Reticular Framework Research Articles

Structural optimization on heat transfer characteristics in polyurethane foam film melting process by deflagration method

Flexible polyurethane foam (FPUF) is extensively utilized in various industrial sectors, due to its distinctive porosity. The deflagration approach is a prevalent method employed to reticulate polyurethane foam. The open porosity of the polymer, along with its reticular framework, significantly shape the structure of FPUF and consequently impact its mechanical properties. This study investigates the impacts of two pivotal parameters, pore size and film thickness, on the open porosity of the foam film. The heat transfer characteristics are studied by standard k-ε model coupling with the melting-solidification model based on the enthalpy-porosity method analysis model, and nine PUF models are selected as the evaluation objects. The experimental results indicate that the reticulation effect is more favorable when the open porosity ranges from 0.7 to 0.85. Based on these findings, the parameters with large variation degrees have a greater influence on the melting process of FPUF film. Furthermore, FPUF composites characterized by thicker films and smaller pores demonstrate a remarkable reticulation performance. The insights garnered from this study hold promise for advancing the comprehension of the underlying mechanisms governing FPUF deflagration, thereby facilitating the optimization of its structural applications in industrial domains.

UCS and microscopic experimental study of coconut coir fiber-waterborne epoxy resin composite modified calcium sand

To address the issues of high porosity and low strength in calcium sand of artificial islands, this study focuses on improving the calcium sand’s mechanical properties. The effects of WER curing methods and coconut fiber modification on the UCS and microscopic mechanisms of calcium sand are investigated. The results indicate that both fiber incorporation and the increase in WER ratio can enhance the unconfined compressive strength of calcareous sand, with the addition of a certain amount of coconut coir fiber showing a more significant strength increase. The optimal recommended dosage of WER is 15%, which results in an UCS of 1218 kPa, an increase of nearly 4.27 times compared to 9% WER dosage. Coconut coir fiber has good tensile strength that can improve the compressive strength of calcareous sand after curing. The UCS of calcareous sand cured with a fiber content of 0.3% to 0.5% is increased by 1247 kPa to 1792 kPa compared to cured soil with no fiber. The strong binding nature of WER addresses the issue of large porosity in calcareous sand. Together with the penetrating coconut coir fibers, it forms a three-dimensional reticular framework structure, thereby enhancing the compressive performance of the calcareous sand-cured soil mass.

Enzyme-Immobilized Porous Crystals for Environmental Applications.

Developing efficient technologies to eliminate or degrade contaminants is paramount for environmental protection. Biocatalytic decontamination offers distinct advantages in terms of selectivity and efficiency; however, it still remains challenging when applied in complex environmental matrices. The main challenge originates from the instability and difficult-to-separate attributes of fragile enzymes, which also results in issues of compromised activity, poor reusability, low cost-effectiveness, etc. One viable solution to harness biocatalysis in complex environments is known as enzyme immobilization, where a flexible enzyme is tightly fixed in a solid carrier. In the case where a reticular crystal is utilized as the support, it is feasible to engineer next-generation biohybrid catalysts functional in complicated environmental media. This can be interpreted by three aspects: (1) the highly crystalline skeleton can shield the immobilized enzyme against external stressors. (2) The porous network ensures the high accessibility of the interior enzyme for catalytic decontamination. And (3) the adjustable and unambiguous structure of the reticular framework favors in-depth understanding of the interfacial interaction between the framework and enzyme, which can in turn guide us in designing highly active biocomposites. This Review aims to introduce this emerging biocatalysis technology for environmental decontamination involving pollutant degradation and greenhouse gas (carbon dioxide) conversion, with emphasis on the enzyme immobilization protocols and diverse catalysis principles including single enzyme catalysis, catalysis involving enzyme cascades, and photoenzyme-coupled catalysis. Additionally, the remaining challenges and forward-looking directions in this field are discussed. We believe that this Review may offer a useful biocatalytic technology to contribute to environmental decontamination in a green and sustainable manner and will inspire more researchers at the intersection of the environment science, biochemistry, and materials science communities to co-solve environmental problems.

