Green Synthesis of Electrophilic Alkenes Using a Magnesium Catalyst under Aqueous Conditions and Mechanistic Insights by Density Functional Theory

A green approach for the synthesis of electrophilic alkenes has been developed via Knoevenagel condensation between active methylene compounds and carbonyl compounds using Mg powder under aqueous conditions. In this strategy, Mg(OH)2 acts as a catalyst, which was generated in situ by the reaction between metallic Mg (20 mol %) and water. Mg was found to be an efficient, nontoxic, and inexpensive metal catalyst system for producing a range of electrophilic alkenes in excellent yields (≤98%). A gram-scale synthesis of electrophilic alkenes has been developed, and Mg metal was recovered and recycled up to three times without an appreciable loss of catalytic activity. A catalytic cycle was proposed, and the reaction mechanism was investigated using density functional theory. The key steps are enolization of ethyl cyanoacetate, C-C bond formation, and then regeneration of the catalyst via metathesis with H2O. The overall reaction occurs easily with a maximum ΔG°⧧ value of 7.9 kcal/mol for the rate-determining C-C bond formation step. Our protocol has several advantages and can be further extended to one-pot sequential Knoevenagel condensation and Michael addition, and one-pot sequential Knoevenagel condensation and chemoselective reduction can be used for the synthesis of valuable precursors of pharmaceutical products under green and aqueous conditions.

COF-supported zirconium oxyhydroxide as a versatile heterogeneous catalyst for Knoevenagel condensation and nerve agent hydrolysis

A composite of catalytic Lewis acidic zirconium oxyhydroxides (8 wt %) and a covalent organic framework (COF) was synthesized. X-ray diffraction and infrared (IR) spectroscopy reveal that COF's structure is preserved after loading with zirconium oxyhydroxides. Electron microscopy confirms a homogeneous distribution of nano- to sub-micron-sized zirconium clusters in the COF. 3D X-ray tomography captures the micron-sized channels connecting the well-dispersed zirconium clusters on the COF. The crystalline ZrOx(OH)y@COF's nanostructure was model-optimized via simulated annealing methods. Using 0.8 mol % of the catalyst yielded a turnover number of 100-120 and a turnover frequency of 160-360 h-1 for Knoevenagel condensation in aqueous medium. Additionally, 2.2 mol % of catalyst catalyzes the hydrolysis of dimethyl nitrophenyl phosphate, a simulant of nerve agent Soman, with a conversion rate of 37% in 180 min. The hydrolytic detoxification of the live agent Soman is also achieved. Our study unveils COF-stabilized ZrOx(OH)y as a new class of zirconium-based Lewis + Bronsted-acid catalysts.

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.

Efficient synthesis of symmetrically substituted pyridines and substituted alkenes through green and heterogeneous catalysis with zinc phosphate

This study presents a new environmentally sustainable catalytic method for the synthesis of symmetrically substituted pyridine derivatives and substituted alkene derivatives using zinc phosphate (Zn3(PO4)2·4H2O) as a non-toxic and green heterogeneous catalyst. The catalytic support was prepared by a co-precipitation method, and it was applied for the first time as a heterogeneous catalyst in organic synthesis. Trisubstituted pyridine derivatives were prepared with excellent yields (82-94%) via a three-component, one-pot synthesis of aromatic aldehydes, substituted acetophenones, and ammonium acetate in the presence of 0.4 mol% of Zn3(PO4)2·4H2O using an ethanol/water (4/1) mixture as the solvent, while substituted alkenes were synthesized with up to 90% yield using the prepared catalyst. The experimental results demonstrate the efficiency of these new catalytic syntheses that present various advantages such as short reaction times, excellent yields, and an environmentally friendly profile.

