Integrating Levels of Hierarchical Organization in Porous Organic Molecular Materials

Porous organic molecular materials(POMMs)are an emergent class of molecular-based materials characterized by the formation of extended porous frameworks,mainly held by non-covalent interactions.POMMs represent a variety of chemical families,such as hydrogen-bonded organic frameworks,porous organic salts,porous organic cages,C-H···πmicroporous crystals,supramolecular organic frameworks,π-organic frameworks,halogen-bonded organic framework,and intrinsically porous molecular materials.In some porous materials such as zeolites and metal organic frameworks,the integration of multiscale has been adopted to build materials with multifunctionality and optimized properties.Therefore,considering the significant role of hierarchy in porous materials and the growing importance of POMMs in the realm of synthetic porous materials,we consider it appropriate to dedicate for the first time a critical review covering both topics.Herein,we will provide a summary of literature examples showcasing hierarchical POMMs,with a focus on their main synthetic approaches,applications,and the advantages brought forth by introducing hierarchy.

Recent Advances in Multifunctional Reticular Framework Nanoparticles:A Paradigm Shift in Materials Science Road to a Structured Future

Porous organic frameworks(POFs)have become a highly sought-after research domain that offers a promising avenue for developing cutting-edge nanostructured materials,both in their pristine state and when subjected to various chemical and structural modifications.Metal–organic frameworks,covalent organic frameworks,and hydrogen-bonded organic frameworks are examples of these emerging materials that have gained significant attention due to their unique properties,such as high crystallinity,intrinsic porosity,unique structural regularity,diverse functionality,design flexibility,and outstanding stability.This review provides an overview of the state-of-the-art research on base-stable POFs,emphasizing the distinct pros and cons of reticular framework nanoparticles compared to other types of nanocluster materials.Thereafter,the review highlights the unique opportunity to produce multifunctional tailoring nanoparticles to meet specific application requirements.It is recommended that this potential for creating customized nanoparticles should be the driving force behind future synthesis efforts to tap the full potential of this multifaceted material category.

Recent Progress in Synthesis, Mechanism and Applications of Zinc-Based Metal-Organic Frameworks for Fluorescent Sensing

As more and more pollutants threaten human health, it is necessary and essential to develop sensitive, accurate and rapid methods and sensory materials to detect harmful substance. Metal-organic frameworks (MOFs) are inorganic-organic hybrids assembled from inorganic metal ions or clusters and suitable organic ligands. Zinc-based MOFs (Zn-MOFs) have emerged as one of the most promising sensory material of MOFs for practical applications, and attracted significant attention due to structural diversity and incomparable stability properties. However, there are few reviews on systemic summary of synthesis design, mechanism and application of Zn-MOFs. In this review, we summarize the synthesis design methods, structure types and luminescence mechanism of Zn-MOFs sensor recognition in the past ten years and their applications in metal cations, anions, organic compounds and other analytes. Finally, we present a short conclusion, and look forward to the future development direction of Zn-MOFs.

An imine-linked covalent organic framework as the host material for sulfur loading in lithium–sulfur batteries

Lithium–sulfur(Li–S) batteries have high theoretical specific capacity, providing new opportunities for the next generation of secondary battery. Covalent organic framework(COF) as a new porous crystalline material has been used as the host material in Li–S battery to improve the cell's cycling stability. In this paper, an imine-linked TAPB-PDA-COF was applied as the host material for sulfur loading(60%) in Li–S battery. The TAPB-PDA-COF has a beehive-like morphology with high thermal stability(up to 500 ℃).In the electrochemical experiment, the performance of the composite cathode with acetylene black(AB) and super-P(S-P) as the conductive additives was studied individually. The initial discharge capacity under 0.2 A/g current density was 991 mAh/g and 1357 mAh/g for TAPB-PDA-COF/S@A-B and TAPB-PDACOF/S@S-P, respectively. The better result of S-P based cathode than A-B could be due to the better conductivity of the S-P, as proved by the EIS results. When further increased the current density to 2 A/g,the S-P based composite cathode can still deliver a comparable initial discharge capacity of 630 and 274 mAh/g capacity remained after 940 cycles. This results will inspire researchers develop more suitable conductive additives together with the host materials for high performance Li–S battery.

