Knoevenagel Condensation Reaction Research Articles

SrCaAl mixed metal oxides derived from LDH precursor as a novel and efficient solid base catalyst for Knoevenagel condensation reaction: Multivariate optimization study

The Knoevenagel condensation reaction is one of the most important reactions in the industry for the synthesis of organic materials, medicinal, and biological compounds. In this work, we have proposed an original and efficient solid-base catalytic system for the Knoevenagel condensation reaction. For the first time, a mixed oxide catalyst derived from hydrotalcite-like Sr0.5Ca2.5Al precursor was synthesized by co-precipitation method and subsequently calcined for 5 h at 850 °C. The catalysts were characterized by various techniques. The Sr0.5Ca2.5Al mixed oxide was also compared with the usual Ca3Al sample in terms of structural characteristics and catalytic activity in the Knoevenagel reaction between active methylene compounds and benzaldehyde. The findings revealed that the Sr0.5Ca2.5Al mixed oxide sample is considerably active in this reaction compared to the Ca3Al sample due to its stronger basicity. The kinetics of the Knoevenagel condensation reaction over the Sr0.5Ca2.5Al catalyst was investigated and indicated that it follows from the second-order model. The stability and reusability of the catalyst sample were studied and it was found that the Sr0.5Ca2.5Al catalyst has high stability and a good lifetime. The effects of reaction time, amount of catalyst, and reaction temperature on benzaldehyde conversion (%) and product selectivity (%) were assessed in this study using the Box-Behnken design. The appropriateness of the quadratic regression model was evaluated through the ANOVA method. Under optimal conditions, the conversion percentage of benzaldehyde and product selectivity reached 97% and 84%, respectively.

Bmim][CF3COO] as a Solvent and a Catalyst for the Knoevenagel Condensation

Abstract: A facile and green strategy for the Knoevenagel condensation reaction of aryl aldehydes and active methylene compounds using [Bmim][CF3COO] ionic liquid as a solvent and a catalyst has been introduced. The method features some advantages, such as good to excellent yield of products, relatively short reaction time, mild reaction conditions, broad substrate scope, and scalability. Moreover, the ionic liquid solvent could be conveniently recycled and reused up to three times without any considerable loss of catalytic activity. Twelve products were obtained in high yields, and their structures were confirmed by NMR data. A plausible reaction mechanism involving the role of the ionic liquid catalyst was also suggested.

Green Method Synthesis of Magnetic Nanoparticles and its Functionalized MNPs for Knoevenagel Condensation Reaction

Background: Knoevenagel condensation is an important C-C bond formation reaction catalyzed by various homogeneous and heterogeneous acid-base catalysts. background: Knoevenagel condensation is an important C-C bond formation reaction, and employs various acid and base-catalyzed reactions of both homogeneous and heterogeneous catalysts. Method: The present work describes the eco-friendly preparation of magnetic nanoparticles Fe3O4 (MNPs) and its functionalization to Fe3O4@SiO2@SO3H. The prepared MNPs and their functionalized materials were fully characterized by FT-IR, XRD, FE-SEM, HR-TEM, and VSM. Further demonstrated application of these catalysts for the C-C bond formation reactions of Knoevenagel condensation employing special aldehyde derivatives with malononitrile at room temperature gave excellent product isolation. Results: The application of the prepared functionalized MNPs for the Knoevenagel condensation was demonstrated by the reaction of various aryl/heterocyclic and cholesterol aldehyde with malononitrile at room temperature stirring for about 30 min in ethanol solvent. The final product isolated is confirmed by various spectroscopic techniques such as FT-IR, 1H-, & 13C-NMR, and mass spectrometry. Furthermore, the selected compounds are screened for their photophysical properties, and interestingly compound 3j showed good fluorescent properties. Conclusion: Overall the present work described a greener method preparation of MNPs, and its functionalized employed as a heterogeneous catalyst for the Knoevenagel condensation of various aryl/heterocyclic and cholesterol aldehyde with malononitrile. The method developed is simple, easily separated catalyst by an external magnet, and recycled up to five cycles without any noticeable change in the final product isolation. Further, the prepared derivatives screened for their photophysical properties, and interestingly compound 3j showed good fluorescent properties.

