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Chemosensor (CS1) was designed and synthesized by simple green chemistry procedure. CS1 exhibited both colorimetric and fluorescence turn-off responses for cyanide (CN-) ion in aqueous solution. The probe showed an immediate visible color chang

Two compounds, 2–(4–hydroxybenzylidene)malononitrile (1a) and 2–[4–(dimethylamino)benzylidene]malononitrile (2), were synthesized with a view to their use as optical devices for anionic detection. Compound 1a was studied as a chromogenic chemosensor using an acid–base strategy. In purely aqueous medium, 1a was used in the detection of CN? with high selectivity. This is possible because the colorless solution of the compound becomes yellow upon addition of the anion, which acts as a base and abstracts the hydrogen from the phenolic moiety of the molecule, generating the corresponding dye (1b). Optical detection and optical quantification limits were determined as 6.17?×?10??7?mol?L??1 and 2.06?×?10??6?mol?L??1, respectively. These values are much lower than the maximum level of the concentration of CN? allowed by the World Health Organization in potable water (1.7?μmol?L??1). Compound 2 was used in a chemodosimeter approach for the highly selective detection of CN? in water with cetyltrimethylammonium bromide above its critical micellar concentration. Solutions of 2 are yellow but become colorless with the addition of the anion. This is because CN? attacks the CH[dbnd]C double bond in the compound and disrupts the electronic conjugation between the electron donating and the electron accepting moieties of the dye. Thus, with the addition of CN? to the medium compound 1a acts as an off–on optical device while dye 2 operates as an on–off chemodosimeter.

A new ligand with D-π-A symmetry has been synthesized in high yield by Knoevenagel condensation of 4-(dimethylamino)benzaldehyde with malononitrile. The ligand forms coordination polymers with Ag(I) salts at room temperature where the ultimate structure i

A new, efficient and green methodology has been developed for the Knoevenagel condensation using catalytic amount of mesoporous titanosilicate catalyst Ti-TUD-1, under mild conditions at room temperature. The method generates trisubstituted electrophilic olefins in high yields within short reaction time. The mesoporous nature of the catalyst having high surface area helps in binding the substrate to the active site. The advantage of this catalyst is its reusability with almost consistent reactivity thereby making it viable for industrial applications.

A new and an efficient synthesis of 4-imino-3-(arylidene)-azetidine-2-thiones is reported. The reaction of arylidenemalononitriles with phosphorus pentasulfide and ethanol affords the title products in good yields. Elemental analysis, infrared, 1/su

A new and efficient green grinding-based catalyst free Knoevenagel condensation of aldehydes/ketones and malononitrile for the rapid preparation of twelve malononitrile derivatives (C1-C12) is proposed. Characterization of the derivatives was done by sup

A novel, heterogeneous and homogeneous basic nanocatalysts were synthesized by grafting of lithium and cesium on zagrosian natural asphalt sulfonate (Li/Cs-Zagronas). The activity of these catalysts was examined in the Claisen–Schmidt and Knoevenagel condensations under mild reaction conditions. Li/Cs-Zagronas were characterized by FT-IR spectroscopy, scanning electron microscopy, X-ray diffraction, energy-dispersive spectroscopy, inductively coupled plasma and thermogravimetric analysis techniques. These nanocatalysts were removed by simple filtration and reused several times without any deterioration of activity.

RTILs exhibit supramolecular self-assembled polymeric aggregation due to noncovalent interactions. The influence of the aggregation behaviour of RTILs on catalytic activity is evident but still poorly understood. The present work focuses on establishing a

Four new mononuclear/coordination polymeric (CP) zinc(II) complexes (1-4) of ferrocenyl/pyridyl-functionalized dithiocarbamate ligands, N-ferrocenylmethyl-N-butyl dithiocarbamate (L1), N-ferrocenylmethyl-N-ethylmorpholine dithiocarbamate (L2), N-ferroceny

In this work, [H2-Bisim][H2PO4]2 as a novel bis-imidazole-based acidic ionic liquid has been synthesized and characterized with a variety of techniques including FT-IR, 1H, 13C, 31/su

Aim and Objective: In this work, we tried to introduce a non-toxic and stable organic compound named succinimide as a green and efficient organo-catalyst for the promotion of the synthesis of arylidene malononitrile and tetrahydrobenzo[b]pyran derivatives

In this paper, the synthesis of magnetic cored amino group terminated dendrimer (Fe3O4@SiO2@PAMAM-G2) through covalent bonding was described. This catalyst was characterized by FT-IR, XRD, FE-SEM, TEM, and TGA d

