H‐detected NMR techniques under fast magic‐angle spinning. The sensitivity of the approach allows rapid access to structure and dynamics of the organic linkers as well as the electronic properties of the metal centres in these materials.

We evaluate experimentally the force exerted by flexible metal-organic frameworks through expansion for a representative model system, namely MIL-53(Al). The results obtained are compared with data collected from intrusion experiments while molecular simulations are performed to shed light on the re-opening of the guest-loaded structure. The critical impact of the transition stimulating medium on the magnitude of the expansion force is demonstrated.

BiVO4 nanoparticles with tailored sizes and rich oxygen vacancies were facilely synthesized via pulsed laser irradiation of colloidal nanoparticles (PLICN). As anode materials for Na-ion batteries, the revolutionized sodium storage process found in sub-10 nm BiVO4 nanocrystals results in outstanding properties including extraordinary rate capability and remarkable cycling stability.

In situ formation of imine-based organic linkers facilitates the formation of metal–organic frameworks (MOFs), in particular if linker solubility hampers the direct synthesis. The reaction of ZrCl4...

A 20-A-long diacylhydrazone linker was used for the first time as a building block for the construction of a metal–organic framework (MOF). The terephthalaldehyde di-isonicotinoylhydrazone (tdih) i...

A chiral zirconium-based catalyst, DUT-67-Pro containing 8-connected Zr6-clusters is obtained by post synthetic functionalization of Zr6O6(OH)2(TDC)4(HCOO)2 (DUT-67, TDC = 2,5-thiophenedicarboxylate) with the chiral monocarboxylic acid, L -proline. 13C and 15N solid state MAS and DNP NMR studies of DUT-67-Pro confirm the integration of L -proline into the porous framework. The chiral MOF catalyst exhibits an excellent catalytic activity at low temperature (298 K) with an unprecedented syn-(S,S)-product selectivity in an asymmetric aldol addition reaction of cyclohexanone to 4-nitrobenzaldehyde (yield = 95%, ee = 96%). Comparative catalytic studies using a molecular Zr6-cluster model compound indicate the Zr6-moiety to be responsible for this inverse diastereoselectivity compared to well-established L -proline organocatalysis and a mechanism is proposed to explain the Zr6-cluster-mediated syn-selectivity. Masking residual acidic active sites in the cluster of the framework was found to be a key prerequisite to achieve the high enantioselectivity. The purely heterogeneous catalytic system based on DUT-67-Pro is highly stable and can be recycled several times.

All-solid-state lithium-ion batteries are promising candidates to overcome safety and energy limitations of common lithium-ion batteries. Although excellent results have been reported for sulfide based electrolytes on a small scale, classical slurry-based lithium-ion processing fails to reproduce the same performance in a larger cell. In this study, a dry-film (DF) process is presented that replaces slurry based binders by a fibrous PTFE binder and reduces the binder amount to an absolute minimum as low as 0.1 wt%, which is the lowest reported value so far. Free-standing NCM sheets with a high areal loading of 6.5 mAh cm−2 were prepared showing even at room temperature the same rate performance like binder-free electrodes with 2.5 mAh cm−2. The impact of binder content on cell performance has been studied revealing significantly reduced impedance at contents below 0.7 wt%. To realize a practical cell, the cell composition was optimized and a 9 cm2 sized rocking-chair type all-solid-state battery was prepared without any solvents underlining the sustainability of the DF process. The battery was cycled for 100 cycles without any artificial pressure, demonstrating the versatility and potential of the DF process.

The successful transfer of room temperature sodium sulfur (RT-Na-S) technology from coin cell to pouch cell level is demonstrated. The general cell design is based on a previously developed RT-Na-S concept implementing hard carbon based anodes. Scalable technologies known from lithium ion battery production are utilized for electrode production. The electrolyte composition, the voltage window as well as the balancing is evaluated on coin cell level leading to optimized parameters. For scaled electrodes and electrolytes, a specific capacity of 418 mAh gS−1 coupled with a high coulombic efficiency of 95.3% can be still obtained in RT-Na-S coin cells after a total of 549 cycles. Residual carbonates in the HC-anode were found to deteriorate the cycling performance. An increased cut-off voltage (1.5 V) significantly raises the coulombic efficiency. Finally, the design is successfully transferred to a 10-layered pouch cell leading to a high energy efficiency of 88.6% and a capacity of 387 mAh gS−1 after a total of 937 cycles. Hence, the present work shows the principle feasibility of a stationary energy storage technology based on RT-Na-S pouch cell technology.

