Search

Abstract: A series of novel coordination polymers [Ln2(NIPH)2(Suc)(H2O)2] [Ln=Tb(1), Eu(2), Gd(3), Dy(4), Ho(5), Er(6), Tm(7) and Y(8); H2NIPH=5-nitroisophthalic acid; H2Suc=succinic acid] have been synthesized by the reaction of nitrate salts of Ln (III) with 5-nitroisophthalic acid and succinic acid under hydrothermal conditions and were characterized by elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction. Structural analyses reveal that all eight complexes have 3-D structures, and in these complexes, they were crystallized in monoclinic space group C2/c. Two crystallographically equivalent Ln atoms are bridged by two especial carboxylate groups in chelating/bridging bidentate fashion to give a dinuclear lanthanide building block [Ln2O2(CO2R)8] with shorter separations of Ln···Ln. Those blocks are interconnected to each other leading to a 1-D infinitely extending chain, and then these chains are linked to each other through the NIPH to a 2-D open framework, which further link to each other to form 3-D networks. The thermogravimetric analysis of 1–8 and photoluminescent properties of 1 and 2 are discussed in detail. [Copyright &y& Elsevier]

A new 3-D inorganic–organic hybrid framework microporous material Zn3(bbdc)3(4,4′-bpy)·2(DMF)·4(H2O) (1), which is constructed by coordination of zinc ions with 4,4′-bibenzene-dicarboxylic acid (H2bbdc) and 4,4′-bipyridine (4,4′-bpy), was obtained at mild synthesis condition. Crystallographic data for the compound (1), C58H54N4O18Zn3, orthorhombic, space group Pbcn, a=14. 532(3) A˚, b=25.037(5) A˚, c=18.184(4) A˚, Z=4, V=6616(2) A˚3. [Copyright &y& Elsevier]

Organic polymers are considered promising candidates for next‐generation green electrode materials in lithium‐ion batteries (LIBs). However, achieving long cycling stability and capacity retention at high current densities remains a significant challenge due to weak structural stability and low conductivity. In this study, we report the synthesis of two novel polyimide covalent organic frameworks (PI‐COFs), COF‐JLU85 and COF‐JLU86, by combining truxenone‐based triamine and linear acid anhydride through polymerization. These PI‐COFs feature layers with pore channels embedded with 18 carbonyl groups, facilitating rapid lithium‐ion diffusion and enhancing structural stability under high current densities. Compared to previously reported organic polymer materials, COF‐JLU86 demonstrates the excellent performance at high current densities, with an impressive specific capacity of 1161.1 mA h g−1 at 0.1 A g−1, and outstanding cycling stability, retaining 1289.8 mA h g−1 at 2 A g−1 after 1500 cycles and 401.1 mA h g−1 at 15 A g−1 after 10000 cycles. Additionally, in situ infrared spectroscopy and density functional theory (DFT) calculations provide mechanistic insights, revealing that the high concentration of carbonyl redox‐active sites and the optimized electronic structure contribute to the excellent electrochemical performance. These results highlight the potential of PI‐COFs as high‐performance organic electrode materials for LIBs, offering a promising solution to the challenges of long‐term stability and capacity retention at high current densities. [ABSTRACT FROM AUTHOR]

Achieving enhanced or blue‐shifted emission from piezochromic materials remains a major challenge. Covalent organic frameworks (COFs) are promising candidates for the development of piezochromic materials owing to their dynamic structures and adjustable optical properties, where the emission behaviors are not solely determined by the functional groups, but are also greatly influenced by the specific geometric arrangement. Nevertheless, this area remains relatively understudied. In this study, a successful synthesis of a series of bicarbazole‐based COFs with varying topologies, dimensions, and linkages was conducted, followed by an investigation of their structural and emission properties under hydrostatic pressure generated by a diamond anvil cell. Consequently, these COFs exhibited distinct piezochromic behaviors, particularly a remarkable pressure‐induced emission enhancement (PIEE) phenomenon with a 16‐fold increase in fluorescence intensity from three‐dimensional COFs, surpassing the performance of CPMs and most organic small molecules with PIEE behavior. On the contrary, three two‐dimensional COFs with flexible structures exhibited rare blue‐shifted emission, whereas the variants with rigid and conjugated structures showed common red‐shifted and reduced emission. Mechanism research further revealed that these different piezochromic behaviors were primarily determined by interlayer distance and interaction. This study represents the first systematic exploration of the structures and emission properties of COFs through pressure‐treated engineering and provides a new perspective on the design of piezochromic materials. [ABSTRACT FROM AUTHOR]