Tailoring Electrochemical Water Oxidation Activity from the Isostructural Series of Alkaline‐Stable Bimetallic Fe,Ni‐Azolate Metal–Organic Frameworks

AbstractIncorporating electrocatalytic active sites into the reticular framework allows for the design of novel catalytic structures promoting desired catalytic reactions with efficient mass transfer. However, to fully exploit the advantages of such a framework, it is crucial to ensure the electrochemical stability of the material. In this context, alkaline‐stable bimetallic MxNi2‐xCl2BTDD (M = Fe, Co) metal–organic frameworks (MOFs) are employed as electrocatalysts for alkaline water oxidation reaction (WOR) to understand the correlation between secondary metal incorporation and catalytic activity changes. For a specific Fe ratio within the MOF, the optimal catalytic activity is achieved at an overpotential of 315 mV at a WOR current density of 10 mA cm−2geo. Based on its well‐defined crystal structure and uniformly arranged metal nodes, which are not limited to specific facets, the cooperative electrocatalytic mechanism during the faradaic WOR process is investigated through operando Raman spectroscopy and density functional theory calculations. These results enable the interpretation of the electrochemical WOR mechanism based on MOF, providing a further fundamental understanding of electrocatalytic activity in bimetallic systems.

Recent progress on charge transfer engineering in reticular framework for efficient electrochemiluminescence.

Electrochemiluminescence (ECL) is a luminescence production technique triggered by electrochemistry, which has emerged as a powerful analytical technique in bioanalysis and clinical diagnosis. During ECL, charge transfer (CT) is an important process between electrochemical excitation and luminescent emission, and dramatically affects the efficiency of exciton generation, playing a pivotal role in the light-emitting properties of nanomaterials. Reticular framework materials with intramolecular/intermolecular interactions offer a promising platform for regulating CT pathways and enhancing luminescence efficiency. Deciphering the role of intramolecular/intermolecular CT processes in reticular framework materials allows for the targeted design and synthesis of emitters with precisely controlled CT properties. This sheds light on the microscopic mechanisms of electro-optical conversion in ECL, propelling advancements in their efficiency and breakthrough applications. This mini-review focuses on recent advancements in engineering CT within reticular frameworks to boost ECL efficiency. We summarized strategies including intra-reticular charge transfer, CT between the metal and ligands, and CT between guest molecules and frameworks within reticular frameworks, which holds promise for developing next-generation ECL devices with enhanced sensitivity and light emission.

Immobilization of metal active centers in reticular framework materials for photocatalytic energy conversion

To enhance the economy and society's sustainability, prioritizing innovative, green energy conversion methods is essential.

The role of reticular chemistry in photoenzymatic reaction

Photoenzymatic catalysis faces challenges like low stability and recyclability. Reticular framework materials offer solutions by enabling enzyme protection and reuse. This review highlights recent advances, design strategies, and future directions.

Electron-rich active sites created by fine-tuning the electronic structure of Co(II) porphyrin frameworks for high-performance CO2 electroreduction

Electrochemical reduction of CO2 for sustainable production of carbon-based chemicals and fuels is a promising approach to solve environmental and energy problems. However, the development of electrocatalysts with satisfactory catalytic activity and product selectivity is still a considerable challenge. Porphyrin organic frameworks (POFs) are considered one of the most promising models for regulating the structure at the molecular level. In this work, we propose a strategy that integrates nanoscale and molecular scale to synthesize several organic-inorganic composite materials by the template-oriented polymerization of isolated Co(II) porphyrin (CoPor-) on the carbon nanotube (CNT) scaffold. The electronic structure of CoPor-active sites in the POFs for electrocatalytic CO2 reduction was tuned by modification of the substituents. Remarkably, the optimal sample CoPOF-(Me)4@CNT was found to reduce CO2 to CO with a high Faradaic efficiency for CO production (FECO) of 93 % at the overpotential of 600 mV and a remarkable turnover frequency (TOF) value of 9720 h−1 at −1.0 V vs reversible hydrogen electrode (RHE), surpassing the performance of most recently reported CoPOFs in terms of selectivity and efficiency. Moreover, this electrocatalyst is stable for more than 42 h without a loss in reactivity. In-depth experimental research suggests that the electron-rich active sites created by methyl substituents with an electron-donating effect and the synergy between POF nanolayers and CNT scaffold successfully modulate the electronic structure of Co sites in this reticular framework, thereby enhancing the electrocatalytic performance.

Construction of Thiadiazole-Linked Covalent Organic Frameworks via Facile Linkage Conversion with Superior Photocatalytic Properties.

The establishment of facile synthetic routes to engineer covalent organic frameworks (COFs) with fully conjugated structure and excellent stability is highly desired for practical applications in optoelectronics and photocatalysis. Herein, a novel linkage conversion strategy is reported to prepare crystalline thiadiazole-linked COFs via thionation, cyclization, and oxidation of N-acylhydrazole bonds with Lawesson's reagent (LR). The as-prepared thiadiazole-linked COFs not only remain porosity and crystallinity, but enhance its chemical stability. Furthermore, thiadiazole-linked COFs are more favorable to lower exciton binding energy and promote π-electron delocalization over the whole reticular framework than N-acylhydrazone-linked COFs. Notably, the extended π-conjugation structure and decent crystallinity of the resulting TDA-COF are reflected by its higher photocatalytic H2 evolution rate (61.3mmol g-1 in 5h) in comparison with that (7.5mmol g-1 ) of NAH-COF.