Selective C-13-labelling of carboxylate carbons in the linker molecules of flexible metal-organic frameworks (MOFs) makes solid-state NMR spectroscopy very powerful to investigate solvent-induced local structural changes as demonstrated by C-13 and H-1 NMR spectroscopy on the pillared layer MOF DUT-8(Ni). Selective identification of polar solvent-node interactions becomes feasible.

Heteroatom functionalization of ordered mesoporous carbon (OMC) represents an important strategy towards electrocatalytic and battery applications. Such functionalization frequently leads to degradation or even collapse of mesopores, which is generally attributed to the harsh conditions used or the successfully doped functional groups or the entrapment of guest species into mesopores. However, in this report, we find the structural deterioration of functionalized OMC is mainly induced by the water evaporation during the drying process, beyond the usually accepted concept mentioned above. We report two types of well-defined OMCs, resembling comparable pore architectures but varying in surface chemistry, namely the hydrophobic OMC (Cmeso) and hydrophilic one (HCmeso). After washing and drying processes, Cmeso remains intact regardless of the drying processes. In sharp contrast, HCmeso shows gradual porosity deterioration or even totally collapse under continuous washing-drying cycles. Lyophilization can however well preserve the porosity due to the reduced stress exerted by water on carbon walls. Such a distinct phenomenon is elaborately characterized by N2 physisorption, H2O physisorption, TEM and SAXS and further validated by well-known CMK-3, which undergoes surface functionalization by concentrated HNO3. Our finding reveals an important but neglected issue addressing the drying process in particular for polar functionalized porous carbons.

Bioactive peptides, such as isoleucyl-tryptophan (IW), exhibit a high potential to inhibit the angiotensin-converting enzyme (ACE). Adsorption on carbon materials provides a beneficial method to extract these specific molecules from the complex mixture of an alpha-lactalbumin hydrolysate. This study focuses on the impact of nitrogen functionalization of porous carbon adsorbents, either via pre- or post-treatment, on the adsorption behavior of the ACE-inhibiting peptide IW and the essential amino acid tryptophan (W). The commercially activated carbon Norit ROX 0.8 is compared with pre- and postsynthetically functionalized N-doped carbon in terms of surface area, pore size, and surface functionality. For prefunctionalization, a covalent triazine framework was synthesized by trimerization of an aromatic nitrile under ionothermal conditions. For the postsynthetic approach, the activated carbon ROX 0.8 was functionalized with the nitrogen-rich molecule melamine. The batch adsorption results using model mixtures containing the single components IW and W could be transferred to a more complex mixture of an alpha-lactalbumin hydrolysate containing a huge number of various peptides. For this purpose, reverse-phase high-pressure liquid chromatography with fluorescence detection was used for identification and quantification. The treatment with the three different carbon materials leads to an increase in the ACE-inhibiting effect in vitro. The modified surface structure of the carbon via pre- or post-treatment allows separation of IW and W due to the certain selectivity for either the amino acid or the dipeptide.

Layered two-dimensional (2D) conjugated metal-organic frameworks (MOFs) represent a family of rising electrocatalysts for the oxygen reduction reaction (ORR), due to the controllable architectures, excellent electrical conductivity, and highly exposed well-defined molecular active sites. Herein, we report a copper phthalocyanine based 2D conjugated MOF with square-planar cobalt bis(dihydroxy) complexes (Co-O4 ) as linkages (PcCu-O8 -Co) and layer-stacked structures prepared via solvothermal synthesis. PcCu-O8 -Co 2D MOF mixed with carbon nanotubes exhibits excellent electrocatalytic ORR activity (E1/2 =0.83 V vs. RHE, n=3.93, and jL =5.3 mA cm-2 ) in alkaline media, which is the record value among the reported intrinsic MOF electrocatalysts. Supported by in situ Raman spectro-electrochemistry and theoretical modeling as well as contrast catalytic tests, we identified the cobalt nodes as ORR active sites. Furthermore, when employed as a cathode electrocatalyst for zinc-air batteries, PcCu-O8 -Co delivers a maximum power density of 94 mW cm-2 , outperforming the state-of-the-art Pt/C electrocatalysts (78.3 mW cm-2 ).