The electrochemical production of hydrogen peroxide (H2O2) using metal‐free catalysts has emerged as a viable and sustainable alternative to the conventional anthraquinone process. However, the precise architectural design of these electrocatalysts poses a significant challenge, requiring intricate structural engineering to optimize electron transfer during the oxygen reduction reaction (ORR). Herein, we introduce a novel design of covalent organic frameworks (COFs) that effectively shift the ORR from a four‐electron to a more advantageous two‐electron pathway. Notably, the JUC‐660 COF, with strategically charge‐modified benzyl moieties, achieved a continuous high H2O2 yield of over 1200 mmol g−1 h−1 for an impressive duration of over 85 hours in a flow cell setting, marking it as one of the most efficient metal‐free and non‐pyrolyzed H2O2 electrocatalysts reported to date. Theoretical computations alongside in situ infrared spectroscopy indicate that JUC‐660 markedly diminishes the adsorption of the OOH* intermediate, thereby steering the ORR towards the desired pathway. Furthermore, the versatility of JUC‐660 was demonstrated through its application in the electro‐Fenton reaction, where it efficiently and rapidly removed aqueous contaminants. This work delineates a pioneering approach to altering the ORR pathway, ultimately paving the way for the development of highly effective metal‐free H2O2 electrocatalysts. [ABSTRACT FROM AUTHOR]

A three-dimensional metal–covalent organic framework (3D-MCOF) based on cyclic trinuclear units was synthesized using organic tetrahedral linkers and copper-based cyclic trinuclear complexes. The novel type of 3D-MCOF, named 3D-CTU-MCOF, with the ctn topology, is reported herein for the first time. Our study demonstrated enhanced electrocatalytic capacity for CO2 reduction reaction of 3D-CTU-MCOF compared to independent cyclic trinuclear units. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel composite photocatalyst NiS/CdS@DUT-67 is prepared. • The separation and transport of photogenerated carriers are assisted by NiS and DUT-67. • NiS/CdS@DUT-67 achieves high hydrogen production rate as 9618 μmol·g NiS/CdS −1·h−1. Metal-organic framework materials (MOFs) and their derivatives have been widely used in the field of photocatalytic water decomposition for hydrogen production. In this study, NiS/CdS was initially acquired and subsequently combined with DUT-67 via ultrasound to create a unique ternary photocatalyst NiS/CdS@DUT-67. The rate of hydrogen production for NiS/CdS@DUT-67 is 9618 μmol·g NiS/CdS −1·h−1 for NiS/CdS@DUT-67, which is 32 times and 2.5 times higher than that for CdS and NiS/CdS, respectively. Of particular interest is the fact that even after 50 h of photocatalysis, the hydrogen production rate did not show a significant decrease, demonstrating its excellent stability compared to CdS and NiS/CdS. In this ternary system, NiS and DUT-67 function as dual co-catalysts for CdS, collaborating to enhance charge separation during the photocatalysis. This study presents a clear demonstration of the advantages of utilizing metal–organic framework derivatives (MOF-derivatives) cophotocatalysts and their synergistic effect, resulting in improved photocatalytic activity and stability of semiconductors. This innovative approach provides a new perspective on constructing photocatalytic materials with exceptional performance. [ABSTRACT FROM AUTHOR]

Exploiting advanced amphiphilic solid catalysts is crucial to the development of Pickering emulsion catalysis. Herein, covalent organic framework (COF) nanoparticles constructed with highly hydrophobic monomers as linkers were found to show superior amphiphilicity and they were then developed as a new class of solid emulsifiers for Pickering emulsion catalysis. Employing amphiphilic COFs as solid emulsifiers, Pickering emulsions with controllable emulsion type and droplet sizes were obtained. COF materials have also been demonstrated to serve as porous surface coatings to replace traditional surface modifications for stabilizing Pickering emulsions. After implanting Pd nanoparticles into amphiphilic COFs, the obtained catalyst displayed a 3.9 times higher catalytic efficiency than traditional amphiphilic solid catalysts with surface modifications in the biphasic oxidation reaction of alcohols. Such an enhanced activity was resulted from the high surface area and regular porous structure of COFs. More importantly, because of their tunable pore diameters, Pickering emulsion catalysis with remarkable size selectivity was achieved. This work is the first example that COFs were applied in Pickering emulsion catalysis, providing a platform for exploring new frontiers of Pickering emulsion catalysis. [ABSTRACT FROM AUTHOR]