Degradable n‐Type Organic Semiconductors Based on Knoevenagel Condensation Reaction

AbstractThe increasing amount of electronic exerts a profound impact on both the environment and human health. Looking forward, it is imperative to develop electronic products that can degrade under mind condition, which largely relies on the development of degradable organic semiconductors (OSCs). Yet, designing degradable OSCs with decent electrical properties is challenging. In this study, two degradable n‐type OSCs based on a dynamic covalent C═C bond formed via the Knoevenagel condensation reaction are reported. The cleavage of Knoevenagel formed C═C bond through a retro‐Knoevenagel process imparts the degradability of these two OSCs in the weak base, particularly in the human‐friendly α‐amino acid of lysine. Meanwhile, the C═C bond formed by Knoevenagel reaction preserves optimal backbone planarity and good electron delocalization of the molecules. This, in turn, endows the OSCs with commendable electron transport performance, achieving an electron mobility of up to 0.57 cm2 V⁻¹ s⁻¹ in organic thin‐film transistors. This work provides a new insight into the molecular design strategy for the development of OSCs with degradability and good electrical properties.

Can a Small Change in the Heterocyclic Substituent Significantly Impact the Physicochemical and Biological Properties of (Z)-2-(5-Benzylidene-4-oxo-2-thioxothiazolidin-3-yl)acetic Acid Derivatives?

Rhodanine-3-acetic acid derivatives are attractive compounds with versatile effects. What is very important is that compounds of this type have many biological properties. They are tested, among others, as fluorescent probes for bioimaging and aldose reductase inhibitors. Rhodanine-3-acetic acid derivatives also have antibacterial, antifungal and anticancer activity. The presented work demonstrates that a slight change in the five-membered heterocyclic substituent significantly affects the properties of the compounds under consideration. Three rhodanine-3-acetic acid derivatives (A-1-A-3) were obtained in the Knoevenagel condensation reaction with good yields, ranging from 54% to 71%. High thermal stability of the tested compounds was also demonstrated above 240 °C. The absorption and emission maxima in polar and non-polar solvents were determined. Then, the possibility of using the considered derivatives for fluorescence bioimaging was checked. Compounds A-1 and A-2 were successfully used as fluorescent dyes of fixed cells of mammalian origin. In addition, biological activity tests against bacteria and fungi were carried out. Our results showed that A-1 and A-2 showed the most excellent antimicrobial activity among the newly synthesized compounds, especially against Gram-positive bacteria.

Styryl-extended Azopyrroles and their boron difluoride complexes: Synthesises, structures, spectra, and DFT calculation

Three styryl-extended azopyrrole compounds (2–4) with different substituents (-H, -NO2, and -N(CH3)2) have been synthesized by Knoevenagel condensation reaction between azopyrrole and substituted benzaldehyde. Their BF2 complexes (5–7) were also synthesized. The planar structure of compound 3 was characterized by X-ray crystallographic study. Hirshfeld surface analysis reveals that van der Waals interactions and hydrogen-bonding are the dominant interactions in the crystal packing. All compounds have λmax absorption greatly red-shift even to deep-red light region (646 nm) due to the extended π-conjugation by styryl group and the introduction of BF2 group. The structures, frontier molecular orbitals (FMOs), energy gaps (ΔE) and UV–Vis spectra of these compounds were evaluated by DFT calculations. The results reveal that the styryl, electron donating and withdrawing groups, and BF2 group all can reduce the energy gap (ΔE) of the compounds, and finally cause their long-wavelength absorption.

Comprehensive understanding of base catalysis derived from nitrogen species incorporated into the frameworks of silica and carbon porous materials

A base-catalytic nitrogen site in a specific and confined nanospace on the surfaces of silica and carbon was developed using mesoporous silica SBA-15 and its replicated porous carbon nitride PCN. Knoevenagel condensation reactions using differentially active methylene compounds and diffusion studies using CO2 as the probe molecule for the basic site revealed that the primary amine-based N component showed high activity for the base-catalyzed reaction. Among the samples investigated, primary amine-grafted SBA-15 showed the highest performance owing to the activity and location density of primary amines, as well as its surrounding hydrophobic nature. Although NSBA-15 showed moderate catalytic performance owing to an isolated active N species located on its mesopore surface, methylation of the N species led to enhanced catalytic performance because of its isolation effect. Carbonaceous PCN showed high hydrophobicity and durability during reaction and storage. A general design for N-based basic catalytic materials was also proposed.