Synthesis of covalent organic framework materials and their application in the field of sensing

Covalent organic frameworks(COFs)are an emerging type of porous crystalline polymers formed by combining strong covalent bonds with organic building blocks.Due to their large surface area,high intrinsic pore space,good crystallization properties,high stability,and designability of the resultant units,COFs are widely studied and used in the fields of gas adsorption,drug transport,energy storage,photoelectric catalysis,electrochemistry,and sensors.In recent years,the rapid development of the Internet of Things and people’s yearning for a better life have put forward higher and more requirements for sensors,which are the core components of the Internet of Things.Therefore,this paper reviews the recent progress of COFs in synthesis methods and sensing applications,especially in the last five years.This paper first introduces structure,properties,and synthesis methods of COFs and discusses advantages and disadvantages of different synthesis methods.Then,the research progress of COFs in different sensing fields,such as metal ion sensors,gas sensors,biomedical sensors,humidity sensors,and pH sensors,is introduced systematically.Conclusions and prospects are also presented in order to provide a reference for researchers concerned with COFs and sensors.

A General Synthesis Method for Covalent Organic Framework and Inorganic 2D Materials Hybrids

Two-dimensional(2D)inorganic/organic hybrids provide a versatile platform for diverse applications,including electronic,catalysis,and energy storage devices.The recent surge in 2D covalent organic frameworks(COFs)has introduced an organic counterpart for the development of advanced 2D organic/inorganic hybrids with improved electronic coupling,charge separation,and carrier mobility.However,existing synthesis methods have primarily focused on few-layered film structures,which limits scalability for practical applications.Herein,we present a general synthesis approach for a range of COF/inorganic 2D material hybrids,utilizing 2D inorganic materials as both catalysts and inorganic building blocks.By leveraging the intrinsic Lewis acid sites on the inorganic 2D materials such as hexagonal boron nitride(hBN)and transition metal dichalcogenides,COFs with diverse functional groups and topologies can grow on the surface of inorganic 2D materials.The controlled 2D morphology and excellent solution dispersibility of the resulting hybrids allow for easy processing into films through vacuum filtration.As proof of concept,hBN/COF films were employed as filters for Rhodamine 6G removal under flow-through conditions,achieving a removal rate exceeding 93%.The present work provides a simple and versatile synthesis method for the scalable fabrication of COF/inorganic 2D hybrids,offering exciting opportunities for practical applications such as water treatment and energy storage.

Covalent organic frameworks as heterogeneous catalysts

Covalent organic frameworks （COFs）, established as an emerging class of crystalline porous polymers with high surface area, structural diversity, and esignability, attract much interest and exhibit potential applications in catalysis. In this review, we summarize the use of COFs as a versatile platform to develop heterogeneous catalysts for a variety of chemical reactions. Catalytic COFs are categorized in accordance with the types of active sites, involving single functional active sites, bifunctional active sites, and metal nanoparticles （NPs） embedded in pores. Special emphasis is placed on the deliberate or incidental synthesis strategies, the stability, the heterogeneity, and the shape/size selectivity for COF catalysis. Moreover, a description of the application of COFs as photocatalysts and electrocatalysts is presented. Finally, the prospects of COFs in catalysis and remaining issues in this field are indicated.

Reducing dielectric confinement effect in ionic covalent organic nanosheets to promote the visible-light-driven hydrogen evolution

Ultra-thin two-dimensional(2D)organic semiconductors are promising candidates for photocatalysts because of the short charge diffusion pathway and favorable exposure of active sites plus the versatile architecture.Nonetheless,the inherent dielectric confinement of 2D materials will induce a strong exciton effect hampering the charge separation.Herein,we demonstrated an effective way to reduce the dielectric confinement effect of 2D ionic covalent organic nanosheets(iCONs)by tailoring the functional group via molecular engineering.Three ultra-thin CONs with different functional groups and the same ionic moieties were synthesized through Schiff base condensation between ionic amino monomer triaminoguanidinium chloride(TG)and aldehyde linkers.The integration of the hydroxyl group was found to significantly increase the dielectric constant by enhancing the polarizability of ionic moieties,and thus reduced the dielectric confinement and the corresponding exciton binding energy(E_(b)).The champion hydroxyl-functional iCON exhibited promoted exciton dissociation and in turn a high photocatalytic hydrogen production rate under visible-light irradiation.This work provided insights into the rationalization of the dielectric confinement effect of low-dimensional photocatalysts.

