Post-synthetic modified MOF for Sonogashira cross-coupling and Knoevenagel condensation reactions

Advanced Porous Aromatic Frameworks: A Comprehensive Overview of Emerging Functional Strategies and Potential Applications

Porous aromatic frameworks (PAFs) are a fundamental group of porous materials characterized by their distinct structural features and large surface areas. These materials are synthesized from aromatic building units linked by strong carbon-carbon bonds, which confer exceptional rigidity and long-term stability. PAFs functionalities may arise directly from the intrinsic chemistry of their building units or through the postmodification of aromatic motifs using well-defined chemical processes. Compared to other traditional porous materials such as zeolites and metallic-organic frameworks, PAFs demonstrate superior stability under severe chemical treatments due to their robust carbon-carbon bonding. Even in challenging environments, the chemical stability and ease of functionalization of PAFs demonstrate their flexibility and specificity. Research on PAFs has significantly expanded and accelerated over the past decade, necessitating a comprehensive overview of key advancements in this field. This review provides an in-depth analysis of the recent advances in the synthesis, functionalization, and dimensionality of PAFs, along with their distinctive properties and wide-ranging applications. This review explores the innovative methodologies in PAFs synthesis, the strategies for functionalizing their structures, and the manipulation of their dimensionality to tailor their properties for specific potential applications. Similarly, the key application areas, including batteries, absorption, sensors, CO2 capture, photo-/electrocatalytic usages, supercapacitors, separation, and biomedical are discussed in detail, highlighting the versatility and potential of PAFs in addressing modern scientific and industrial challenges.

NB. Highly efficient CdS/CeO2/Ag3PO4 nanocomposite as novel heterogenous catalyst for Knoevenagel condensation and acetylation reactions

In light of environmental and economic concerns, the use of heterogeneous catalysts that can function under gentler reaction conditions has recently become popular. In this study by using the precipitation method, CdS/CeO2/Ag3PO4 ternary nanocomposites with varied molar proportions of CdS:CeO2/Ag3PO4 were produced. The catalysts' surface functional groups; morphology and crystal structures were examined using FTIR, SEM-EDX and XRD respectively. The catalytic efficiency of all synthesized nanomaterials was tested on a model Knoevenagel condensation reaction. For the best catalyst, selected from the screening, the optimization of reaction conditions such as the solvent, catalyst load, concentration of reagents such as malononitrile/acetic anhydride, and temperature. The ternary nanocomposite CdS/CeO2/Ag3PO4 (4:1) displayed higher catalytic activity (95.4 ± 3.2 %) than the rest of the nanomaterials prepared. Thus, the ternary nanocomposite CdS/CeO2/Ag3PO4 with 4:1 mol ratio with optimized reaction conditions was used to check the substrate scope of Knoevenagel condensation and acetylation reaction. The synthesized Knoevenagel condensation and acetylation reaction products were also characterized by proton and carbon NMR for their structure determination. The nanocomposite's reusability was carried out and only 7.5 ± 2 % decrement was witnessed after four runs and 23.3 % after the fifth run. and this indicates the potential application of the catalyst to organic reactions. Furthermore, we have proposed the possible catalytic mechanisms for both organic reactions.

A facile, rapid procedure for Knoevenagel condensation reaction catalyzed by efficient amino-bifunctional frameworks under mild conditions

A series of bifunctional hexagonal MOFs have been successfully constructed by the introduction of various amine functional groups within the unsaturated Cu-based MOF, HKUST, to access amino-modified frameworks. The prepared compounds are cost-effective and display high chemical and thermal stability. They were effectually exploited as efficacious and superb heterogeneous catalysts in rapid and facile Knoevenagel condensation reactions for a variety of substrates containing different electron-donating and electron-withdrawing substituents with very high conversion, good reusability under mild conditions, and very short reaction time. The contaminant presence of Lewis acid and basic sites resulted in efficient condensation reactions by the prepared catalysts.