Highly sensitive fluorescence turn-OFF and reversible chemical sensor for Hg2+ ion based on pyrene appended 2-thiohydantoin

A novel fluorometric chemical sensor (PY-2TH) based on 2-thiohydantoin (2TH) in conjugation with pyrene (PY) was designed by facile one-pot Knoevenagel condensation reaction and explored for the sensitive and selective detection of Hg2+ ion in solution and solid state methods. Different analytical techniques like NMR and LC-MS concomitantly confirmed the structure of PY-2TH. Absorption and emission studies demonstrate positive solvatochromic effects indicating intramolecular charge transfer in polar solvents. PY-2TH exhibits unprecedented selectivity for detecting Hg2+ ions in tetrahydrofuran (THF) through turn-OFF fluorescence with 90% decrease in the emission intensity with a limit of detection (LOD) of ∼4.4 ppb. The mechanistic investigation through NMR and optical studies confirm the formation of a 2:1 complex between PY-2TH and Hg2+. Thin films of PY-2TH exhibits the J-aggregate formation in the solid state leading to a shift in the emission towards the near-infrared region. Further, we have demonstrated the applicability of PY-2TH for detection of Hg2+ ions and fluorescence imaging in live Zebrafish larvae and the toxicological effects are explored. Cytotoxic evaluation on Zebrafish larval cells revealed that PY-2TH is found to be non-toxic. Detailed analysis demonstrate the potential of PY-2TH for ultra-sensitive Hg2+ ion detection and removal in aqueous environments, highlighting its applicability for identification of metal contamination in live organisms and environmental toxicity.

3D-printed metal-organic framework encapsulated Keggin heteropolyacid for catalytic purpose

To address the limitations of metal-organic frameworks for large-scale applications and the challenges associated with the heterogenization of heteropolyacids, we developed a catalytic monolith leveraging the encapsulation concept and 3D-printing technology. In this approach, a Keggin-type heteropolyacid was encapsulated within a Fe-based metal-organic framework through an in-situ method and subsequently incorporated into a 3D printing ink for the fabrication of a catalytic monolith. The monolith underwent comprehensive characterization, elucidating its morphological, structural, and mechanical features. Moreover, the catalytic performance of the 3D-printed monolith was thoroughly evaluated in Knoevenagel condensation reaction, highlighting its remarkable catalytic activity and exceptional recyclability. Characterization of the recycled catalyst, along with a hot filtration test, further confirmed the stability of the catalyst, the suppression of heteropolyacid leaching, and the manifestation of true heterogeneous catalysis.

Synthesis of selenium containing quinoline probe for superoxide sensing and its anticancer activity study

Herein, we have reported the highly effective use of the Knoevenagel condensation reaction to synthesize organoselenium containing quinoline-based probe. The probe was characterized by Nuclear Magnetic Resonance and Infra-Red spectroscopy and mass spectrometry. The probe selectively detects KO2 with high sensitivity over other reactive oxygen species and biothiols. Photo-induced electron transfer process is responsible for fluorescence “turn-on” event through transformation of selenide to selenoxide. The probe reacted with KO2 in less than a second with lower detection limit (0.14μM). The probe have better anticancer potency as compared to standard drug Cisplatin.

Enzymatic Knoevenagel condensation in dual‐functionalized water‐mimicking ionic liquids and tertiary amide solvents