Due to their large surface area and pore volume, three-dimensional covalent organic frameworks (3D COFs) have emerged as competitive porous materials. However, structural dynamic behavior, often observed in imine-linked 3D COFs, could potentially unlock their potential application in gas storage. Herein, we showed how a pre-locked linker strategy introduces breaking dynamic behavior in 3D COFs. A predesigned planar linker-based 3,8-diamino-6-phenylphenanthridine (DPP) was prepared to produce non-dynamic 3D JUC-595, as the benzylideneamine moiety in DPP locked the linker flexibility and restricted the molecular bond rotation of the imine linkages. Upon solvent inclusion and release, the PXRD profile of JUC-595 remained intake, while JUC-594 with a flexible benzidine linker experienced crystal transformation due to framework contraction–expansion. As a result, the activated JUC-595 achieved higher surface areas (754 m2 g−1) than that of JUC-594 (548 m2 g−1). Furthermore, improved CO2 and CH4 storages were also seen in JUC-595 compared with JUC-594. Impressively, JUC-595 recorded a high normalized H2 storage capacity that surpassed other reported high-surface area 3D COFs. This works shows important insights on manipulating the structural properties of 3D COF to tune gas storage performance. [ABSTRACT FROM AUTHOR]

The design and synthesis of covalent organic frameworks (COFs) with high chemical stability pose significant challenges for practical applications. Although a growing number of robust COFs have been developed and employed for a broad scope of applications, the assessment of COF stability has primarily relied on qualitative descriptions, lacking a rational and quantitative assessment. Herein, a novel assessment method is presented that enables visual and quantitative depiction of COF stability. By analyzing the PXRD patterns of chemically stable β‐ketoenamine‐based COFs (KEA‐COFs), two crystallinity‐dependent parameters are identified, the relative intensity (I2θrel) and the relative area (A2θrel) of the main peak (2θ), which are expected to establish a standardized criterion for assessing COF crystallinity. Based on these parameters, the crystalline changes after stability tests can be visually presented, which provides a rational and quantitative assessment of their stability. This study not only demonstrates the remarkable chemical stability of KEA‐COFs, but also provides valuable insights into the quantitative evaluation of COFs' crystallinity and stability. [ABSTRACT FROM AUTHOR]

Hydroxide (OH−)-exchange membranes (HEMs) are important polymer electrolytes enabling the use of affordable and earth-abundant electrocatalysts for electrochemical energy-conversion devices such as HEM fuel cells, HEM electrolyzers, and HEM solar hydrogen generators. Many HEM cations exist, featuring desirable properties, but new cations are still needed to increase chemical stability at elevated temperatures. Here we introduce the permethyl cobaltocenium [(C5Me5)2Co(III)+ or Cp*2Co+] as an ultra-stable organic cation for polymer HEMs. Compared with the parent cobaltocenium [(C5H5)2Co(III)+ or Cp2Co+], Cp*2Co+ has substantially higher stability and basicity. With polysulfone as an example, we demonstrated the feasibility of covalently linking Cp*2Co+ cation to polymer backbone and prepared Cp*2Co+-functionalized membranes as well. The new cation may be useful in designing more durable HEM electrochemical devices. [ABSTRACT FROM AUTHOR]

Piezochromic materials with pressure‐dependent photoluminescence tuning properties are important in many fields, such as mechanical sensors, security papers, and storage devices. Covalent organic frameworks (COFs), as an emerging class of crystalline porous materials (CPMs) with structural dynamics and tunable photophysical properties, are suitable for designing piezochromic materials, but there are few related studies. Herein, we report two dynamic three‐dimensional COFs based on aggregation‐induced emission (AIE) or aggregation‐caused quenching (ACQ) chromophores, termed JUC‐635 and JUC‐636 (JUC=Jilin University China), and for the first time, study their piezochromic behavior by diamond anvil cell technique. Due to the various luminescent groups, JUC‐635 has completely different solvatochromism and molecular aggregation behavior in the solvents. More importantly, JUC‐635 with AIE effect exhibits a sustained fluorescence upon pressure increase (≈3 GPa), and reversible sensitivity with high‐contrast emission differences (Δλem=187 nm) up to 12 GPa, superior to other CPMs reported so far. Therefore, this study will open a new gate to expand the potential applications of COFs as exceptional piezochromic materials in pressure sensing, barcoding, and signal switching. [ABSTRACT FROM AUTHOR]