Ionic Liquids (ILs) self-assemble to form supramolecular polymeric clusters/aggregates. The aggregation behavior of ILs influences its activity in the organic synthesis. However, the precise role of ILs in organic reactions is still unknown. It is, therefore, important to comprehend the supramolecular polymeric aggregation behavior of ILs. We are exploring the supramolecular polymeric aggregation behavior of ILs using Electrospray Ionization Mass Spectrometry (ESI-MS). We have synthesized four hydrophilic ILs (1–4) and investigated their aggregation behavior and its impact on catalytic activity in Carbon-Carbon bond formation (Knoevenagel and Claisen-Schmidt condensation). Here, we show that the aggregation behavior of ILs depends on the type and nature of cation and anion. ESI-MS (?ve) spectra reveals two different type of aggregation i.e. [CnAn+1]? & [A2 + H+]?. We have found that catalytic activity increases with increased [CnAn+1]? supramolecular aggregation. Consequently, highest yield of products obtained in ILs which show decreased anion-anion aggregation [A2 + H+]? abundance in ESI-MS. We anticipate our results to be a starting point for the establishment of desired ILs for organic synthesis.

Organo-catalysts have been under great consideration for many years because of their performance and selectivity in the reactions. In this work, a new bis-succinimide (Bis-Su) compound is prepared, identified and used as a green and efficient basic organo

While organic donor-acceptor (D-A) molecules are widely employed in multiple areas, the application of more D-A molecules could be limited because of an inherent polarity sensitivity that inhibits photochemical processes. Presented here is a facile chemical modification to attenuate solvent-dependent mechanisms of excited-state quenching through addition of a β-carbonyl-based polar substituent. The results reveal a mechanism wherein the β-carbonyl substituent creates a structural buffer between the donor and the surrounding solvent. Through computational and experimental analyses, it is demonstrated that the β-carbonyl simultaneously attenuates two distinct solvent-dependent quenching mechanisms. Using the β-carbonyl substituent, improvements in the photophysical properties of commonly used D-A fluorophores and their enhanced performance in biological imaging are shown.

The P2X7 receptor (P2X7R) is an ion channel which is activated by interactions with the extracellular ATP molecules. The molecular complex P2X7R/ATP induces conformational changes in the protein subunits, opening a pore in the ion channel macromolecular s

In the present work, 3,3′-(butane-1,4-diyl)bis(1-methyl-1H-imidazol-3-ium) dichloride ([C4(MIm)2]·2Cl) and 3,3′-(butane-1,4-diyl)bis(1-methyl-1H-imidazol-3-ium) hydrogen sulfate ([C4(MIm)2]·2HSO4) were prepared via adequate, solvent-free methods and characterized using FT-IR, 1H NMR, 13C NMR, and potentiometric titration techniques. These reagents were investigated in the synthesis of 5-arylidene (thio)barbituric acids, 2-arylidene malononitriles, 4H-pyrans, and pyrano[2,3-d] pyrimidineones, and their catalytic activities were compared in the promotion of these reactions. Based on the obtained results, we found that [C4(MIm)2]·2Cl showed more catalytic efficiency where a basic or weak acidic media is needed. In contrast, [C4(MIm)2]·2HSO4 is a powerful catalyst in reactions needing acidic catalysts to enhance the reaction rate. Using these reagents, the products were formed under mild and eco-friendly conditions in excellent yields during short reaction times without needing column chromatography for work-up.

Abstract: In the present work, we explored novel CeZrO4?δ as a catalyst for Knoevenagel condensation of aldehydes with reactive methylene compounds like malononitrile and ethylcyanoacetate. For the present study, ceria, zirconia and CeZrO4

An efficient and ultrasound-assisted route to the synthesis of arylidene malononitriles/methylciano- or ethylciano acetates in a one-pot reaction catalyzed by silica sodium carbonate nanoparticles (SSC NPs) is described. In this reaction, SSC NPs demonstrated high efficiency as catalyst to obtain target products. By this achievement, a wide range of α,β-unsaturated compounds as Knoevenagel condensation products with good to excellent yields are obtained from reaction between numerous arylaldehydes, and malononitrile, methyl cianoacetate or ethyl cianoacetate. Target products which prepared in high yield and high purity can be candidate as important biologically active molecules. This method is an easy, cheap, rapid and highly efficient for the synthesis of desired products. In addition, capability of catalyst to separate from reaction mixture and reuse in further runs and being compatible with green chemistry are considered as other advantages of this procedure. All products were deduced from their FT-IR and FT-NMR spectroscopic and elemental analysis data.