Catalysis of a Diels-Alder Reaction between Azachalcones and Cyclopentadiene by a Recyclable Copper(II)-PEIP Metal-Organic Framework

Metal-organic frameworks (MOFs) have attracted considerable interest as emerging heterogeneous catalysts for organic transformations of synthetic utility. Herein, a Lewis-acidic MOF, {[Cu3(PEIP)2(5-NH2-mBDC)(DMF)]·7DMF}∞, denoted as Cu(ΙΙ)-PEIP, has been synthesized via a one-pot process and deployed as an efficient heterogeneous catalyst for a Diels-Alder cycloaddition. Specifically, the [4 + 2] cycloaddition of 13 substituted azachalcone dienophiles with cyclopentadiene has been investigated. MOF-catalyzed reaction conditions were optimized, leading to the selection of water as the solvent, in the presence of 10% mol sodium dodecyl sulfate (SDS) to address substrate solubility. The Cu(II)-PEIP catalyst showed excellent activity under these green and mild conditions, exhibiting comparable or, in some cases, superior efficiency to a homogeneous catalyst often employed in Diels-Alder reactions, namely, Cu(OTf)2. The nature of the azachalcone substituent played a significant role in the reactivity of the dienophiles, with electron-withdrawing (EW) substituents enhancing conversion and electron-donating (ED) ones exhibiting the opposite effect. Coordinating substituents appeared to enhance the endo selectivity. Importantly, the Cu(II)-PEIP catalyst can be readily isolated from the reaction mixture and recycled up to four times without any significant reduction in conversion or selectivity.

Two pillared-layer metal-organic frameworks based on the pinwheel trinuclear carboxylate-clusters of Zn(II) and Co(II): synthesis, crystal structures, magnetic study, and Lewis acid catalysis

Using a dicarboxylic acid, [1,1'-biphenyl]-4,4'-dicarboxylic acid (H₂L1) and an exobidentate ligand, (1E,1'E)-N,N'-(1,4-phenylene)bis(1-(pyridin-4-yl)methanimine) (L2), two 3D interpenetrated networks, {[Zn₃(L1)₃(L2)]·9H₂O}_n (Zn-MOF) and {[Co₃(L1)₃(L2)(DMF)]·0.5DMF}_n (Co-MOF), have been prepared in good yields. The crystal structure analysis of Zn-MOF and Co-MOF revealed that both have a 3D pillared-layer structure based on pinwheel trinuclear metal-carboxylate clusters as secondary building units (SBUs). Furthermore, the structures also exhibited three-fold interpenetration. Although the overall networks in Zn-MOF and Co-MOF showed significant resemblances, there are marked differences in their crystal structures, which are associated with the coordination environment of the metal centre and the binding modes of the carboxylates. Gas adsorption studies (N₂ at 77 K and 1 bar) indicated that Co-MOF is more porous than Zn-MOF. Magnetic measurements on Co-MOF indicate a significant antiferromagnetic interaction (45 K to 303 K) between trimeric Co(II) S = 3/2 spins through syn-syn carboxylato bridges. Both MOFs were studied for the Lewis acid catalyzed Knoevenagel condensation reactions between benzaldehydes and malononitrile with an active methylene group, where Zn-MOF was found to be a better catalyst than Co-MOF. This was supported by the Monte Carlo simulations indicating the better substrate binding ability of Zn-MOF than Co-MOF.

Ultrasensitive Determination of Natural Flavonoid Rutin Using an Electrochemical Sensor Based on Metal-Organic Framework CAU-1/Acidified Carbon Nanotubes Composites

Rutin, a natural flavonol glycoside, is widely present in plants and foods, such as black tea and wheat tea. The antioxidant and anti-inflammatory effects of flavonoids are well known. In this study, a new electrochemical rutin sensor was developed using multiwalled carbon nanotubes/aluminum-based metal-organic frameworks (MWCNT/CAU-1) (CAU-1, a type of Al-MOF) as the electrode modification material. The suspension of multiwalled carbon tubes was dropped on the surface of the GCE electrode to make MWCNT/GCEs, and CAU-1 was then attached to the electrode surface by electrodeposition. MWCNTs and CAU-1 were characterized using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Due to the synergistic effect of CAU-1 and MWCNT-COOH, the prepared sensor showed an ultrasensitive electrochemical response to rutin. Under optimized conditions, the sensor showed a linear relationship between 1.0 × 10^-9~3.0 × 10^-6 M with a detection limit of 6.7 × 10^-10 M (S/N = 3). The sensor also showed satisfactory stability and accuracy in the detection of real samples.