Highlights: JUC-610-nanosheet exhibits highly efficient oxygen reduction reaction (ORR) catalytic activity in alkaline electrolyte with half-wave potential of 0.72 V versus reversible hydrogen electrode, which is one of the best covalent organic frameworks (COF)-based ORR electrocatalysts reported so far. It has been confirmed by experiments and density functional theory calculations that the abundant electrophilic structure in Q3CTP-COFs induces a highly density of carbon active sites, and the unique bilayer stacking facilitates the exposure of active carbon sites and accelerates the mass diffusion during ORR. JUC-610-nanosheet can also serve as a promising cathode for Zn-air batteries (power density of 156 mW cm–2 at 300 mA cm–2), which promotes the development of metal-free carbon-based electrocatalysts. Metal-free carbon-based materials are considered as promising oxygen reduction reaction (ORR) electrocatalysts for clean energy conversion, and their highly dense and exposed carbon active sites are crucial for efficient ORR. In this work, two unique quasi-three-dimensional cyclotriphosphazene-based covalent organic frameworks (Q3CTP-COFs) and their nanosheets were successfully synthesized and applied as ORR electrocatalysts. The abundant electrophilic structure in Q3CTP-COFs induces a high density of carbon active sites, and the unique bilayer stacking of [6 + 3] imine-linked backbone facilitates the exposure of active carbon sites and accelerates mass diffusion during ORR. In particular, bulk Q3CTP-COFs can be easily exfoliated into thin COF nanosheets (NSs) due to the weak interlayer π–π interactions. Q3CTP-COF NSs exhibit highly efficient ORR catalytic activity (half-wave potential of 0.72 V vs. RHE in alkaline electrolyte), which is one of the best COF-based ORR electrocatalysts reported so far. Furthermore, Q3CTP-COF NSs can serve as a promising cathode for Zn-air batteries (delivered power density of 156 mW cm–2 at 300 mA cm–2). This judicious design and accurate synthesis of such COFs with highly dense and exposed active sites and their nanosheets will promote the development of metal-free carbon-based electrocatalysts. [ABSTRACT FROM AUTHOR]

The uniquely tunable nature of covalent organic frameworks (COFs), whose pore size and stability can be controlled by choosing diverse organic building blocks and linkage types, makes COFs potential candidates for the membrane separation. Therefore, the preparation of membranes with effective separation efficiency based on COFs has aroused great interest among researchers. Although solvothermal approach has been the most popular method for the preparation of COF membranes, fabricating COF membranes at room temperature (RT) will provide a simple and captivating strategy for separation membranes. Herein, a P‐COF membrane on porous alumina substrate at RT, showing 99.7% rejection of rhodamine B and excellent water permeance up to 52 L m−2 h−1 bar−1, which can effectively purify wastewater is successfully obtained. P‐COF is directly grown on alumina to form the composite membrane, which enhances the mechanical strength of COF membrane and avoids the risk of damaging the membrane structure during the transfer process of self‐standing membrane. Moreover, P‐COF membrane is grown at RT, which is more energy efficient than the conventional solvothermal method. Thus, it is of great significance to obtain COF membranes with excellent nanofiltration performance in a simple and mild condition to alleviate environmental and energy concerns. [ABSTRACT FROM AUTHOR]

The Co@N-C nanocatalysts derived by direct carbonization of Co-containing metal organic framework (MOF) structure under N 2 flow have been prepared for their application as catalyst in reducing 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) assisted by NaBH 4 . Under inert gas treatment, we obtained Co 0 phase-based nanocatalyst which inherited their former MOF precursor morphology. The resultant nanocatalysts were denoted as Co@N-C 600, 700, 800 corresponding to the respective carbonization temperatures and each was characterized using powder X-Ray diffraction (PXRD), thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), surface area-porosity and transmission electron microscopy (TEM). We found that Co@N-C 700 presented the desired properties with largest surface area (262.800 m 2 /g), high crystallinity with better Co nanoparticle dispersed on the C-N matrix and sufficient amount of Co per gram of nanocatalyst without obvious particle aggregation. All of the nanocatalysts could catalyze 1.25 mM 4-NP to 4-AP per mg catalyst per second which is comparatively remarkable performance compared to previous reposts. Most importantly, as predicted Co@N-C 700 possessed the highest catalytic activity with 6 times consecutive catalytic reactions in successfully reducing 100% 4-NP to 4-AP. The catalytic activity was speculated due to the Co nanoparticle as catalytic active site worked synergistically with C-N matrix as conductive layer which could provide and transport electrons for catalytic reduction reaction. [ABSTRACT FROM AUTHOR]

The emergence of metal‐organic frameworks (MOFs) provides a new platform of low‐cost and color‐saturated blue light‐emitting diodes ideal for display and solid‐state lighting applications. However, numerous established MOFs still exhibit weak deep‐blue‐light emission (<450 nm) owing to low energy/charge transfer efficiency. Here a pressure‐treated strategy to greatly enhance photoluminescence performance of deep‐blue light‐emitting Y(BTC)(H2O)6 (H3BTC: benzene‐1,3,5‐tricarboxylic acid) is reported. Pressure‐treated Y(BTC)(H2O)6 exhibits a bright emission at 409 nm with a photoluminescence quantum yield from the initial 2.8% increasing to 75.0%. The hydrogen bonding cooperativity effect increases hydrogen bond binding energy after pressure treatment and thus the planarization structure is locked. The increased electronic transition diversity and oscillator strength originating from the planarization structure are highly responsible for boosting metal‐to‐ligand charge transfer. The findings in this study provide significant insights into the underlying mechanism of the structure‐property relationship in Y(BTC)(H2O)6 and offer a promising strategy to harvest deep‐blue‐emitting MOFs materials. [ABSTRACT FROM AUTHOR]