Reticular framework materials for photocatalytic organic reactions.

Photocatalytic organic reactions, harvesting solar energy to produce high value-added organic chemicals, have attracted increasing attention as a sustainable approach to address the global energy crisis and environmental issues. Reticular framework materials, including metal-organic frameworks (MOFs) and covalent organic frameworks (COFs), are widely considered as promising candidates for photocatalysis owing to their high crystallinity, tailorable pore environment and extensive structural diversity. Although the design and synthesis of MOFs and COFs have been intensively developed in the last 20 years, their applications in photocatalytic organic transformations are still in the preliminary stage, making their systematic summary necessary. Thus, this review aims to provide a comprehensive understanding and useful guidelines for the exploration of suitable MOF and COF photocatalysts towards appropriate photocatalytic organic reactions. The commonly used reactions are categorized to facilitate the identification of suitable reaction types. From a practical viewpoint, the fundamentals of experimental design, including active species, performance evaluation and external reaction conditions, are discussed in detail for easy experimentation. Furthermore, the latest advances in photocatalytic organic reactions of MOFs and COFs, including their composites, are comprehensively summarized according to the actual active sites, together with the discussion of their structure-property relationship. We believe that this study will be helpful for researchers to design novel reticular framework photocatalysts for various organic synthetic applications.

The regulation research of topology and magnetic exchange models of CPs through Co(II) concentration adjustment

We have designed and synthesized two new Co-CPs by modulating the concentration of cobalt ions, namely [Co3(HL)2(4,4′-bibp)3(H2O)4]n (1) and {[Co9(L)4(4,4′-bibp)4(H2O)6(μ2-OH)2]·4,4′-bibp·2H2O}n (2) (H4L ​= ​1,1′,2′,1″-terphenyl-4,4′,4″,5′-tetracarboxylic acid and 4,4′-bipb ​= ​1,4-di(pyridin-4-yl)benzene). CP 1 is a three-dimensional (3D) pillar-layered network constructed by HL3− and bridging 4,4′-bibp co-ligands with a 10-connected (424.512.68.7) topology. CP 2 is a 3D reticular framework with (4,4,5,5,6)-connected topology. The structural diversity of the two CPs suggests that the cluster numbers and the different local coordination geometries of Co(II) ions can be induced by the reaction material ratio. Focusing on the bridging system, CP 1 cnsists of centrosymmetric trinuclear octahedral cobalt(II) units, and within the units, the cobalt(II) ions are found to be ferromagnetically coupled. CP 2 cnsists of centrosymmetric nonanuclear cobalt(II) units, including five octahedral and four trigonal-bipyramidal cobalt(II) ions. Antiferromagnetic interactions are observed in the partial triangular units, and also in the other parts, showing an overall antiferromagnetic behavior.

Transformation of Covalent Organic Frameworks from N‐Acylhydrazone to Oxadiazole Linkages for Smooth Electron Transfer in Photocatalysis

AbstractCovalent organic frameworks (COFs) are regarded as new platforms for solar‐to‐chemical energy conversion due to their tailor‐made functions and pre‐designable structures. Their intrinsic reversibility and the high polarization of organic linkages inevitably result in poor chemical stability and weak optoelectronic properties. Herein, one N‐acylhydrazone‐linked COF (H‐COF) was converted into a stable and π‐conjugated oxadiazole‐linked COF via post‐oxidative cyclization. Both chemical stability and π‐electron delocalization throughout the reticular framework are significantly improved, leading to a high hydrogen evolution rate of 2615 μmol g−1 h−1 upon visible light irradiation, which is over four times higher than that of H‐COF. This work provides a facile protocol for the fabrication of π‐conjugated COFs and the modulation of photophysical properties for photocatalytic application.

Transformation of Covalent Organic Frameworks from N-Acylhydrazone to Oxadiazole Linkages for Smooth Electron Transfer in Photocatalysis.

Covalent organic frameworks (COFs) are regarded as new platforms for solar-to-chemical energy conversion due to their tailor-made functions and pre-designable structures. Their intrinsic reversibility and the high polarization of organic linkages inevitably result in poor chemical stability and weak optoelectronic properties. Herein, one N-acylhydrazone-linked COF (H-COF) was converted into a stable and π-conjugated oxadiazole-linked COF via post-oxidative cyclization. Both chemical stability and π-electron delocalization throughout the reticular framework are significantly improved, leading to a high hydrogen evolution rate of 2615 μmol g-1 h-1 upon visible light irradiation, which is over four times higher than that of H-COF. This work provides a facile protocol for the fabrication of π-conjugated COFs and the modulation of photophysical properties for photocatalytic application.