Growth Pattern Control and Nanoarchitecture Engineering of Metal-Organic Framework Single Crystals by Confined Space Synthesis

The nanoarchitecture engineering of metal-organic frameworks (MOFs) is a fascinating but intellectually challenging concept that opens up avenues for both tailoring the properties of MOFs and expanding their applications. Herein, we report the confined growth of ZIF-8 single crystals in a three-dimensionally ordered (3DO) macroporous polystyrene replica and reveal that their growth patterns, morphologies, and nanoarchitectures can be highly engineered using the concentration of the precursor. Impressively, the favorable in situ confined growth enables the successful fabrication of 3DO sphere-assembled ZIF-8 single crystals or 3DO single-crystalline ZIF-8 sphere arrays when a low- or high-concentration precursor solution, respectively, is used as the feedstock. Furthermore, our strategy can be extended to the preparation of other 3DO MOF single crystals, including ZIF-67 and HKUST-1, with similar controllable hierarchical nanoarchitectures. With the successful preparation of a series of diameter-tunable ZIF-8 single-crystalline spheres, we further unravel their interesting size-performance relationship in the Knoevenagle reaction between benzaldehyde and malononitrile, wherein the smallest spheres show the fastest first-order reaction kinetics. This study not only develops a general strategy for engineering the nanoarchitectures of MOF single crystals but also provides fundamental knowledge of the mechanism for the growth of hierarchical single crystals under confined spaces.

Diamino group-functionalized Zr-based metal-organic framework for fluorescence sensing of free chlorine in the aqueous phase and Knoevenagel condensation

We developed a porous diamino group-functionalized Zr(IV) metal-organic framework (MOF). The synthesized MOF has a similar structure to DUT-52 (DUT = Dresden University of Technology), which has a face-centered cubic structure with an Fm3̄m space group. The synthesized material (DUT-52-(NH2)2-1) was solvent exchanged with methanol (MeOH) and activated at 100 °C overnight. Both the as-synthesized and activated materials (DUT-52-(NH2)2-1') are thermally stable until 300 °C. The Brunauer-Emmett-Teller (BET) surface area of DUT-52-(NH2)2-1' was found to be 413 m² g^-1. DUT-52-(NH2)2-1' showed a significant quenching of fluorescence response after coming in contact with free chlorine (ClO^-) in an aqueous medium. The selectivity of DUT-52-(NH2)2-1' towards ClO^- was not significantly hampered in the presence of any competitive ion. The limit of detection (LOD) value was found to be 0.08 μM in phosphate-buffered saline (PBS, pH = 7.4). DUT-52-(NH2)2-1' is recyclable and very sensitive towards ClO^-. Moreover, the paper strip method was developed for onsite identification of ClO^-. Furthermore, the catalytic activity of DUT-52-(NH2)2-1' was tested in the Knoevenagel condensation between benzaldehyde and cyanoacetamide. The experimental results clearly indicate that DUT-52-(NH2)2-1' exhibits high activity with very high selectivity towards condensation products. The solid was reusable three times with no decay in its activity, as evidenced by powder X-ray diffraction (PXRD), field emission scanning electron microscopy (FE-SEM) and fourier transform infrared (FT-IR).

Contribution of Knoevenagel Condensation Products towards Development of Anticancer Agents: An Updated Review

Knoevenagel condensation is an entrenched, prevailing, prominent arsenal following greener principles in the generation of α, β-unsaturated ketones/carboxylic acids by involving carbonyl functionalities and active methylenes. This reaction has proved to be a major driving force in many multicomponent reactions indicating the prolific utility towards the development of biologically fascinating molecules. This eminent reaction was acclimatised on different pharmacophoric aldehydes (benzimidazole, β-carboline, phenanthrene, indole, imidazothiadiazole, pyrazole etc.) and active methylenes (oxindole, barbituric acid, Meldrum's acid, thiazolidinedione etc.) to generate the library of chemical compounds. Their potential was also explicit to understand the significance of functionalities involved, which thereby evoke further developments in drug discovery. Furthermore, most of these reaction products exhibited remarkable anticancer activity in nanomolar to micromolar ranges by targeting different cancer targets like DNA, microtubules, Topo-I/II, and kinases (PIM, PARP, NMP, p300/CBP) etc. This review underscores the efficiency of the Knoevenagel condensation explored in the past six-year to generate molecules of pharmacological interest, predominantly towards cancer. The present review also provides the aspects of structure-activity relationships, mode of action and docking study with possible interaction with the target protein.