Covalent organic frameworks (COFs) are proposed as promising candidates for engineering advanced molecular sieving membranes due to their precise pore sizes, modifiable pore environment, and superior stability. However, COFs are insoluble in common solvents and do not melt at high temperatures, which presents a great challenge for the fabrication of COF‐based membranes (COFMs). Herein, for the first time, a new synthetic strategy is reported to prepare continuous and intact self‐standing COFMs, including 2D N‐COF membrane and 3D COF‐300 membrane. Both COFMs show excellent selectivity of H2/CO2 mixed gas (13.8 for N‐COF membrane and 11 for COF‐300 membrane), and especially ultrahigh H2 permeance (4319 GPU for N‐COF membrane and 5160 GPU for COF‐300 membrane), which is superior to those of COFMs reported so far. It should be noted that the overall separation performance of self‐standing COFMs exceeds the Robeson upper bound. Furthermore, a theoretical study based on Grand Canonical Monte Carlo (GCMC) simulation is performed to explain the excellent separation of H2/CO2 through COFMs. Thus, this facile preparation method will provide a broad prospect for the development of self‐standing COFMs with highly efficient H2 purification. [ABSTRACT FROM AUTHOR]

Three‐dimensional covalent organic frameworks (3D COFs) with spatially periodic networks demonstrate significant advantages over their 2D counterparts, including enhanced specific surface areas, interconnected channels, and more sufficiently exposed active sites. Nevertheless, research on these materials has met an impasse due to serious problems in crystallization and stability, which must be solved for practical applications. In this Minireview, we first summarize some strategies for preparing functional 3D COFs, including crystallization techniques and functionalization methods. Hereafter, applications of these functional materials are presented, covering adsorption, separation, catalysis, fluorescence, sensing, and batteries. Finally, the future challenges and perspectives for the development of 3D COFs are discussed. [ABSTRACT FROM AUTHOR]

Lanthanide metal–organic frameworks are of great interest in the development of photoluminescence (PL) materials owing to their structural tunability and intrinsic features of lanthanide elements. However, there exists some limitations arising from poor matching with metal ions, thereby exhibiting a weak ligand‐to‐metal energy transfer (LMET) process. Here we demonstrate a pressure‐treated strategy for achieving high PL performance in green‐emitting Tb(BTC)(H2O)6. The PL quantum yield of pressure‐treated sample increased from 50.6 % to 90.4 %. We found that the enhanced hydrogen bonds locked the conjugated configuration formed by two planes of carboxyl group and benzene ring, enabling the promoted intersystem crossing to effectively drive LMET. Moreover, the optimized singlet and triplet states also validated the facilitated LMET process. This work opens the opportunity of structure optimization to improve PL performance in MOFs by pressure‐treated engineering. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Three‐dimensional (3D) covalent organic frameworks (COFs) are crystalline porous polymers with potential in numerous high‐tech applications, but the linkages involved in their synthesis are still rather limited. Herein, we report novel 3D sp2 carbon‐linked COFs fabricated by the formation reaction of C=C bonds and their application in fluorescence imaging. These new COFs, namely JUC‐580 and JUC‐581, show high stability and excellent light‐emitting properties in solid state and dispersed in various solvents. Furthermore, we investigate the potential application of JUC‐581 as a drug carrier combined with fluorescence imaging. These results indicate that 3D sp2 carbon‐linked COFs are not only potential drug‐loaded and sustained release materials but also promising cell fluorescent stains. This study thus expands the structural categories of 3D COFs based on different linkages, and promotes their prospective applications for biomedicine and fluorescent materials. [ABSTRACT FROM AUTHOR]

The development of novel zeolite‐like materials with large channel windows and high stability is of importance but remains a tremendous challenge. Herein, we report the first example of a 3D covalent organic framework with zeolitic network, namely the zeolitic organic framework (ZOF). By combining two kinds of tetrahedral building blocks with fixed or relatively free bond angles, ZOF‐1 with the zeolitic crb net has been successfully synthesized. Its structure was determined by the single‐crystal 3D electron diffraction technique. Remarkably, ZOF‐1 shows high chemical stability, large pore size (up to 16 Å), and excellent specific surface area (≈2785 m2 g−1), which is superior to its analogues with the same network, including traditional aluminosilicate zeolites and zeolitic imidazole frameworks. This study thus opens a new avenue to construct zeolite‐like materials with pure organic frameworks and will promote their potential applications in adsorption and catalysis for macromolecules. [ABSTRACT FROM AUTHOR]