Metal-organic frameworks for highly efficient oxygen electrocatalysis

Metal‐organic frameworks(MOFs)are a series of highly porous crystalline materials,which are built from inorganic metal nodes and organic linkers through coordination bonds.Their unique porous structural features(such as high porosity,high surface areas,and highly ordered nanoporous structures)and designable structures and compositions have facilitated their use in gas capture,separation,catalysis,and energy storage and conversion.Recently,the design and synthesis of pure MOFs and their derivatives have opened new routes to develop highly efficient electrocatalysts toward oxygen reduction reactions(ORR)and oxygen evolution reactions(OER),which are the core electrode reactions in many energy storage and conversion techniques,such as metal‐air batteries and fuel cells.This review first discusses recent progress in the synthesis and the electrocatalytic applications of pure MOF‐based electrocatalysts toward ORR or OER,including pure MOFs,MOFs decorated with active species,and MOFs incorporated with conductive materials.The following section focuses on the advancements of the design and preparation of various MOF‐derived materials-such as inorganic nano‐(or micro‐)structures/porous carbon composites,pure porous carbons,pure inorganic nano‐(or micro‐)structured materials,and single‐atom electrocatalysts-and their applications in oxygen electrocatalysis.Finally,we present a conclusion and an outlook for some general design strategies and future research directions of MOF‐based oxygen electrocatalysts.

Fabrication of edge-curled petals-like covalent organic frameworks and their properties for extracting indole alkaloids from complex biological samples

In this study,a functionalized covalent-organic framework(COF)was first synthesized using porphyrin as the fabrication unit and showed an edge-curled,petal-like and well-ordered structure.The synthesized COF was then introduced to prepare porous organic polymer monolithic materials(POPMs).Two composite POPM/COF monolithic materials with rod shapes,referred to as sorbent A and sorbent B,were prepared in stainless steel tubes using different monomers.Sorbents A and B exhibited relatively uniform porous structures and enhanced specific surface areas of 153.14 m;/g and 80.01 m;/g,respectively.The prepared composite monoliths were used as in-tube solid-phase extraction(SPE)sorbents combined with HPLC for the on-line extraction and quantitative analytical systems.Indole alkaloids(from Catharanthus roseus G.Don and Uncaria rhynchophylla(Miq.)Miq.Ex Havil.)contained in mouse plasma were extracted and quantitatively analyzed using the online system.The two composite multifunctional monoliths showed excellent clean-up ability for complex biological matrices,as well as superior selectivity for target indole alkaloids.Method validation showed that the RSD values of the repeatability(n=6)were≤3.46%,and the accuracy expressed by the spiked recoveries was in the ranges of 99.38%-100.91%and 96.39%-103.50%for vinca alkaloids and Uncaria alkaloids,respectively.Furthermore,sorbents A and B exhibited strong reusability,with RSD values≤5.32%,which were based on the peak area of the corresponding alkaloids with more than 100 injections.These results indicate that the composite POPM/COF rod-shaped monoliths are promising media as SPE sorbents for extracting trace compounds in complex biological samples.