Hierarchical yet densely packed porous carbon electrodes are vital for achieving high-performance capacitive energy storage. However, hierarchical porous carbons (HPCs) suffer from a trade-off in terms of meso- and macroporosity ratio related to the pore size dependent diffusive ion mobility versus the material density dominating the volumetric performance. Here we report an interesting insight into a balanced effect of meso- and macroporosity ratio and the material density with a practical high mass loading by designing HPCs with controlled meso- and macroporosity ratio. This is achieved via a hypercrosslinking strategy of polystyrene without the assistant of any templates or activation. It is found that ion transport rates increase along with increasing the meso- and macropore content to 26% and then gradually level off even further increasing the amount to 73%. An appropriate meso- and macropore content without sacrificing the ion diffusivity is beneficial for achieving effective material densities up to 0.76 g cm−3, leading to superior volumetric capacitances, as compared with those showing either lower or higher meso- and macropore content. This study clearly highlights the need for fine-tuning the pore ratios at different scales in hierarchical structures to achieve high-performance applications for practical applications.

The transition metal halide α-titanium(III) chloride (α-TiCl3) is a layered two-dimensional compound and a well-established Ziegler–Natta catalyst for the polymerization of ethylene. A new synthesi...

Highly selective electrooxidation catalysts were synthesized by functionalizing a commercially available reference electrooxidation catalyst (Pt/Vulcan XC 72R) with a coating of the highly hydrophobic porous zeolitic imidazolate framework ZIF-8, an adsorbent with high affinity for the extraction of aliphatic alcohols from water. According to cyclovoltammetric studies in alkaline media at 25 °C, the ZIF-8 functionalized catalyst shows a high selectivity for the electrooxidation of small alcohols such as ethanol and methanol over more hydrophobic alcohols ( n-butanol, n-propanol). In contrast, the noncoated reference catalyst (Pt/Vulcan XC 72R) oxidizes all investigated alcohols with comparable current densities. Tafel curves confirm these observations and indicate a limited conversion of long chain alcohols, especially n-butanol, caused by the high affinity of the ZIF-8 for this molecule resulting in significant diffusion limitations.

The interactions between two selected porous carbon materials and ionic-liquid based electrolyte solutions consisting of the ionic liquid 1-Ethyl-3-methylimidazolium tetrafluoroborate (EmimBF4) diluted with acetonitrile are investigated within the present paper by combined use of cyclic voltammetry, electrochemical impedance spectroscopy, and NMR spectroscopy. The commercially available microporous YP50F and the hierarchically organized micro- and mesoporous OM-CDC (ordered mesoporous carbide derived carbon) are selected as model materials to achieve a better understanding of the electrolyte behavior, especially its mobility, in porous carbons. The ionic liquid chosen as electrolyte leads to high specific capacitance approaching 180 F g-1 for OM-CDC. Due to the hierarchical pore system, OM-CDC shows a better rate performance than YP50F. NMR analyses provide an understanding of the molecular processes giving rise to the above-mentioned observations. They reveal a limited accessibility of the narrow pores in YP50F for pure EmimBF4 in contrast to OM-CDC. It was found that about 30% of the entire pore volume of YP50F remain unfilled by electrolyte ions without dilution. Dilution with acetonitrile significantly increased the anion mobility as the NMR signal of adsorbed ions becomes narrower. A mixture containing 60% EmimBF4 and 40% acetonitrile was identified as the optimum for electrochemical applications.

Optical calorimetry (broadband IR-detection of the released heat of adsorption, “InfraSORP”) during water adsorption processes is used for an accelerated assessment of porous materials performance in heat pump applications. Metal-organic frameworks (MOFs) are screened as a highly promising class of materials for water adsorption driven heat exchangers with high water adsorption capacities. Based on a proper calibration, optical calorimetry is demonstrated to allow for rapid estimation of the total water adsorption capacity at a given relative humidity. In a dynamic mode, full water adsorption isotherms can be measured using a step-wise increase of the relative humidity. As cycling stability is among the most critical issues for the integration of new porous materials into systems, the InfraSORP methodology provides a valuable and inexpensive tool for accelerated cycling and stability testing. The InfraSORP technique is demonstrated to provide a significantly accelerated automated and easy-to-acquire alternative as compared to conventional characterization methods.