MOF-enabled confinement and related effects for chemical catalyst presentation and utilization

A defining characteristic of nearly all catalytically functional MOFs is uniform, molecular-scale porosity. MOF pores, linkers and nodes that define them, help regulate reactant and product transport, catalyst siting, catalyst accessibility, catalyst stability, catalyst activity, co-catalyst proximity, composition of the chemical environment at and beyond the catalytic active site, chemical intermediate and transition-state conformations, thermodynamic affinity of molecular guests for MOF interior sites, framework charge and density of charge-compensating ions, pore hydrophobicity/hydrophilicity, pore and channel rigidity vs. flexibility, and other features and properties. Collectively and individually, these properties help define overall catalyst functional behaviour. This review focuses on how porous, catalyst-containing MOFs capitalize on molecular-scale confinement, containment, isolation, environment modulation, energy delivery, and mobility to accomplish desired chemical transformations with potentially superior selectivity or other efficacy, especially in comparison to catalysts in homogeneous solution environments.

Donor–acceptor strategy to construct near infrared AIEgens for cell imaging

A donor–acceptor strategy was applied to construct NIR AIEgens. Six new AIEgens were obtained and among them, DMNIC exhibited the longest emission maximum at 694 nm and was successfully applied for NIR cell imaging.

Nanochannel-Based {BaZn}-Organic Framework for Catalytic Activity on Cycloaddition Reaction of Epoxides with CO2 and Deacetalization-Knoevenagel Condensation

Because of the integrated properties from chemically dissimilar metals, microporous heterometallic MOFs have wider potential applicability, which prompts us to explore the tendency collocation of different metal cations in the...

Taguchi-Assisted Optimization Technique and Density Functional Theory for Green Synthesis of a Novel Cu-MOF Derived From Caffeic Acid and Its Anticancerious Activities

In this paper, we have reported an innovative greener method for developing copper-metal organic frameworks (Cu-MOFs) using caffeic acid (CA) as a linker extracted from Satureja hortensis using ultrasonic bath. The density functional theory is used to discuss the Cu-MOF-binding reaction mechanism. In order to achieve a discrepancy between the energy levels of the interactive precursor orbitals, the molecules have been optimized using the B3LYP/6-31G method. The Taguchi method was used to optimize the key parameters for the synthesis of Cu-MOF. FT-IR, XRD, nitrogen adsorption, and SEM analyses are used to characterize it. The adsorption/desorption and SEM analyses suggested that Cu-MOF has a larger surface area of 284.94 m2/g with high porosity. Cu-MOF has shown anticancer activities against the human breast cancer (MDA-MB-468) cell lines, and it could be a potent candidate for clinical applications.

Nanochannel {InZn}-Organic Framework with a High Catalytic Performance on CO2 Chemical Fixation and Deacetalization-Knoevenagel Condensation

The rare combination of In^III 5p and Zn^II 3d in the presence of a structure-oriented TDP^6- ligand led to a robust hybrid material of {(Me₂NH₂)[InZn(TDP)(OH₂)]·4DMF·4H₂O}_n (NUC-42) with the interlaced hierarchical nanochannels (hexagonal and cylindrical) shaped by six rows of undocumented [InZn(CO₂)₆(OH₂)] clusters, which represented the first 5p-3d nanochannel-based heterometallic metal-organic framework. With respect to the multifarious symbiotic Lewis acid-base and Brønsted acid sites in the high porous framework, the catalytic performance of activated NUC-42a upon CO₂ cycloaddition with styrene oxide was evaluated under solvent-free conditions with 1 atm of CO₂ pressure, which exhibited that the reaction could be well completed at ambient temperature within 48 h or at 60 °C within 4 h with high yield and selectivity. Moreover, because of the acidic function of metal sites and a central free pyridine in the TDP^6- ligand, deacetalization-Knoevenagel condensation of acetals and malononitrile could be efficiently facilitated by an activated sample of NUC-42a under lukewarm conditions.