Nanoporous {Y2}-Organic Frameworks for Excellent Catalytic Performance on the Cycloaddition Reaction of Epoxides with CO2 and Deacetalization-Knoevenagel Condensation

Stable metal-organic frameworks containing periodically arranged nanosized pores and active Lewis acid-base active sites are considered as ideal candidates for efficient heterogeneous catalysis. Herein, the exquisite combination of [Y₂(CO₂)₇(H₂O)₂] cluster (abbreviated as {Y₂}) and multifunctional linker of 2,4,6-tri(2,4-dicarboxyphenyl)pyridine (H₆TDP) led to a nanoporous framework of {[Y₂(TDP)(H₂O)₂]·5H₂O·4DMF}_n (NUC-53, NUC = North University of China), which is a rarely reported binuclear three-dimensional (3D) framework with hierarchical tetragonal-microporous (0.78 nm) and octagonal-nanoporous (1.75 nm) channels. The inner walls of these channels are aligned by {Y₂} clusters and plentifully coexisted Lewis acid-base sites of Y^III ions and N_pyridine atoms. Furthermore, NUC-53 has a quite large void volume of ∼65.2%, which is significantly higher than most documented 3D rare-earth-based MOFs. The performed catalytic experiments exhibited that activated NUC-53 showed a high catalytic activity on the cycloaddition reactions of CO₂ with styrene oxide under mild conditions with excellent turnover number (TON: 1980) and turnover frequency (TOF: 495 h^-1). Moreover, the deacetalization-Knoevenagel condensation reactions of benzaldehyde dimethyl acetal and malononitrile could be efficiently prompted by the heterogeneous catalyst of NUC-53. These findings not only pave the way for the construction of nanoporous MOF based on rare-earth clusters with a variety of catalytic activities but also provide some new insights into the catalytic mechanism.

Metal–organic framework (MOF)-, covalent-organic framework (COF)-, and porous-organic polymers (POP)-catalyzed selective C–H bond activation and functionalization reactions

The review summarizes the state-of-the-art of C–H active transformations over crystalline and amorphous porous materials as new emerging heterogeneous (photo)catalysts.

N-Heterocyclic carbenes and their precursors in functionalised porous materials

Though N-heterocyclic carbenes (NHCs) have emerged as diverse and powerful discrete functional molecules in pharmaceutics, nanotechnology, and catalysis over decades, the heterogenization of NHCs and their precursors for broader applications in porous materials, like metal-organic frameworks (MOFs), porous coordination polymers (PCPs), covalent-organic frameworks (COFs), porous organic polymers (POPs), and porous organometallic cages (POMCs) was not extensively studied until the last ten years. By de novo or post-synthetic modification (PSM) methods, myriads of NHCs and their precursors containing building blocks were designed and integrated into MOFs, PCPs, COFs, POPs and POMCs to form various structures and porosities. Functionalisation with NHCs and their precursors significantly expands the scope of the potential applications of porous materials by tuning the pore surface chemical/physical properties, providing active sites for binding guest molecules and substrates and realizing recyclability. In this review, we summarise and discuss the recent progress on the synthetic methods, structural features, and promising applications of NHCs and their precursors in functionalised porous materials. At the end, a brief perspective on the encouraging future prospects and challenges in this contemporary field is presented. This review will serve as a guide for researchers to design and synthesize more novel porous materials functionalised with NHCs and their precursors.