A Cu2+-doped metal–organic framework (DUT-8(Ni0.98Cu0.02), M2(NDC)2DABCO, M = Ni, Cu, NDC = 2,6-napththalene dicarboxylate, DABCO = 1,4-diazabicyclo[2.2.2]octane, DUT = Dresden University of Technology) was synthesized in the form of large (>1 μm) and small crystals (

Metal–organic frameworks (MOFs) are constructed from a combination of inorganic and organic units to produce materials which display high porosity, among other unique and exciting properties. MOFs have shown promise in many wide ranging applications, such as catalysis and gas separations. In this review, we highlight MOF research conducted by Germany-based research groups. Specifically, we feature approaches for the synthesis of new MOFs, high-throughput MOF production, advanced characterization methods and examples of advanced functions and properties.:1. Introduction 2. Chemistry and materials 3. Towards an industrial scale 4. Advanced characterization 5. Advanced function 6. Conclusion Acknowledgements References

Herein we compare various preparation methods for thin ZIF-8 layers on a Cu substrate for application as a host material for omniphobic lubricant-infused surfaces. Such omniphobic surfaces can be used in thermal engineering applications, for example to achieve dropwise condensation or anti-fouling and anti-icing surface properties. For these applications, a thin, conformal, homogeneous, mechanically and chemically stable coating is essential. In this study, thin ZIF-8 layers were deposited on a Cu substrate by different routes, such as (i) electrochemical anodic deposition on a Zn-covered Cu substrate, (ii) doctor blade technique for preparation of a composite layer containing PVDF binder and ZIF-8, as well as (iii) doctor blade technique for preparation of a two-layer composite on the Cu substrate containing a PVDF-film and a ZIF-8 layer. The morphology and topography of the coatings were compared by using profilometry, XRD, SEM and TEM techniques. After infusion with a perfluorinated oil, the wettability of the surfaces was assessed by contact angle measurements, and advantages of each preparation method were discussed.

New nanoporous materials are able to revolutionize adsorption and separation processes. In particular, materials with adaptive cavities have high selectivity and may display previously undiscovered phenomena, such as negative gas adsorption (NGA), in which gas is released from the framework upon an increase in pressure. Although the thermodynamic driving force behind this and many other counterintuitive adsorption phenomena have been thoroughly investigated in recent years, several experimental observations remain difficult to explain. This necessitates a comprehensive analysis of gas adsorption akin to the conformational free energy landscapes used to understand the function of proteins. For the first time, we constructed the complete thermodynamic landscape of methane adsorption on DUT-49, a system that demonstrates NGA. Traversing this complex landscape correctly reproduces the experimentally observed structural transitions, the temperature dependence of the NGA phenomenon and the observed hysteresis between adsorption and desorption. The complete thermodynamic description presented here provides unparalleled insight into the process of adsorption and provides a framework to understand other adsorbents that challenge our preconceptions.

The ultrahigh porosity and varied functionalities of porous metal–organic frameworks make them excellent candidates for applications that range widely from gas storage and separation to catalysis and sensing. An interesting feature of some frameworks is the ability to open their pores to a specific guest, enabling highly selective separation. A prerequisite for this is bistability of the host structure, which enables the framework to breathe, that is, to switch between two stability minima in response to its environment. Here we describe a porous framework DUT-8(Ni)—which consists of nickel paddle wheel clusters and carboxylate linkers—that adopts a configurationally degenerate family of disordered states in the presence of specific guests. This disorder originates from the nonlinear linkers arranging the clusters in closed loops of different local symmetries that in turn propagate as complex tilings. Solvent exchange stimulates the formation of distinct disordered frameworks, as demonstrated by high-resolution transmission electron microscopy and diffraction techniques. Guest exchange was shown to stimulate repeatable switching transitions between distinct disorder states. Some flexible metal–organic frameworks are known to exhibit an adaptive behaviour as they convert between two stable forms in response to their environment. Now, a metal–organic framework based on nonlinear linkers has been shown to adopt a much more complex family of degenerate disordered configurations, which can be reversibly interconverted through guest exchange.