This paper presents a new green protocol for Knoevenagel condensations of aldehydes and compounds with an active methylene group in a binary mixture of ethanol/water (3:7, v/v). This medium favored the uncatalyzed Knoevenagel reactions and easy workup pro

Molecules containing an (cyanovinyl)arene moiety are known as tyrphostins because of their ability to inhibit proteins from the tyrosine kinase family, an interesting target for the development of anticancer and trypanocidal drugs. In the present work, (E

In this paper, guanidine groups (Gn) supported on modified magnetic nanoparticles (Fe3O4–4,4′-MDI) were synthesized for the first time. The catalyst synthesized was characterized by various techniques such as SEM (Scanning Electron M

A series of novel N-methyl piperidine (Nmp)-based ionic liquids with 1,2-propanediol group are synthesized and used as catalysts for both hetero-Michael addition of α,β-unsaturated amides and Knoevenagel condensation at room temperature in water; and all the examined substrates could be transformed into corresponding products in good to excellent yields. Meanwhile IL-catalyzed hetero-Michael addition of α,β-unsaturated amides in water has not been reported in the previous literatures. Additionally, the catalyst is recyclable for the two reactions. This finding provides a green catalyst for both hetero-Michael addition of α,β-unsaturated amides and Knoevenagel condensation in water.

Sulfamic acid immobilized on diethylenetriamine functionalized Fe3O4 nanoparticles (SA-DETA-Fe3O4) was successfully prepared and characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM), thermo gravimetric analysis (TGA), X-Ray diffraction (XRD) and scanning electron microscopy (SEM). The sulfamic acid was found as a magnetically separable and highly active catalyst for the oxidative coupling thiols, oxidation of sulfides. Furthermore, the SA-DETA-Fe3O4 showed the high catalytic activity in Knoevenagel condensation of aromatic aldehydes with active methylene compounds (malononitrile and ethyl cynoacetate). The nanosolid catalyst could be easily recovered by a simple magnetic separation and reused for many cycles without deterioration in catalytic activity.

Abstract: The complex catalyst of [ZnClO.urea]?[Ch.urea]+ has been prepared by dissolving of nanoZnO in choline chloride:2urea at 50 °C. The concentration of [ZnClO.urea]? in the given liquid is 19,987 ppm and 10.5 times h

A series of novel N-methyl morpholine (Nmm) based ionic liquids with 1,2-propanediol group were synthesized and used as catalysts for Knoevenagel condensation at room temperature in water. Under the effect of the catalyst, various aldehydes or aliphatic ketones could react with a wide range of activated methylene compounds well, including malononitrile, alkyl cyanoacetate, cyanoacetamide, β-diketone, barbituric acid, 2-arylacetonitrile and thiazolidinedione. Furthermore, most of the products could be separated just by filtrating and washing with water. Additionally, the catalyst is recyclable and applicable for the large-scale synthesis.

Fe3O4 magnetic nanoparticles (MNPs) were obtained using a reduction–precipitation method. These MNPs were modified with cysteamine hydrochloride. This catalyst was characterized using a number of physicochemical measurements. The Fe

Tribenzylammonium tribromide supported onto magnetic nanoparticles (Br3-TBA-Fe3O4) as a bromine source was successfully synthesized and characterized using Fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy and vibrating sample magnetometry. The synthesized catalyst is shown to be a versatile and highly efficient heterogeneous catalyst for the Knoevenagel condensation and synthesis of 2,3-dihydroquinazolin-4(1H)-one and polyhydroquinoline derivatives. To the best of the authors' knowledge, this is the first report of the use of a bromine source immobilized on Fe3O4 nanoparticles as a magnetically separable catalyst for these reactions. The nanosolid catalyst can be magnetically recovered and reused readily several times without significant loss in catalytic efficiency.

Abstract: Diethylenetriamine immobilized on magnetic Fe3O4 nanoparticles (DETA-Fe3O4) was successfully prepared as a new and well dispersed magnetically separable amine catalyst. The structure of the resulting catalyst was well characterized by a series of analysis techniques such as FT-IR, SEM, EDX, VSM, TGA and XRD. The catalytic activity of DETA-Fe3O4 was evaluated with Knoevenagel condensation of active methylene compounds with aromatic aldehydes. Interestingly, the cyclocondensation of anthranilamide and aldehydes were effectively catalyzed by DETA-Fe3O4 in water, and the desired products (2,3-dihydroquinazoline-4(1H)-ones) were afforded in admirable yields. Catalysis research under aqueous medium (water) also makes this synthetic protocol ideal and fascinating from the environmental point of view. The amine catalyst can be magnetically recovered after the reaction and can be reused many times without appreciable decrease in activity.