Deformation of the prefabricated monolithic cover from porous concrete reinforced with fiberglass fittings

The paper studies the properties and the possibilities of using definite size thin-walled fasciae from the lightweight concrete, reinforced with one-layer fiberglass fittings, by numerical methods. The object of the research is a standard element of the prefabricated monolithic reticular cover’s clothing under the plane stress. Plane prefabricated cells have a hexagonal shape and ribbing that make a basis for a common reticular framework after the assembly of the cover. Strength properties of the model are studied at different reinforcement degrees. The paper also researches the possibilities of increasing the fittings’ adhesion ability due to the regular curved structure. The comparison of different reinforcement variants is presented. The distributive function of the contour ribbing on the stressed state of the standard element is evaluated. The paper also gives recommendations on the use of discrete thin-walled reinforced elements as the elements of the bearings’ covers in the structure of multilayer or multilayer membranate constructions.

Accelerated Development of Colloidal Nanomaterials Enabled by Modular Microfluidic Reactors: Toward Autonomous Robotic Experimentation.

In recent years, microfluidic technologies have emerged as a powerful approach for the advanced synthesis and rapid optimization of various solution-processed nanomaterials, including semiconductor quantum dots and nanoplatelets, and metal plasmonic and reticular framework nanoparticles. These fluidic systems offer access to previously unattainable measurements and synthesis conditions at unparalleled efficiencies and sampling rates. Despite these advantages, microfluidic systems have yet to be extensively adopted by the colloidal nanomaterial community. To help bridge the gap, this progress report details the basic principles of microfluidic reactor design and performance, as well as the current state of online diagnostics and autonomous robotic experimentation strategies, toward the size, shape, and composition-controlled synthesis of various colloidal nanomaterials. By discussing the application of fluidic platforms in recent high-priority colloidal nanomaterial studies and their potential for integration with rapidly emerging artificial intelligence-based decision-making strategies, this report seeks to encourage interdisciplinary collaborations between microfluidic reactor engineers and colloidal nanomaterial chemists. Full convergence of these two research efforts offers significantly expedited and enhanced nanomaterial discovery, optimization, and manufacturing.

Triaxially Woven Hydrogen-Bonded Chicken Wires of a Tetrakis(carboxybiphenyl)ethene.

Interpenetration of low-dimensional networked structural motifs crucially affects porosity, stability, and properties of the whole reticular framework. However, varying and controlling the manner of interpenetration is still challenging. Herein, a porous hydrogen-bonded organic framework (HOF) with wvm-like weave constructed by triaxially woven chicken wires of X-shaped tetra-armed tetrakis(carboxybiphenyl)ethene CBPE, formally 4',4''',4''''',4'''''''-(ethene-1,1,2,2-tetrayl)tetrakis(1,1'-biphenyl-4-carboxylic acid), is reported. The structure is a contrast to a non-interpenetrated layered framework composed of tetrakis(4-carboxyphenyl)ethene CPE. This exotic framework of CBPE is due to the disproportionate conformation of the outer four phenylene rings in the peripheral biphenyl arms. The activated framework CBPE-1a exhibits thermal stability up to 220 °C and a BET surface area of 555 m2 g-1 . Additionally, the HOF shows mechanochromic behavior in terms of fluorescence color and quantum efficiency. The achievement of the present HOFs can provide insight into constructing a new type of functional porous organic materials with interwoven network structures.

Pseudo-5-Fold-Symmetrical Ligand Drives Geometric Frustration in Porous Metal-Organic and Hydrogen-Bonded Frameworks.

Reticular framework materials thrive on designability, but unexpected reaction outcomes are crucial in exploring new structures and functionalities. By combining "incompatible" building blocks, we employed geometric frustration in reticular materials leading to emergent structural features. The combination of a pseudo-C5-symmetrical organic building unit based on a pyrrole core with a C4-symmetrical copper paddlewheel synthon led to three distinct frameworks by tuning the synthetic conditions. The frameworks show structural features typical for geometric frustration: self-limiting assembly, internally stressed equilibrium structures, and topological defects in the equilibrium structure, which manifested in formation of a hydrogen-bonded framework, distorted and broken secondary building units, and dangling functional groups, respectively. The influence of geometric frustration on the CO2 sorption behavior and the discovery of a new secondary building unit shows geometric frustration can serve as a strategy to obtain highly complex porous frameworks.