2D/2D S-scheme heterojunction with a covalent organic framework and g-C_(3)N_(4) nanosheets for highly efficient photocatalytic H2 evolution

The fabrication of S-scheme heterojunctions with fast charge transfer and good interface contacts,such as intermolecularπ–πinteractions,is a promising approach to improve photocatalytic performance.A unique two-dimensional/two-dimensional(2D/2D)S-scheme heterojunction containing TpPa-1-COF/g-C_(3)N_(4) nanosheets(denoted as TPCNNS)was developed.The established maximum interfacial interaction between TpPa-1-COF NS and g-C_(3)N_(4) NS may result in aπ–πconjugated heterointerface.Furthermore,the difference in the work functions of TpPa-1-COF and g-C_(3)N_(4) results in a large Fermi level gap,leading to upward/downward band edge bending.The spontaneous interfacial charge transfer from g-C_(3)N_(4) to TpPa-1-COF at theπ–πconjugated interface area results in the presence of a built-in electric field,according to the charge density difference analysis based on density functional theory calculations.Such an enhanced built-in electric field can efficiently drive directional charge migration via the S-scheme mechanism,which enhances charge separation and utilization.Thus,an approximately 2.8 and 5.6 times increase in the photocatalytic hydrogen evolution rate was recorded in TPCNNS-2(1153μmol g^(-1) h^(-1))compared to pristine TpPa-1-COF and g-C_(3)N_(4) NS,respectively,under visible light irradiation.Overall,this work opens new avenues in the fabrication of 2D/2Dπ–πconjugated S-scheme heterojunction photocatalysts with highly efficient hydrogen evolution performance.

Amorphous nickel-cobalt bimetal-organic framework nanosheets with crystalline motifs enable efficient oxygen evolution reaction: Ligands hybridization engineering

Development of high-efficiency and low-cost electrocatalyst for oxygen evolution reaction(OER) is very important for use at alkaline water electrolysis.Metal-organic frameworks(MOF) provide a rich platform for designing multi-functional materials due to their controllable composition and ultra-high surface area.Herein,we report our findings in the development of amorphous nickel-cobalt bimetal-organic framework nanosheets with crystalline motifs via a simple "ligands hybridization engineering" strategy.These complexes' ligands contain inorganic ligands(H_2 O and NO_3) and organic ones,hexamethylenetetramine(HMT).Further,we investigated a series of mixed-metal with multi-ligands materials as OER catalysts to explore their possible advantages and features.It is found that the Ni doping is an effective approach for optimizing the electronic configuration,changing lattice ordering degree,and thus enhancing activities of HMT-based electrocatalysts.Also,the crystalline-amorphous boundaries of various HMTbased electrocatalyst can be easily controlled by simply changing amounts of Ni-precursor added.As a result,the optimized ultrathin(Co,0.3 Ni)-HMT nanosheets can reach a current density of 10 mA cm^(-2)at low overpotential of 330 mV with a small Tafel slope of 66 mV dec^(-1).Our findings show that the electronic structure changes induced by Ni doping,2 D nanosheet structure,and MOF frameworks with multiligands compositions play critical roles in the enhancement of the kinetically sluggish electrocatalytic OER.The present study emphasizes the importance of ligands and active metals via hybridization for exploring novel efficient electrocatalysts.

Imide-based covalent organic framework with excellent cyclability as an anode material for lithium-ion battery

Covalent organic frameworks(COFs)exhibiting reversible redox behaviors have been identified as promising candidates for constructing electrode materials in lithium-ion batteries(LIBs).However,their extensive application has been limited due to finite redox sites and poor structural stability.In this study,we design and synthesize a novel polyimide covalent organic framework(PI-COF)using the traditional solvothermal method and successfully apply it as an anode material for LIBs.The large conjugated structure of PI-COF accelerates charge transfer,while its large surface area provides more active sites,making PI-COF an attractive anode material for LIBs.Furthermore,the PI-COF anode material demonstrates high reversible specific capacity and excellent long-term cycling stability due to its COF characteristics.Specifically,the PI-COF electrodes deliver a specific capacity of 800 m Ah/g at a current density of 200 m A/g after 200 cycles,while a specific capacity of 450 m Ah/g at a current density of 1000 m A/g is sustained after 800 cycles.The outstanding lithium storage capacity,particularly the satisfactory long-term cycling stability,establishes PI-COF as a promising material for LIBs.