The switching mechanism of the flexible framework Zn4O(benztb)1.5 (benztb=N,N,N’,N’‐benzidine tetrabenzoate), also known as DUT‐13, was studied by advanced powder X‐ray diffraction (PXRD) and gas physisorption techniques. In situ synchrotron PXRD experiments upon physisorption of nitrogen (77 K) and n‐butane (273 K) shed light on the hitherto unnoticed guest‐induced breathing in the MOF. The mechanism of contraction is based on the conformationally labile benztb ligand and accompanied by a reduction in specific pore volume from 2.03 cm3 g−1 in the open‐pore phase to 0.91 cm3 g−1 in the contracted‐pore phase. The high temperature limit for adsorption‐induced contraction of 170 K, determined by systematic temperature variation of methane adsorption isotherms, indicates that the DUT‐13 framework is softer than other mesoporous MOFs like DUT‐49 and does not support the formation of overloaded metastable states required for negative gas‐adsorption transitions., Breathe! Combining synchrotron in situ PXRD with gas adsorption has shed light on the mechanism of guest‐induced breathing in dynamic DUT‐13 framework. In the contracted‐pore phase, the crystal has pores half the volume of those in the open‐pore phase; this is consistent with the adsorption isotherms. Methane physisorption isotherms at different temperatures indicate the softness of the framework.

New advanced adsorbents are a crucial driver for the development of energy and environmental applications. Tremendous potential is provided by machine learning and data mining techniques, as these approaches can identify the most appropriate adsorbent for a particular application. However, the current scientific reporting of adsorption isotherms in graphs and figures is not adequate to reproduce original experimentally measured data.This report proposes the specification of a new standard adsorption information file (AIF) inspired by the ubiquitous crystallographic information file (CIF) and based on the self-defining text archive and retrieval (STAR) procedure, also used to represent biological nuclear magnetic resonance experiments (NMR-STAR). The AIF is a flexible and easily extended free-format archive file that is readily human and machine readableand is simple to edit using a basic text editor or parse for database curation. This format represents the first steps toward an open adsorption data format as a basis for a decentralized adsorption data library.An open format facilitates the electronic transmission of adsorption data between laboratories, journals and larger databases, which is key in the effort to increase open science in the field of porous materials in the future.

Linker elongation is an important method to systematically adjust porosity and pore size in isoreticular MOFs. In flexible structures, this approach opens the possibility for the systematic analysis of the building blocks and their contribution to the overall flexible behavior enabling tuning of the framework responsivity toward molecular stimuli. In this work, we report two new compounds isoreticular to the highly flexible pillared layer structure DUT-8(Ni) ([Ni2(2,6-ndc)2(dabco)]n, 2,6-ndc = 2,6-naphthalenedicarboxylate, dabco = 1,4-diazabicylo[2.2.2]octane). Aromatic linker 2,6-ndc was substituted by longer carboxylic linkers, namely, 4,4'-biphenyldicarboxylate (4,4'-bpdc) and 4,4'-stilbenedicarboxylate (4,4'-sdc), while the dabco pillar was retained. The structural response of the new compounds toward the desolvation and adsorption of various fluids was studied using advanced in situ PXRD techniques, demonstrating distinct differences in the flexible behavior of three compounds and disclosing the impact of linker structure on the framework response. Theoretical calculations provide mechanistic insights and an energetic rationale for the pronounced differences in switchability observed. The energetics of linker bending and linker-linker dispersion interactions govern the phase transitions in investigated MOFs.

The flexibility of soft porous crystals, i.e., their ability to respond to external stimuli with structural changes, is one of the most fascinating features of metal-organic frameworks. In addition to breathing and swelling phenomena of flexible MOFs, negative gas adsorption and pressure amplification is one of the more recent discoveries in this field, initially observed in the cubic DUT-49 framework. In recent years the structural contraction was monitored by physisorption, X‑ray diffraction, NMR and EPR techniques, providing only limited information about the electronic structure of the ligand. In this work we designed a new ligand with a fluorescent core in the linker backbone and synthesized three new MOFs, isoreticular to DUT-49, denoted as DUT‑140(M) (M - Cu, Co, Zn) crystalizing in space group. DUT‑140(Cu) can be desolvated and is highly porous with an accessible apparent surface area of 4870 m2g-1 and a pore volume of 2.59 cm3g-1. Furthermore, it shows flexibility and NGA upon adsorption of subcritical gases. DUT-140(Zn), synthesized using post-synthetic metal exchange, could only be studied with guests in the pores. In addition to the investigation of the adsorption behavior of DUT-140(Cu) spectroscopic and computational methods were used to study the light absorption properties.