AbstractBACKGROUNDKnoevenagel condensation is an important tool for building carbon–carbon (CC) bonds, especially when catalyzed by enzymes to enable a potentially high chemo‐, regio‐ and/or stereoselectivity. Although many Knoevenagel condensation reactions are carried out in aqueous solutions, insoluble hydrophobic substrates often lead to poor catalytic efficiencies. The use of water‐miscible organic solvents improves the substrate solubilization, but usually induces activity suppression or inactivation of enzymes. There is a great need to develop alternative solvents for both substrate dissolution and enzyme compatibility in CC bond formation reactions.RESULTSOur group previously developed dual‐functionalized water‐mimicking ionic liquids (ILs) for the activation and stabilization of hydrolases (e.g. lipase and protease). In the present study, we evaluated the Knoevenagel condensation of 4‐chlorobenzaldehyde with acetylacetone, and found that porcine pancreas lipase in water‐mimicking ILs carrying ammonium, imidazolium and benzimidazolium cations enabled higher reaction rates (up to 3.22 μmol min−1 g−1 lipase) and better yields than tert‐butanol, glymes and [BMIM][Tf2N]. Interestingly, tertiary amide solvents such as N‐methyl‐2‐pyrrolidone (NMP), N,N‐dimethylformamide (DMF) and N,N‐dimethylacetamide (DMAc) led to 8.2‐ to 11.1‐fold increases in the initial rate (up to 35.66 μmol min−1 g−1 lipase) when compared with dual‐functionalized ILs, which is likely due to some synergistic effect of these tertiary amides with the lipase.CONCLUSIONDual‐functionalized ILs based on ammonium, imidazolium and benzimidazolium cations improved Knoevenagel condensation reaction rates and yields when compared with tert‐butanol and glymes. Tertiary amides (NMP, DMF and DMAc) significantly increased the reaction rate. © 2024 The Authors. Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI).

A novel ethylene linkage-based covalent organic framework for turn-on fluorescence sensing for Al3+ with excellent selectivity and sensitivity

Covalent organic Framework (COFs) has become a new platform for functional research and material design. A novel covalent organic framework (CN-COF) was first synthesized with p-xylylene dicyanide and 2-hydroxy-1,3,5-benzenetrialdehyde through the Knoevenagel condensation reaction. CN-COF is a porous crystal material with strong thermal and chemical stability. CN-COF exhibits a selective “turn-on” fluorescence response to Al3+ in ethanol with blue-shifted emission spectra over the other tested metal ions. The color changes from pink to earth yellow, and the fluorescence effect is clearly visible. The fluorescence intensity of CN-COF was linearly related to the concentration of Al3+, and the detection limit was 1.815 μM. Importantly, CN-COF exhibits a satisfactory recovery for detecting Al3+ in drinking water and fish samples. CN-COF also showed the intuitive semi-quantitative detection ability for Al3+ via the color change with the naked eyes. The special pore structure is conducive to allow Al3+ enter to coordinate with O and N atoms on the wall of CN-COF scaffold. The revisable fluorescence change upon the selective addition of Al3+ and XRD, EDTA, XPS and DFT results demonstrated the complex process. The inhibition of the photoinduced electron transition from O atoms to Al3+ induced the fluorescence enhancement. This study not only presents a synthesis idea for a new structural organic framework, but also offers a highly selective and sensitive fluorescence chemical sensor for the identification and detection of Al3+.

The Use of the Titanium Tetrachloride (Ticl4) Catalysts as a Reagent for Organic Synthesis

Abstract: TiCl4 is a widely utilized reagent in organic synthesis, often functioning through Lewis’s acid-promoted transformations. This review explores the potential for TiCl4 to catalyse various examples, adhering to the classic catalyst definition and allowing for the use of sub-stoichiometric quantities of the catalyst relative to the substrate. The use of metal catalysts in organic synthesis has witnessed a surge in interest due to their ability to facilitate a wide range of chemical reactions. This review article highlights the significance of titanium metal catalysts via comparison with other metal catalysts like Pd [NO3]2, IrO4, Au/Fe2O3, SnCl2, and AlCl3. Among these catalysts, titanium tetrachloride (TiCl4) has gained considerable popularity for its cost-effectiveness, eco-friendliness, enhancing reaction efficiency, and ability to accelerate reactions while reducing reaction times. This comparison helps in determining the most suitable catalyst for different chemical processes, considering efficiency, safety, and economic factors. TiCl4 operates as a non-consumable catalyst, allowing for the use of sub-stoichiometric quantities relative to the substrate. This review discusses TiCl4's applications, efficiency, and mechanisms in organic synthesis. It distinguishes itself by presenting new applications and comparative efficiencies of TiCl4, delving into detailed reaction mechanisms, and discussing its environmental, economic, and safety aspects. TiCl4's role in pivotal chemical reactions, such as Friedel-Crafts acylation and alkylation, epoxidation, cyclization, Mannich reactions, Suzuki-Miyaura reactions, Pechmann condensation, Knoevenagel condensation, anti-Markovnikov hydration, pinacol coupling, and Diels-Alder reactions. These reactions have led to the synthesis of biologically active compounds like zolmitriptan, ropinirole, risperidone, and rivastigmine. TiCl4-catalyzed reactions are characterized by their mild conditions, high efficiency, and selectivity, making them an attractive choice for modern organic cyclic, acyclic, and heterocyclic synthesis.