The Chemistry of Reticular Framework Nanoparticles: MOF, ZIF, and COF Materials

AbstractNanoparticles have become a vital part of a vast number of established processes and products; they are used as catalysts, in cosmetics, and even by the pharmaceutical industry. Despite this, however, the reliable and reproducible production of functional nanoparticles for specific applications remains a great challenge. In this respect, reticular chemistry provides methods for connecting molecular building blocks to nanoparticles whose chemical composition, structure, porosity, and functionality can be controlled and tuned with atomic precision. Thus, reticular chemistry allows for the translation of the green chemistry principle of atom economy to functional nanomaterials, giving rise to the multifunctional efficiency concept. This principle encourages the design of highly active nanomaterials by maximizing the number of integrated functional units while minimizing the number of inactive components. State‐of‐the‐art research on reticular nanoparticles—metal‐organic frameworks, zeolitic imidazolate frameworks, and covalent organic frameworks—is critically assessed and the beneficial features and particular challenges that set reticular chemistry apart from other nanoparticle material classes are highlighted. Reviewing the power of reticular chemistry, it is suggested that the unique possibility to efficiently and straightforwardly synthesize multifunctional nanoparticles should guide the synthesis of customized nanoparticles in the future.

Histogenesis of spleen in foetus of surti goats

A study was conducted to elucidate the microstructural and developmental changes in the spleen of 30 Surti goat foetuses at different stages of prenatal development (from 44 to 144 days, 4.0 to 41.0 cm crownrump length; CRL). At 44 days (4.0 cm CRL), the splenic tissue was developing in close proximity to stomach. Groups of few haematopoietic cells were observed in the parenchyma of spleen at the age of 50 days (6.5 cm CRL). From 58 days (9.2 cm CRL) of gestation, reticular cells were increased in number and began to form a reticular framework around the developing arterioles. The foetal splenic parenchyma showed predominance of red pulp at the age of 63 to 64 days (11.6 to 12.2 cm CRL). At 84 days of gestation (19.0 cm CRL), white pulp appeared in the form of irregularly diffused patches of lymphoid tissue scattered among the red pulp. From 95 days (23.0 cm CRL) onwards, splenic parenchyma showed separate red and white pulp; however in Surti goat foetuses histogenesis of red and white pulps still continued even at the age of 144 days (41.0 cm CRL). The detailed knowledge about the organogenesis and histogenesis of goat foetal spleen at various stages of development may be used to assess functional status of spleen in prenatal period.

A new supramolecular compound based on Keggin-type phosphomolybates with mixed-ligand and mixed-valence Cu(I/II): [Cu(I)(phen)2]2{[Cu(II)]2(phen)4PTA}[H3PMo8VIMo4VO40

With an aim to obtain a new supramolecular compound based on Keggin-type polyoxometalates with mixed-ligand: [Cu(I)(phen)2]2{[Cu(II)]2(phen)4PTA}[H3PMoV4MoVI8O40] (phen = 1,10-phenanthroline, PTA = terephthalic acid) has been synthesized under hydrothermal conditions and structurally characterized by elemental analyses, IR, X-ray single crystal diffraction, TG analyses and XPS. In the title compound, the Keggin-type phosphomolybates anions, butterfly-shaped [Cu(I)(phen)2]+ subunits and dumbbell-shaped {[Cu(II)]2(phen)4PTA}2+ subunits are alternately connected to form chiral helical chains via hydrogen bonds along b axis, and the adjacent chiral helical chains are connected in the way of sharing butterfly-shaped [Cu(I)(phen)2]+ subunits and dumbbell-shaped {[Cu(II)]2(phen)4PTA}2+ subunits to form 3D supramolecular reticular framework. As expected, the title compound with mixed-ligands (phen and PTA) has been successfully synthesized, inconceivably, the title compound also contains mixed-valence Cu (Cu(I) in butterfly-shaped [Cu(I)(phen)2]+ subunits; Cu(II) in dumbbell-shaped {[Cu(II)]2(phen)4PTA}2+ subunits). The preliminary analyses show that mixed-valence Cu(I/II) may be due to the reduction of Cu(II) (from CuCl2) to Cu(I) (in butterfly-shaped [Cu(I)(phen)2]+ subunits) by N-containing compound. The successful results of this work provide a new idea that supramolecular materials with attractive structures and novel properties, which could be designed and synthesized by introducing of mixed-ligands into the supramolecular materials. Additionally, the electrocatalytic property of the title compound to H2O2 has been studied.