The impact of framework flexibility and defects on the water adsorption in CAU-10-H

Aluminum-based metal-organic framework (MOF) CAU-10-H is a promising candidate for heat transformation and water harvesting applications due to its hydrothermal stability, beneficial step-wise water adsorption isotherm and low toxicity. In this study, the effects of the framework flexibility and structural defects on the mechanism of water sorption in CAU-10-H were studied by grand canonical Monte Carlo (GCMC) methods. It was shown by the simulations that the rigid ideal MOF framework is hydrophobic. The account of the linker "flapping" motion during the simulations made the framework more hydrophilic due to unblocking of hydroxyl groups that are inaccessible to water molecules for the rigid structure model. However, this model cannot predict the experimental pressure, at which the step on the adsorption isotherm is observed. Based on this result, we suggested that the presence of structural defects could increase the MOF hydrophilicity. The investigation of the water adsorption using several models of defective structures demonstrated that even a small number of defects shift the calculated position of the step on the adsorption isotherm towards the experimental values. The results obtained in this study emphasize that the controlled synthesis of defective structures is one of the most efficient methods of regulating the MOF adsorption properties.

Ag2CO3 containing magnetic nanocomposite as a powerful and recoverable catalyst for Knoevenagel condensation

In this paper, the synthesis, characterization and catalytic application of a novel magnetic silica-supported Ag2CO3 (MS/Ag2CO3) with core-shell structure are developed. The MS/Ag2CO3 nanocomposite was prepared through chemical modification of magnetic MS nanoparticles with AgNO3 under alkaline conditions. The structure, chemical composition and magnetic properties of MS/Ag2CO3 were investigated by using VSM, PXRD, FT-IR, EDX and SEM techniques. The MS/Ag2CO3 nanocomposite was used as an effective catalyst for the Knoevenagel condensation under solvent-free conditions at 60 °C in an ultrasonic bath. The recovery and leaching tests were performed to study the nature of the MS/Ag2CO3 catalyst under applied conditions.

Catalytic C-H Bond Activation and Knoevenagel Condensation Using Pyridine-2,3-Dicarboxylate-Based Metal-Organic Frameworks

Three 1D coordination polymers (CPs) [M(pdca)(H2O)2] n (M = Zn, Cd, and Co; 1-3), and a 3D coordination framework {[(CH3)2NH2][CuK(2,3-pdca)(pa)(NO3)2]} n (4) (2,3-pdca = pyridine-2,3-dicarboxylate and pa = picolinic acid), have been synthesized adopting a solvothermal reaction strategy. The CPs have been thoroughly characterized using various spectral techniques, that is, elemental analyses, FT-IR, TGA, DSC, UV/vis, and luminescence. Structural information on 1-4 was obtained by PXRD and X-ray single-crystal analyses, whereas morphological insights were attained through FESEM, AFM, EDX, HRTEM, and BET surface area analyses. Roughness parameters were calculated from AFM analysis, whereas dimensions of small domains and interplanar spacing were defined with the aid of HRTEM. CPs 1-3 are 1D isostructural networks, whereas 4 is a 3D framework. Moreover, 1-4 display moderate luminescence at rt. In addition, 1-4 have been applied as economic and efficient porous catalysts for the Knoevenagel condensation reaction and C-H bond activation under mild conditions with good yields (95-98 and 97-99%), respectively. Notably, 1-3 can be reused up to seven cycles, whereas 4 can be reused up to five catalytic cycles with retained catalytic efficiency. Relative catalytic efficacy toward the Knoevenagel condensation reaction follows in the order 2 > 1 > 3 > 4, whereas 2 > 4 > 1 > 3 for C-H activation. The present result demonstrates synthetic, structural, optical, morphological, and catalytic aspects of 1-4.

Three Resorcin[4]arene-Based Two-Dimensional Zn(II) Supramolecular Isomers Synthesized via a Structure-Directing Strategy for Knoevenagel Condensation

Herein, in the presence of three structure-directing agents (SDAs), a family of imidazole-functionalized resorcin[4]arene-based coordination polymers (CPs), [Zn(TIC4R)(HCOO)]·HCOO·0.5DMF·1.5H₂O (1), [Zn(TIC4R)(CN)]·HCOO·DMF·2.5H₂O (2), and [Zn(TIC4R)(H₂O)]·2HCOO·2H₂O (3), were assembled under solvothermal conditions [TIC4R = tetra(imidazole) resorcin[4]arene]. 1 exhibits a double-layer structure with rectangle windows, and 2 and 3 display monolayer structures. The layers of CPs 2 and 3 are slides with different offsets along the a-axis. In addition, three CPs were used as catalysts to catalyze Knoevenagel condensations. Strikingly, all CPs exhibit remarkable catalytic performance for several substrates. To the best of our knowledge, this is the first time that a small organic acid as SDA was used in the syntheses of resorcin[4]arene-based supramolecular isomers.