Retracted: Two Cu(II) coordination polymers: Heterogeneous catalytic Knoevenagel condensation reaction and treatment activity on atherosclerosis via regulating the expression of the COX-2 in vascular endothelial cells

By altering auxiliary nitrogen-donor ligands, two novel coordination polymers (CPs) containing Cu(II) formulated as [Cu2.5(L)(trz)2(H2O)2]·2H2O (1) (Htrz = 1,2,4-triazole and H3L = 5-(4-carboxybenzyloxy)isophthalic acid) and [Cu(HL)(Hbiz)] (2, Hbiz = benzimidazole) have been produced under the hydrothermal conditions. The complex 2 with both acidic and basic sites was investigated as heterogeneous catalyst, which reveals highly efficient catalytic property of the Knoevenagel condensation reaction. Dynamic changes of coagulation parameters during atherosclerosis was also explored via detecting activated partial thromboplastin time (APTT) and prothrombin time (PT), and the results showed that compared with CP 2, CP 1 has a stronger improvement on the coagulation parameters during atherosclerosis. Then, the high-sensitivity C-reactive protein and matrix metalloproteinase-1 released by the atherosclerotic segment was detected with enzyme linked immunosorbent assay (ELISA) detection, which also revealed that CP 1 could obviously decrease the inflammatory mediator released by the atherosclerotic segment, but not CP 2. And, the cyclooxygenase-2 (COX-2) relative expression level in vascular endothelial cells was detected via the real time RT-PCR. The results of the real time reverse transcription-polymerase chain reaction (RT-PCR) indicated that CP 1 has stronger activity on inhibiting the Notch signaling pathway than CP 2. Finally, we got this information, CP 1 has excellent application values on the coagulation parameters during atherosclerosis via regulating the expression of the COX-2 in vascular endothelial cells.

Synthesis of benzylidenemalononitrile by Knoevenagel condensation through monodisperse carbon nanotube-based NiCu nanohybrids

Monodisperse nickel/copper nanohybrids (NiCu@MWCNT) based on multi-walled carbon nanotubes (MWCNT) were prepared for the Knoevenagel condensation of aryl and aliphatic aldehydes. The synthesis of these nanohybrids was carried out by the ultrasonic hydroxide assisted reduction method. NiCu@MWCNT nanohybrids were characterized by analytical techniques such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM), and Raman spectroscopy. According to characterization results, NiCu@MWCNT showed that these nanohybrids form highly uniform, crystalline, monodisperse, colloidally stable NiCu@MWCNT nanohybrids were successfully synthesized. Thereafter, a model reaction was carried out to obtain benzylidenemalononitrile derivatives using NiCu@MWCNT as a catalyst, and showed high catalytic performance under mild conditions over 10-180 min.

The crystal structure of 1-benzyl-2-((4-(tert-butyl)phenyl)ethynyl)pyridin-1-ium bromide,C24H24BrN

C24H24BrN, orthorhombic, P21/n (no. 14), a = 9.875(6) Å, b = 10.415(6) Å, c = 20.562(12) Å, β = 98.130(7)°, V = 2094(2) Å3, Z = 4, R gt(F) = 0.0367, wR ref(F 2) = 0.1044, T = 273(2) K.

Composites of Palladium-Nickel Alloy Nanoparticles and Graphene Oxide for the Knoevenagel Condensation of Aldehydes with Malononitrile

Herein, we have described uniformly dispersed palladium-nickel nanoparticles furnished on graphene oxide (GO-supported PdNi nanoparticles) as a powerful heterogeneous nanocatalyst for the promotion of Knoevenagel reaction between malononitrile and aromatic aldehydes under mild reaction conditions. The successful characterization of PdNi nanoparticles on the GO surface was shown by X-ray diffraction, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy (HR-TEM), and TEM. GO-supported PdNi nanoparticles, which are used as highly efficient, stable, and durable catalysts, were used for the first time for the Knoevenagel condensation reaction. The data obtained here showed that the GO-supported PdNi nanocatalyst had a unique catalytic activity and demonstrated that it could be reused five times without a significant decrease in the catalytic performance. The use of this nanocatalyst results in a very short reaction time under mild reaction conditions, high recyclability, excellent catalytic activity, and a straightforward work-up procedure for Knoevenagel condensation of malononitrile and aromatic aldehydes.