CuAs2O4: Design, Hydrothermal Synthesis, Crystal Structure, Photocatalytic Dye Degradation, Hydrogen Evolution Reaction, Knoevenagel Condensation Reaction, and Thermal Studies.

CuAs2O4 has been explored as a heterogeneous catalyst in the fields of photocatalysis, electrocatalysis, and solvent-free organic transformation reactions. The homogeneity has been successfully attained for the first time by designing a pH-assisted hydrothermal synthesis technique. Single-crystal X-ray diffraction studies reveal that no phase transition has been observed by lowering the temperature up to 103 K with no existence of satellite reflections. The crystal structure exhibits tetragonal symmetry with space group P42/mbc and consists of [CuO6] octahedra and [AsO3E] tetrahedra (E represents the stereochemically active lone pair). Structural investigation shows a cylindrical void inside the structure, which could lead to interesting physical and chemical properties. The photocatalytic dye degradation efficiency with methylene blue (MB) showed ∼100% degradation, though the degradation efficiency increased by 2-fold with the addition of 6% H2O2. The reusability of the catalyst up to the 10th cycle with ∼35% MB dye degradation has been established. It can exhibit HER activity with a low overpotential of 165 mV with respect to RHE to attain the current density of j = 10 mA cm-2. SEM and TEM revealed rod-shaped particles, which supported the large number of catalytic active sites. The structural consistency of the catalyst after photodegradation and HER studies is confirmed by the PXRD pattern. XPS confirms the oxidation state of Cu and As in the compound. The catalytic activity toward the Knoevenagel condensation reaction at moderate temperature under solvent-free condition is also studied. TG-DTA shows an endothermic minimum (Tmin) at 436 °C due to the mass loss of As2O3.

Carbon Dots as New Effective Catalysts for Knoevenagel Condensation Reaction and Synthesis of Cyclic Carbonates under Solvent‐free Conditions

AbstractCarbon dots (CDs) as new efficient catalysts have been developed for the Knoevenagel condensation reaction and the synthesis of cyclic carbonates under solvent‐free conditions. Six kinds of carbon dots with different numbers of amino groups were synthesized. The amine‐terminated carbon dot (NCDs‐1) was synthesized using arginine and ethylenediamine by a microwave technique, and its catalytic action was studied. NCDs‐1 with the highest numbers of amino groups was used as new metal‐free and effective heterogeneous catalysts to perform essential Knoevenagel condensation and cycloaddition reactions in solvent‐free conditions. 1H NMR was used to demonstrate the Knoevenagel condensation mechanism, in situ Fourier infrared spectroscopy was used to investigate CO2 cycloaddition and a catalytic mechanism was postulated. NCDs‐1 showed a yield of 96.3±1.5 % for Knoevenagel condensation of benzaldehyde and malononitrile. In addition, NCDs‐1/TBAB showed a yield of (97.0±1.0 %) of 4‐phenyl‐1,3‐dioxolan‐2‐one for styrene oxide at 100 °C and 0.1 MPa in 1.5 h. A simple and convenient method for catalytic reactions with amine‐terminated carbon dots was developed.

Revealing the roles of the dual active-sites on a polyoxometalate-based metal–organic framework in catalyzing Knoevenagel condensations

The efficient catalysis of Knoevenagel condensations under mild conditions is a significant way for obtaining olefin compounds, which can be used to produce a wide range of biologically active heterocyclic chemicals and fine chemical raw materials. Herein, a novel polyoxometalate-based metal–organic framework (POMOF), [Co(bix)(H2O)]{V2O6} (VMOF-1, bix = 1,4-bis(imidazol-1-ylmethyl)benzene), is synthesized and structurally characterized. After removal of the coordinated water molecules of CoII ions by vacuum drying, VMOF-1a with both Lewis acid and Lewis base catalytic active-centers is achieved. VMOF-1a as the heterogeneous catalyst for the conversion of benzaldehyde and malononitrile to high value-added olefinic compounds under mild conditions, exhibits excellent conversion and selectivity, good recyclability and broad substrate applicability. Experimental and theoretical studies have revealed that CoII ion and {V2O6}2− unit in VMOF-1a synergistically catalyze the Knoevenagel condensation reaction: (1) {V2O6}2− is used as a Lewis base to pull out the proton of the active methylene group on malononitrile; (2) CoII ion acts as a Lewis acid to activate the carbonyl oxygen on benzaldehyde. Furthermore, it is demonstrated for the first time that the Lewis acid sites in POMOF can play the role of stabilize the alcohol hydroxyl anion intermediates generated during the reaction process, which further elucidates the reason for the high catalytic activity of VMOF-1a in the Knoevenagel condensation. This study provides theoretical guidance for the design of efficient and sustainable catalysts for Knoevenagel condensation.