Rational design of new in situ reduction of Ni(II)catalytic system for low-cost and large-scale preparation of porous aromatic frameworks

Porous aromatic framework 1(PAF-1)is an extremely representative nanoporous organic framework owing to its high stability and exceptionally high surface area.Currently,the synthesis of PAF-1 is catalyzed by the Ni(COD)2/COD/bpy system,suffering from great instability and high cost.Herein,we developed an in situ reduction of the Ni(II)catalytic system to synthesize PAF-1 in low cost and high yield.The active Ni(0)species produced from the NiCl_(2)/bpy/NaI/Mg catalyst system can effectively catalyze homocoupling of tetrakis(4-bromophenyl)methane at the room temperature to form PAF-1 with high Brunauer-Emmett-Teller(BET)-specific surface area up to 4948 m^(2) g^(−1)(Langmuir surface area,6785 m2 g−1).The possible halogen exchange and dehalogenation coupling mechanisms for this new catalytic process in PAF's synthesis are discussed in detail.The efficiency and universality of this innovative catalyst system have also been demonstrated in other PAFs'synthesis.This work provides a cheap,facile,and efficient method for scalable synthesis of PAFs and explores their application for high-pressure storage of Xe and Kr.

Theoretical studies of two-dimensional structure design and topological electronic properties of organic Dirac materials

Owing to the significant development in graphene,an increasing number of studies have been conducted to identify novel two-dimensional(2D)organic materials with Dirac cones and topological properties.Although a series of toy models based on specific lattice patterns has been proposed and demonstrated to possess a Dirac cone,realistic materials corresponding to the lattice models must be identified to achieve excellent properties for practical applications.To understand factors contributing to the rarity of 2D organic Dirac materials and provide guidance for identifying novel organic Dirac systems,we review recent theoretical studies pertaining to various 2D Dirac models and their corresponding organic Dirac materials,including the Haldane,Kagome,Libe,linecentered honeycomb,and Cairo pentagonal models.Subsequently,the corresponding structural and topological electronic properties are summarized.Additionally,we investigate the relationship between the existence of Dirac cones and their structural features,as well as the manner by which Dirac points emerge and propagate in these systems.

Metal–organic compounds as promising anode materials for potassium ion batteries: A mini review

Potassium-ion batteries(PIBs)represent one of the most promising alternatives to lithium-ion batteries(LIBs),owing to their exceptional attributes such as high voltages,potent power capabilities,and cost-effectiveness.Nonetheless,challenges arise from the sluggish kinetics and significant volume expansion observed during the insertion/extraction of large-radii potassium ions,leading to subpar rate performance and considerable capacity degradation in potassium-ion batteries.Consequently,it becomes imperative to explore advanced anode materials exhibiting high electrochemical activity and robust structural stability.In this regard,the present review focuses on recent progress in metal-organic compounds(MOCs)as anode materials for potassium-ion batteries,systematically discussing their outstanding merits from the perspective of metal speciation.Additionally,the principal mechanism of K ion storage within relevant MOCs is presented.Furthermore,a comprehensive summary of existing drawbacks that hinder the broader application of MOCs-based materials is provided,along with proposed guidelines and strategies for addressing the inferior performance characteristics.This review serves to illuminate the development of MOCs-based anode materials for potassium-ion batteries and offers a valuable reference for future research endeavors.

Amide-linked covalent organic frameworks as efficient heterogeneous photocatalysts in water

Semiconductor photocatalysts play an indispensable role in the photocatalytic process.Two-dimensional covalent organic frameworks(2D-COFs),as a kind of innovative photocatalyst,have garnered tremendous attention.Herein,we report an amide-linked 2D-COF(COF-JLU19)with outstanding photocatalytic performance in water,designed through a multi-synergistic approach.The synergistic effects of the high porosity,photoactive framework,high wettability,and stability of COF-JLU19 led to an unprecedented enhancement in the photocatalytic activity and recyclability in water upon illumination by visible light.More importantly,amide-linked 2D-COF based electrospinning membranes were prepared,which also exhibited superior photocatalytic activity for the degradation of Rhodamine B in water with sunlight.This study highlights the potential of the multi-synergistic approach as a universal rule for developing COF-based photocatalysts to address environmental and energy challenges.