Cell-mimicking nanoreactors with fascinating physicochemical properties have attracted impressive interest in sustainable catalysis, energy conversion, environmental remediation, and synthetic biology applications. Hollow covalent organic frameworks (COFs) are ideal candidates for rational construction of artificial nanoreactors owing to their high-order crystalline structure, well-defined cavity with permeable shells, tailorable chemical structures, and easy functionalization. The current review paper aims to present a comprehensive summary of the precise synthetic chemistry of hollow COF nanoreactors as well as their latest advancements in energy conversion and environmental molecule processing. Initially, we expound the definition of nanoreactor and highlight the fundamental properties of hollow COF nanoreactors. Subsequently, a detailed summary and discussion are presented in terms of the molecular-level synthesis strategies of these nanoreactors, providing a detailed analysis of the formation mechanisms reported to date. Following this, we present the significant achievements towards photo/electrocatalysis applications based on the unique features and structure-activity relationship of hollow COF nanoreactors. Lastly, we look ahead the development challenges and provide the perspective for the potential directions in future research. [Display omitted] • The definition and basic features of cell-mimicking hollow COF nanoreactor. • Precise synthetic chemistry for rational design of hollow COF nanoreactor. • Formation mechanisms for hollow COF nanoreactor. • Emerging applications in energy and environmental molecules conversion. • The challenges and outlooks for future research. [ABSTRACT FROM AUTHOR]

The development of bioinspired nano/subnano‐sized (<2 nm) ion channels is still considered a great challenge due to the difficulty in precisely controlling pore's internal structure and chemistry. Herein, for the first time, we report that three‐dimensional functionalized covalent organic frameworks (COFs) can act as an effective nanofluidic platform for intelligent modulation of the ion transport. By strategic attachment of 12‐crown‐4 groups to the monomers as ion‐driver door locks, we demonstrate that gating effects of functionalized COFs can be activated by lithium ions. The obtained materials exhibit an outstanding selective ion transmission performance with a high gating ratio (up to 23.6 for JUC‐590), which is among the highest values in metal ion‐activated solid‐state nanochannels reported so far. Furthermore, JUC‐590 offers high tunability, selectivity, and recyclability of ion transport proved by the experimental and simulated studies. [ABSTRACT FROM AUTHOR]

Owing to the finite building blocks and difficulty in structural identification, it remains a tremendous challenge to elaborately design and synthesize three‐dimensional covalent organic frameworks (3D COFs) with predetermined topologies. Herein, we report the first two cases of 3D COFs with the non‐interpenetrated hea net, termed JUC‐596 and JUC‐597, by using the combination of tetrahedral and triangular prism building units. Due to the presence of triptycene functional groups and fluorine atoms, JUC‐596 exhibits an exceptional performance in the H2 adsorption up to 305 cm3 g−1 (or 2.72 wt%) at 77 K and 1 bar, which is higher than previous benchmarks from porous organic materials reported so far. Furthermore, the strong interaction between H2 and COF materials is verified through the DFT theoretical calculations. This work represents a captivating example of rational design of functional COFs based on a reticular chemistry guide and demonstrates its promising application in clean energy storage. [ABSTRACT FROM AUTHOR]

[Display omitted] Covalent triazine-based frameworks (CTFs) have been emerged as a promising organic material for photocatalytic water splitting. However, all of the CTFs only are in the form of AA stacking model to participate in water splitting. Herein, two CTF-1 isomers with different stacking models (eclipsed AA, staggered AB) were obtained by modulating the reaction temperature. Interestingly, experimental and theoretical calculations showed that the crystalline AB stacking CTF-1 possessed a much higher activity for photochemical hydrogen evolution (362 μmol g−1 h−1) than AA stacking CTF-1 (70 µmol h−1 g−1) for the first time. The outstanding photochemical performance could be attributed to its distinct structural feature that allows more N atoms with higher electron-withdrawing property to be involved in the water reduction reaction. Notably, as a cathode material for PEC water reduction, AB stacking CTF-1 also demonstrated an excellent saturated photocurrent density up to 77 µA cm−2 at 0 V vs. RHE, which was superior to the AA stacking CTF-1 (47 µA cm−2). Furthermore, the correlation between stacking models and photocatalytic H 2 evolution of CTF-1 were investigated. This study thus paves the path for designing optimal photocatalyst and extending the novel applications of CTF-based materials. [ABSTRACT FROM AUTHOR]