Crystal growth & design 21(1), 270–276 (2021). doi:10.1021/acs.cgd.0c01080, Removal of the guest molecules from the pores of metal–organic frameworks (MOFs) is one of the critical steps in particular for highly porous frameworks associated with high internal stress. In the case of isostructural mesoporous DUT-49(M) (M = Cu, Ni, Mn, Fe, Co, Zn, Cd) frameworks, only DUT-49(Cu) and DUT-49(Ni) could be successfully desolvated so far and only by using supercritical activation. To get a deeper insight into the processes occurring upon the desorption of the solvent from the pores of DUT-49(M), the desolvation was monitored in situ by synchrotron powder X-ray diffraction (PXRD). Analysis of the time-resolved PXRD data shows the full structural transformation pathway of the solid, which involves continuous and discontinuous phase transitions from the open pore (op) to the intermediate pore (ip) phase and from the ip to the contracted pore (cp) phase for DUT-49(Cu) and DUT-49(Ni). For DUT-49(Zn), the op to ip transition is directly followed by amorphization of the framework. All other frameworks show direct amorphization of the op phase., Published by ACS Publ., Washington, DC

The growing need for renewable energies requires the development of efficient energy storage technologies such as supercapacitors. Using aqueous electrolytes, usually high ion concentrations are required to generate high capacitances and power densities. Herein, we report an anomalous electrochemical charge storage behavior of supercapacitors in a very diluted electrolyte and even pure water, enabled by a densely N- and O-doped ultra-hydrophilic carbon (DUT-108). Minimizing the electrolyte concentration from 1 down to 0.001 M, the capacitance of DUT-108 only decreases from 192 to 147 F/g; while a commercially available model carbon (ROX) decreases considerably in capacitances (i.e., 90 to 32 F/g). More interestingly, when using water, DUT-108 still reaches 137 F/g in contrast to hydrophobic ROX (27 F/g). Impedance analysis further confirms low resistance change by showing a significantly higher ion diffusion ability of charge carriers within DUT-108. We hypothesize that this phenomenon could be driven by proton hopping on the amphoteric N- and O-groups and the abrupt passing of protons to neighboring water molecules. These findings are quite interesting, since water is environmentally friendly, safe and biocompatible as compared with corrosive acid/base and organic electrolytes. Therefore, the proof-of-concept pure water electrolyte could open new avenues for applications in bioelectronics.

Unusual adsorption phenomena, such as breathing and negative gas adsorption (NGA), are rare and challenge our thermodynamic understanding of adsorption in deformable porous solids. In particular, NGA appears to break the rules of thermodynamics in these materials by exhibiting a spontaneous release of gas accompanying an increase in pressure. This anomaly relies on long-lived metastable states. A fundamental understanding of this process is desperately required for the discovery of new materials with this exotic property. Interestingly, NGA was initially observed upon adsorption of methane at relatively low temperature, close to the respective standard boiling point of the adsorptive, and no NGA was observed at elevated temperatures. In this contribution, we present an extensive investigation of adsorption of an array of gases at various temperatures on DUT-49, a material which features an NGA transition. Experiments, featuring a wide range of gases and vapors at temperatures ranging from 21-308 K, were used to identify for each guest a critical temperature range in which NGA can be detected. The experimental results were complemented by molecular simulations that help to rationalize the absence of NGA at elevated temperatures, and the non-monotonic behavior present upon temperature decrease. Furthermore, this in-depth analysis highlights the crucial thermodynamic and kinetic conditions for NGA, which are unique to each guest and potentially other solids with similar effects. We expect this exploration to provide detailed guidelines for experimentally discovering NGA and related "rule breaking"phenomena in novel and already known materials, and provide the conditions required for the application of this effect, for example as pressure amplifying materials.