An NHC-CuCl functionalized metal-organic framework for catalyzing β-boration of α,β-unsaturated carbonyl compounds

A microporous metal-organic framework functionalized with in situ generated NHC-CuCl units (1) has been successfully synthesized from a novel imidazolium-containing ligand. In particular, the MOF 1 can catalyze β-boration of α,β-unsaturated carbonyl compounds, while the isoreticular version of 1 (1-im) modified with only imidazolium moiety cannot. This work demonstrates for the first time the heterogeneous catalysis of NHC-Cu(i)Cl within a MOF solid.

One-Pot Synthesis of Core–Shell Structured Metal–Organic Coordination Polymer Microspheres with a Hierarchical Microporous–Mesoporous–Macroporous Structure

New core–shell structured metal–organic coordination polymer (CP) microspheres with a hierarchical microporous–mesoporous–macroporous structure are synthesized by a one-pot template-free method. The ligand L with a Schiff-base functional group is obtained by reacting 3-hydroxy-4-aminobenzoic acid with para-benzaldehyde. The coordination polymer microspheres (Zn-L-CP) are obtained by mixing the ligand L and zinc nitrate hexahydrate together under hydrothermal conditions. The resultant coordination polymer microspheres with a core–shell structure are characterized by FT-IR and solid state NMR spectroscopy, transmission and scanning electron microscopy, and nitrogen adsorption–desorption measurements. The obtained Zn-L-CP microspheres are proved to be effective heterogeneous catalysts for the deacetylation reaction with the merits of easy recycling and stability. The yield is 96% when using methanol as solvent, and the yield can remain at 90% after seven cycles.

Recyclable and Reusable Heteroleptic Nickel Catalyst Immobilized on Metal-Organic Framework for Suzuki-Miyaura Coupling

Metal-organic frameworks (MOFs) provide highly versatile platforms to stabilize molecular catalysts that are not readily accessible under homogeneous conditions, thus enabling access to a new set of catalytic materials. Herein, we describe a recyclable and highly active nickel catalyst immobilized on MOF for Suzuki-Miyaura coupling reaction, which operates under mild conditions. This mixed ligand catalyst forms from the combination of 1 equiv of MOF-immobilized ligand, 1 equiv of nickel source, and 1 equiv of PPh₃. The nature of the catalyst was verified through a series of analytical tests and catalysis experiments. The immobilized catalyst was reusable for at least up to 7 cycles without decrease in the yield of the coupled product. We also verified that this reaction does not work under homogeneous conditions and that the reaction is truly heterogeneous through "hot filtration" experiments. We identified that the reaction is first order in arylborane concentration and negative order in arylbromide concentration through the effect of substrate concentrations on the initial rate. This informed us to conduct the catalysis under slow addition of the arylbromide and reduce the catalyst loading to 1% from 3%, without detriment to the yield or rate of the reaction. The catalyst gave good to excellent isolated yields with a range of functionalities, including heterocycles on aryl bromide with widely varying electronic properties.

Cationic nickel metal-organic frameworks for adsorption of negatively charged dye molecules

Industrial dye effluents with low biodegradability are highly toxic and carcinogenic on both human and aquatic lives, thus they are detrimental to the biodiversity of environment. Herein, this data set presents the potential of cationic Nickel based MOFs in the adsorption of charged and neutral dye molecules. Data set include a concise description of experimental conditions for the synthesis of imidazolium ligands, 1,3-bis(4-carboxyphenyl)imidazolium chloride (H₂L⁺Cl⁻) and 1,3-bis(3,5-dicarboxyphenyl)imidazolium chloride (H₄L⁺Cl⁻), and MOFs. The data show that the two Nickel MOFs, 1 and 2, synthesized from imidazolium ligands are cationic frameworks. The adsorption and analysis data show that the cationic MOFs exhibit efficient adsorptive removal capacity for positively charged dyes, adsorbing up to 81.08% and 98.65% of Methyl orange and Congo red, respectively.