3-/3,5-Styryl-Substituted BODIPY with N-Bridged Annulation: Synthesis and Spectroscopic Properties

AbstractThe development of organic dyes with high fluorescence quantum yield (FLQY) and tunable emission has significant application potential in biomedicine and material science. The synthesis of four N-bridged annulated BODIPY dyes with styryl units at the 3- and 3,5-positions of the BODIPY core, introduced by Knoevenagel condensation reaction, is reported. These dyes show high FLQY and tunable fluorescence. The intrinsic relationship between structure and properties is comprehensively analyzed through density functional theory (DFT) calculations, which is crucial for the rational design of new BODIPY dyes with desired properties for specific applications.

Synthesis, crystal structure investigation, and theoretical approaches to discover potential 6-bromo-3-cyanocoumarin as a potent inhibitor MetAP (methionine aminopeptidase) 2

It has been ascertained that trifluoroacetic acid accelerates the Knoevenagel condensation reaction of 5-bromosalicylaldehyde and ethyl ester of cyanoacetic acid. As a result, the 6-bromo-3-cyanocoumarin compound has been synthesized and the structure was eventually confirmed by X-ray analysis. Based on the structure-activity relationship and literature survey we found this compound has a potent inhibitor for MetAP (methionine aminopeptidase) and further we have studied molecular docking to understand the binding interactions and also performed ADME/T studies for this compound. The surface reactivity and intermolecular interactions of the studied compound were investigated by Hirshfeld surface analysis. Energy framework analysis shows the interaction between pair of fragments with neighbor molecules. Furthermore, the DFT study is performed to investigate structural reactivity and stability at B3LY/6-311+G(d,p) functional. The decreased HOMO-LUMO gap (3.97 eV) indicates its higher reactivity and soft nature. Molecular electrostatic potential (MESP) analysis and NBO charges indicate the structure's reactive site and charge transfer. Excited analysis by using the TD-DFT was performed to get excitation energy (ΔE), absorbance, and oscillator strength (fo) of crucial transition. Theoretically predicted values of polarizability (αo) and hyperpolarizability (βo) suggest their excellent optical and Nnar (NLO) properties.

A stable 3D Sr-MOF as an efficient heterogeneous catalyst for the cycloadditions of CO2 and knoevenagel condensation reactions

The catalytic activity of MOF is determined not only by its unique structure but also by the active sites from metal sites and functional ligands. A sTable 3D strontium complex, {[Sr2(BTCB)Cl(H2O)2]}n (Sr-BTCB), was synthesized under solvothermal condition. It is assembled with an amide-functionalized tricarboxylic acid and a Sr(II)-based infinite chain, where Sr2 repeating units are arranged sequentially. Two such 3D structures are interwoven to create a two-folded interpenetrated structure. The interpenetrated structure is strengthened by π-π interstacking between the central phenyl rings of ligands from different 3D structures. After solvent exchange and vacuum drying, the surface of nanochannels in desolvated Sr-BTCB is modified by unsaturated Sr2+ions. Complex Sr-BTCB has abundant Lewis acidic metal sites and Lewis basic sites of amide groups, as well as 1D rhombic channels. It exhibits excellent stability and heterogeneous catalysis on CO2 fixation reactions into cyclic carbonates and Knoevenagel condensation reactions of aldehydes and malononitrile.

An N-heterocyclic carbene functional covalent organic framework for Knoevenagel condensation reaction and γ-butyrolactone synthesis at room temperature

In this article, we have reported the conduction of an N-heterocyclic functional 2D COF, and the remarkable catalytic activity towards the Knoevenagel condensation reaction and the synthesis of γ-butyrolactones at room temperature.