With excellent designability, large accessible inner surface, and high chemical stability, covalent organic frameworks (COFs) are promising candidates as metal‐free heterogeneous catalysts. Here, we report two 3D radical‐based COFs (JUC‐565 and JUC‐566) in which radical moieties (TEMPO) are uniformly decorated on the channel walls via a bottom‐up approach. Based on grafted functional groups and suitable regular channels, these materials open up the application of COFs as highly efficient and selective metal‐free redox catalysts in aerobic oxidation of alcohols to relevant aldehydes or ketones with outstanding turn over frequency (TOF) up to 132 h−1, which has exceeded other TEMPO‐modified catalytic materials tested under similar conditions. These stable COF‐based catalysts could be easily recovered and reused for multiple runs. This study promotes potential applications of 3D functional COFs anchored with stable radicals in organic synthesis and material science. [ABSTRACT FROM AUTHOR]

• Two three-dimensional TTF-based COFs designed for photocatalytic nitrogen fixation. • 3D-TTF-COFs exhibit remarkable NH 3 generation rates of 313.8 and 106.8 μmol g−1h−1. • This work provides a strategy for constructing 3D COFs to achieve efficient PNRR. Preparing photocatalytic nitrogen-fixing catalysts that can effectively produce ammonia under mild conditions is an urgent problem to be solved. Herein, we for the first time present two three-dimensional tetrathiafulvalene-based covalent organic frameworks with high crystallinity and permanent pores, termed 3D-TTF-COFs, specifically designed for photocatalytic nitrogen fixation. The incorporation of TTF-based building blocks not only enhances light absorption capabilities but also facilitates the rapid transfer of photoexcited electrons, ensuring efficient charge carrier separation. It is worth noting that the resultant COFs exhibit remarkable NH 3 generation rates of 313.8 ± 5.6 and 106.8 ± 4.2 μmol g−1h−1 under visible light irradiation, surpassing the performance of most photocatalyst materials reported so far. Furthermore, these COFs maintain structural integrity and excellent performance during cyclic testing. Additionally, we carried out density functional theory calculations to elucidate the reaction mechanism between N 2 and NH 3. This work provides a feasible strategy for constructing 3D COFs to achieve efficient photocatalytic nitrogen fixation. [ABSTRACT FROM AUTHOR]

Abstract Highly crystalline and pure SSZ-13 zeolite is obtained by interzeolite conversion of zeolite Beta and zeolite L. Zeolite Beta is used without preliminary treatment, while zeolite L is subjected to dealumination in order to reach the Si/Al ratio appropriate for the synthesis of SSZ-13. The formation of SSZ-13 from conventional chemicals is also studied. The crystallization from zeolite precursors is much faster and provides pure and highly crystalline SSZ-13. The improved crystal growth kinetics is attributed to the directing effect of the dissolved Si-O-Al fragments from zeolite Beta and zeolite L frameworks. CHA-type zeolites obtained from dealuminated zeolite L crystallized faster, showed higher crystallinity and more defined crystals morphology in respect to those obtained from zeolite Beta. The dealuminated zeolite L was found to be an outstanding starting material for the crystallization of SSZ-13. Graphical abstract Image 1 Highlights • Zeolite Beta and Zeolite L are used as silica-alumina sources for the synthesis of zeolite SSZ-13 (CHA-type). • Factors controlling the interzeolite conversion of zeolite Beta and zeolite L in SSZ-13 are studied. • SSZ-13 shows higher crystallinity and crystallizes faster from zeolite precursors rather than the conventional gels. • Dealuminated zeolite L is a more efficient initial source for the SSZ-13 synthesis in respect to zeolite Beta. [ABSTRACT FROM AUTHOR]

The fluoride medium synthesis of zeolites, especially in the strongly acidic regions, yields products with unique characteristics such as ultra-hydrophobic surfaces and defect-free lattices. However, it is often difficult to incorporate aluminum into the framework of zeolites in this medium, limiting the acquisition and development of catalytic materials. The present paper shows that inter-zeolite transformation is efficient for obtaining ZSM-5 zeolites with lower Si/Al ratios in a strongly acidic fluoride medium. The critical point is that the parent zeolites can retain some locally ordered fragments during their dissolution, including framework Al atoms, and incorporate them into the ZSM-5 product. The acidic properties of the trans -crystallization products obtained in an acidic medium display significant differences from the traditional ZSM-5 with a similar Si/Al ratio in the amounts, strength, and types of the acid sites; thus, they behave differently in typical acid-catalysed reactions, such as dehydration of alcohols. In strongly acidic fluoride medium * BEA , FER and MOR -type zeolites transform readily into nanometer plates of MFI zeolite because they possess common mor CBU, while FAU zeolite transforms slowly to micrometer MFI crystals. These Al-rich ZSM-5 zeolites have unique acidity and perform differently in catalytic dehydration of light alcohols from the conventional ZSM-5. [Display omitted] • Al-rich ZSM-5 of Si/Al ∼ 20 obtained in acidic fluoride medium via inter-zeolite transformation. • In acidic medium * BEA , FER and MOR zeolites transforms readily into nanometersized plates of MFI because of common mor CBU. • FAU zeolite transforms slowly to micrometer MFI crystals. • These Al-rich ZSM-5 zeolites have unique acidity and perform differently in catalytic dehydration of light alcohols. [ABSTRACT FROM AUTHOR]