Industrial Outlook on Zeolites and Metal Organic Frameworks

水晶的 nanoporous 材料在工业化学服务众多的枢轴的功能。他们为工业应用程序提供关键特征，例如高表面区域，一致的孔，互连的毛孔 / 隧道系统，可存取的毛孔卷，高吸附能力，离子交换能力，提高的催化活动，和形状 / 尺寸选择。作为 nanoporous 材料的一个生长得很好的家庭，沸石具有为化学、石油化学的工业的重要重要性。多孔的材料的一个新兴的班叫了器官的框架(MOF ) 也在各种各样的应用为诺言提供的金属。沸石和 MOF 能在为我们的工业化社会的未来是批评的地里起重要作用。在为原料变化的探索，沸石用作向基础化学药品提供要求的形状 / 尺寸选择的催化剂。在转移进象氢那样的另外的交通燃料的全球努力， MOF 用作精力存储媒介。在对环境污染的战斗，沸石不仅参加有害物质的俘获和消退，而且为许多工业过程提供环境地良性的选择。在这评论，为现在和将来的应用的沸石和 MOF 的合成和利用上的一个工业观点被介绍。

Plasma-assisted Co/Zr-metal organic framework catalysis of CO_(2)hydrogenation:influence of Co precursors

In this study,Co/Zr-metal organic framework(MOF)precursors were obtained by a roomtemperature liquid-phase precipitation method and the equivalent-volume impregnation method,respectively,using a Zr-MOF as the support,and Co/Zr-MOF-M and Co/Zr-MOF-N catalysts were prepared after calcination in a hydrogen-argon mixture gases(VAr:V_(H_(2))=9:1)at 350℃for 2 h.The catalytic activities of the prepared samples for CO_(2)methanation under atmosphericpressure cold plasma were studied.The results showed that Co/Zr-MOF-M had a good synergistic effect with cold plasma.At a discharge power of 13.0 W,V_(H_(2)):VCO_(2)=4:1 and a gas flow rate of 30 ml·min^(-1),the CO_(2)conversion was 58.9%and the CH4 selectivity reached 94.7%,which was higher than for Co/Zr-MOF-N under plasma(CO_(2)conversion 24.8%,CH4 selectivity 9.8%).X-ray diffraction,scanning electron microscopy,transmission electron microscopy,N_(2)adsorption and desorption(Brunauer-Emmett-Teller)and x-ray photoelectron spectroscopy analysis results showed that Co/Zr-MOF-M and Co/Zr-MOF-N retained a good Zr-MOF framework structure,and the Co oxide was uniformly dispersed on the surface of the Zr-MOF.Compared with Co/Zr-MOF-N,the Co/Zr-MOF-M catalyst has a larger specific surface area and higher Co^(2+)/Cototaland Co/Zr ratios.Additionally,the Co oxide in Co/ZrMOF-M is distributed on the surface of the Zr-MOF in the form of porous particles,which may be the main reason why the catalytic activity of Co/Zr-MOF-M is higher than that of Co/ZrMOF-N.

Covalent organic frameworks as electrode materials for rechargeable metal-ion batteries

Covalent organic frameworks(COFs),as a class of crystalline porous polymers,featuring designable structures,tunable frameworks,well-defined channels,and tailorable functionalities,have emerged as promising organic electrode materials for rechargeable metal-ion batteries in recent years.Tremendous efforts have been devoted to improving the electrochemical performance of COFs.However,although significant achievements have been made,the electrochemical behaviors of developed COFs are far away from the desirable performance for practical batteries owing to intrinsic problems,such as poor electronic conductivity,the trade-off relationship between capacity and redox potential,and unfavorable micromorphology.In this review,the recent progress in the development of COFs for rechargeable metal-ion batteries is presented,including Li,Na,K,and Zn ion batteries.Various research strategies for improving the electrochemical performance of COFs are summarized in terms of the molecular-level design and the material-level modification.Finally,the major challenges and perspectives of COFs are also discussed in the aspect of large-scale production and electrochemical performance improvements.