HKUST-1 Metal Organic Framework as an Efficient Dual-Function Catalyst: Aziridination and One-Pot Ring-Opening Transformation for Formation of β-Aryl Sulfonamides with C-C, C-N, C-S, and C-O Bonds

Metal-organic frameworks (MOFs) are extensively used in catalysis due to their robust structure, well-defined periodic reaction centers, and high porosity. We report Cu₃(BTC)₂·(H₂O)₃ (HKUST-1) as an efficient heterogeneous catalyst for aziridination of alkene and ring-opening reaction of activated aziridines. Furthermore, we demonstrate that the transfer of a nitrogen group from PhINTs to olefins and its analogue to give aziridines takes place at the coordinatively unsaturated Cu(II) site of Cu₃(BTC)₂-MOF; however, the ring opening of activated aziridines is controlled by the Cu(II) Lewis acid site, and generation of coordinative unsaturation by thermal activation of the MOF is not necessarily important. The key advantage of this catalytic approach is the direct formation of C-C, C-N, C-O, and C-S bonds yielding β-aryl sulfonamide derivatives through a simultaneous aziridination ring-opening reaction of the alkene in one pot using a single catalyst.

Ion-Exchange Fabrication of Hierarchical Al-MOF-Based Resin Catalysts for the Tandem Reaction

Metal-organic framework (MOF)-supported macroscale resin catalysts, IRA900(xOH)-MIL-101(Al)-NH₂ (x means the concentration of NaOH), with spatially isolated antagonistic acid-base active sites were successfully synthesized through a novel strategy by ion exchange and in situ solvothermal methods. The hierarchical pore system of the as-prepared catalysts effectively promotes the mass transfer and contacts with catalytic active centers during the organic reactions. Therefore, the environmentally friendly catalysts exhibit excellent superior activity and stability in one-pot deacetalization-Knoevenagel condensation reaction, and the yield by optimal IRA900(0.2OH)-MIL-101(Al)-NH₂ reaches close to 99% after 5 h at 110 °C. Thanks to the millimeter-sized resin carrier and robust sphere morphology, the recycling of the as-prepared catalysts only requires natural sedimentation. This work presents an effective strategy to build low-toxic acid-base catalysts by combining the advantages of ion-exchange resins and functionalized MOF materials.

Metal Organic Framework - Based Mixed Matrix Membranes for Carbon Dioxide Separation: Recent Advances and Future Directions

Gas separation and purification using polymeric membranes is a promising technology that constitutes an energy-efficient and eco-friendly process for large scale integration. However, pristine polymeric membranes typically suffer from the trade-off between permeability and selectivity represented by the Robeson's upper bound. Mixed matrix membranes (MMMs) synthesized by the addition of porous nano-fillers into polymer matrices, can enable a simultaneous increase in selectivity and permeability. Among the various porous fillers, metal-organic frameworks (MOFs) are recognized in recent days as a promising filler material for the fabrication of MMMs. In this article, we review representative examples of MMMs prepared by dispersion of MOFs into polymer matrices or by deposition on the surface of polymeric membranes. Addition of MOFs into other continuous phases, such as ionic liquids, are also included. CO2 separation from hydrocarbons, H2, N2, and the like is emphasized. Hybrid fillers based on composites of MOFs with other nanomaterials, e.g., of MOF/GO, MOF/CNTs, and functionalized MOFs, are also presented and discussed. Synergetic effects and the result of interactions between filler/matrix and filler/filler are reviewed, and the impact of filler and matrix types and compositions, filler loading, surface area, porosity, pore sizes, and surface functionalities on tuning permeability are discoursed. Finally, selectivity, thermal, chemical, and mechanical stability of the resulting MMMs are analyzed. The review concludes with a perspective of up-scaling of such systems for CO2 separation, including an overview of the most promising MMM systems.