GLO:44U/25nov22:anie202215826-toc-0001.jpg PHOTO (COLOR): . gl GLO:44U/25nov22:anie202215826-toc-0001.jpg PHOTO (COLOR): . gl B A pressure-treatment strategy b for achieving high photoluminescence performance in a green-emitting Tb-based metal-organic framework is reported by Xinyi Yang, Qianrong Fang, Banglin Chen, Bo Zou et al. in their Research Article (e202210836). Fluorescent Monochromaticity, Green Photoluminescence Enhancement, Lanthanide Metal-Organic Frameworks, Ligand-to-Metal Energy Transfer, Pressure-Treated Engineering Cover Picture: Maximized Green Photoluminescence in Tb-Based Metal-Organic Framework via Pressure-Treated Engineering (Angew. [Extracted from the article]

Keywords: Fluorescent Monochromaticity; Green Photoluminescence Enhancement; Lanthanide Metal-Organic Frameworks; Ligand-to-Metal Energy Transfer; Pressure-Treated Engineering EN Fluorescent Monochromaticity Green Photoluminescence Enhancement Lanthanide Metal-Organic Frameworks Ligand-to-Metal Energy Transfer Pressure-Treated Engineering 1 1 1 11/22/22 20221125 NES 221125 B Die Photolumineszenzausbeute b in einem grün-emittierenden metallorganischen Gerüst auf Tb-Basis lässt sich mittels Druckbehandlung steigern, wie Xinyi Yang, Qianrong Fang, Banglin Chen, Bo Zou und Mitarbeiter in ihrem Forschungsartikel berichten (e202210836). Die verstärkten Wasserstoffbrücken verriegeln die konjugierte Konfiguration und ermöglichen Intersystem-Crossing, was den Metall-zu-Ligand-Energietransfer beschleunigt. Fluorescent Monochromaticity, Green Photoluminescence Enhancement, Lanthanide Metal-Organic Frameworks, Ligand-to-Metal Energy Transfer, Pressure-Treated Engineering. [Extracted from the article]

Abstract: Two new open-framework zinc phosphites, [M(C6N4H18)][Zn3(HPO3)4] (M=Ni, Co), have been prepared under hydrothermal conditions. Single-crystal X-ray diffraction analysis shows that [Ni(C6N4H18)][Zn3(HPO3)4] (1) and [Co(C6N4H18)][Zn3(HPO3)4] (2) are isostructural and both crystallize in the monoclinic space group C2/c with , , , °, , (), and (all data) for 1, and , , , , , (), and (all data) for 2. The structures of 1 and 2 are built up from strictly alternating ZnO4 tetrahedra and HPO3 pseudo-pyramids linked through oxygen vertices to form the three-dimensional (3-D) open-frameworks with multi-directional intersecting 12-membered ring (12-MR) channels. The M(TETA) (M=Ni, Co) complexes self-assembled under hydrothermal system connect with the inorganic host via M–O–P linkages and interact with inorganic framework through weak H-bonds. The two compounds show intense photoluminescence upon photoexcitation at 235nm. [Copyright &y& Elsevier]

Abstract: A new layered inorganic–organic hybrid aluminum phosphate-oxalate [H3N(CH2)4NH3]2[Al4(C2O4)(H2PO4)2(PO4)4]·4[H2O](AlPO-CJ25) has been synthesized hydrothermally, by using 1,4-diaminobutane (DAB) as structure-directing agent. The structure has been solved by single-crystal X-ray diffraction analysis and further characterized by IR, 31P MAS NMR, TG-DTA as well as compositional analyses. Crystal data: the triclinic space group P-1, a=8.0484(7)Å, b=8.8608(8)Å, c=13.2224(11)Å, α=80.830(6)°, β=74.965(5)°, γ=78.782(6)°, Z=2, R 1[ I >2 σ ( I )]=0.0511 and wR 2(all data)=0.1423. The alternation of AlO4 tetrahedra and PO4 tetrahedra gives rise to the four-membered corner-sharing chains, which are interconnected through AlO6 octahedra to form the layered structure with 4,6-net sheet. Interestingly, oxalate ions are bis-bidentately bonded by participating in the coordination of AlO6, and bridging the adjacent AlO6 octahedra. The layers are held with each other through strong H-bondings between the terminal oxygens. The organic ammonium cations and water molecules are located in the large cavities between the interlayer regions. [Copyright &y& Elsevier]