Size and function influence study on enhanced catalytic performance of a cooperative MOF for mild, green and fast C-C bond formation

Tuning of pore function and size (surface area) are two key factors that play important roles in the performance of metal-organic-frameworks (MOFs) as catalysts. The catalytic performance of two bulk and nanosized MOFs with different functional groups such as a Brønsted base and Lewis acid was studied in line with the sustainable development of catalysts and green chemistry principles. Bifunctional imine decorated TMU-33, ([Cd3(BDC)3(OPP)(DMF)2]·2DMA)n (TMU-33), (OPP: N,N'-(oxybis(4,1-phenylene))bis(1-(pyridin-4yl)methanimine)), with an adjustable structure and amine functionalized TMU-40, [Zn(BDC)(L*)]·DMF, (L*: N1,N2-bis(pyridin-4-ylmethylene)ethane-1,2-diamine), were evaluated in the C-C bond forming reaction under mild and green conditions. The results show that the nanosized samples of bifunctional TMU-33 which simultaneously have an imine and open metal site exhibit higher performance as Knoevenagel catalysts. Furthermore, among the nanosized samples, the nanoplate TMU-33 with more access to open metal sites shows the highest catalytic activity without any side product in water, at room temperature for 5 min, which confirms that the Lewis acid is the effective catalyst for this reaction. The catalyst could be reused for at least three cycles without any significant loss of its activity. The performance of the structure indicates that the tuning of functionality of MOFs can be a very promising route for the extension of green catalysts.

Z-Acrylonitrile Derivatives: Improved Synthesis, X-ray Structure, and Interaction with Human Serum Albumin

AIMS AND OBJECTIVE

In the synthesis of heterocyclic compounds, acrylonitrile derivatives are the most important and appropriate precursors. These compounds are the most important intermediates and subunits for the enhancement of molecules having pharmaceutical or biological interests. Nitrogen-containing compounds have received extensive consideration in the literature over the years.

MATERIALS AND METHODS

A facile, economic and efficient method has been developed for the synthesis of acrylonitrile derivatives using p-nitrophenylacetonitrile and aromatic/heterocyclic aldehydes in the presence of zinc chloride at room temperature. Spectroscopic data were obtained using the following instruments: Fourier transform infrared spectra (KBr discs, 4000-400 cm-1) by Shimadzu IR-408 Perkin-Elmer 1800 instrument; 1H NMR and 13C NMR spectra by Bruker Avance-II 400 MHz using DMSO-d6 as a solvent containing TMS as the internal standard.

RESULTS

To continue our ongoing studies to synthesize heterocyclic and pharmaceutical compounds by mild, facile and efficient protocols, herein we wish to report our experimental results on the synthesis of acrylonitrile derivatives, using various aromatic/heterocyclic aldehydes and p-nitrophenylacetonitrile in the presence of zinc chloride in ethanolic media at room temperature. Some of the new compounds were tested for their human serum albumin activity (HSA) while a study of interaction with HSA protein was performed for compounds 3a and 3b. The results show that compound 3b binds tightly to HSA as compared to compound 3a.

CONCLUSION

It can be concluded that acrylonitrile derivatives can be synthesized by an efficient method via the reaction of p-nitrophenylacetonitrile with aromatic/heterocyclic aldehydes by the use of zinc chloride as an effective solid catalyst. The remarkable features of this procedure include excellent yields (90-95%), short reaction period (30 min.), moderate reaction environment, easy workup procedure and managing of the catalyst. This method may find a wide significance in organic synthesis for the synthesis of the Z-acrylonitrile.

Templated nanoreactor arrays for nanoscale-tunable liquid-phase catalysis

We demonstrate templated synthesis of arrayed metal oxide-based nanoreactors as candidate platforms for liquid-phase catalysis. A case study of zinc oxide nanotubes revealed high-level catalytic reactivity and nanoscale-tunable kinetics, either for Knoevenagel condensation or radical-mediated oxidation, owing to the ordered nanostructures and optimized surface.

Metal-Assembled, Resorcin[4]arene-Based Molecular Trimer for Efficient Removal of Toxic Dichromate Pollutants and Knoevenagel Condensation Reaction

Self-assembly of resorcin[4]arene-based coordination cages involving more than two resorcin[4]arenes poses significant challenges for the requirements of suitable functionalized resorcin[4]arene ligands and metals. Here, we report an unusual example of a metal-coordinated, resorcin[4]arene-based molecular trimer (1-NO₃), composed of three resorcin[4]arenes and three Cd(II) cations. In particular, 1-NO₃ features efficient and selective removal of environmentally toxic dichromate (Cr₂O₇^2-) anions. Moreover, the Knoevenagel condensation reaction was also explored by using 1-NO₃ as an efficient heterogeneous catalyst.