The preparation and application of fiber catalysts have attracted much attention. However, research on the effect of the micro-environment of fiber catalysts on the catalytic activities though of special importance is limited. In this work, a novel strategy for the synthesis of phosphoric acid-functionalized polyacrylonitrile fibers with a polarity tunable surface micro-environment by hydrophobic groups for one-pot C-C and C-N bond formation reactions is reported. The special hydrophobic surface micro-environment of the fiber catalysts is proven to promote the catalytic activities impressively in cyclocondensation of β-ketoesters with 2-aminobenzamides, the Knoevenagel condensation as well as the multi-component Biginelli reactions in green solvents. Both the surface synergy of the catalytic sites and hydrophobic auxiliary groups (benzyl or n-butyl) in the surface of fiber catalysts and interface acceleration in reaction medium play an important role in the highly efficient promotion of catalytic activity. Thereby a surface synergistic mechanism is proposed to explain the micro-environment effect. In addition, the fiber catalysts could be simply separated from the reaction system using tweezers and directly used in the next cycle without further treatment. Importantly, even after 10 reaction cycles in water or ethanol, there is no significant loss in their catalytic activity. The results indicate that the phosphoric acid functionalized fibers show green and sustainable potential for industrial production.

Bromine source immobilized on magnetic nanoparticles functionalized with diethylenetriamine was successfully synthesized and characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, vibrating sample magnetometry, thermogravimetric analysis and X-ray diffraction. The catalytic activity in the synthesis of 2,3-dihydroquinazoline-4(1H)-one and polyhydroquinoline derivatives and in Knoevenagel condensation was studied. The bromine catalyst can be magnetically recovered and reused several times without significant loss of its catalytic activity. All products were obtained in high to excellent yields.

Herein, an operationally facile and efficient Knoevenagel reaction catalyzed by porous hierarchical MgO/Mg(OH)2 is presented. Condensation of various aldehydes with malononitrile proceeds under mild conditions and gives the target products with

A series of model push-pull molecules with linear, quadrupolar, and tripodal arrangements, a varyingly substituted amino donor, two acceptors, and a partially extended π-system has been prepared. Two peripheral electron acceptors, namely N,N′-dibutylbarbituric acid and dicyanovinyl, were employed. The fundamental properties of 24 push-pull chromophores were investigated by differential scanning calorimetry, electrochemistry, one-photon absorption spectroscopy, photoinduced piezooptics, and were supported by DFT calculations. Thorough structure-property relationships were elucidated, while a significant influence of the structural arrangement/branching on the electronic and optical properties has been revealed. The fundamental optoelectronic properties of push-pull molecules are affected by their arrangement (linear/quadrupolar/tripodal), the peripheral acceptor attached, extension and planarization of the π-system, and also by the type of auxiliary N-substituent.

The present invention relates to a novel bipolar aryl vinyl compound, nano-probe particles including the same, a contrast agent using the same, and an imaging method thereof. The novel bipolar aryl vinyl compound can adjust the solid-state fluorescence (S

The significance of intermolecular classical and non-classical H-bonding interactions in the stabilization of a naphthalene core based conformationally rigid cleft-shaped 1,5-dioxocin (BNAP) is presented here. The importance of H-bonding interactions to a

A variety of 4H-chromenes, benzochromenes, 4,5-dihydropyrano[3,2-c]chromenes, 4H-pyran-3-carboxylates, and 3,4-disubstituted isoxazol-5(4H)-ones have been synthesized in high yields by using potassium hydrogen phthalate (KHP) as an inexpensive, commercially available catalyst. It was found that the three-component tandem reaction enabled synthesis of pyran-annulated heterocycles in water at 50 °C. 3,4-Disubstituted isoxazol-5(4H)-ones were synthesized by use of 10 mol% KHP in water at room temperature. Also, treatment of methylene-containing compounds (malononitrile or ethyl cyanoacetate) with aromatic aldehydes in the presence of 5 mol% KHP resulted in α,β-unsaturated nitriles. The procedure is an easily performed, straightforward method for synthesis of a variety of pyran-annulated compounds, isoxazol-5(4H)-one-containing heterocycles, and Knoevenagel adducts. The reaction is safe, uses mild conditions, and is environmentally benign. Other notable advantages are reuse of the catalyst, no use of hazardous organic solvents, and ease of work-up.

We present the large single crystal growth of a series of donor-π-acceptor (D-π-A) push-pull chromophores; 4-N,N-dimethylamino-β-nitrostyrene (1), 2-(4-(dimethylamino)benzylidene)malononitrile (2), ethyl 2-cyano-3-(4-(dimethylamino)phenyl)acrylate (3) and

Abstract The composite of Al2O3-SiO2 and Al2O3-SiO2-MgO nanocomposite were synthesized by sol-gel method and FT-IR, XRD, FE-SEM, EDAX, TEM, and BET surface area analysis were used to charac

A series of molecular complexes have been designed, synthesized and used as organo-catalysts for the first time for very efficient Knoevenagel condensation. Molecular complexes are thermally stable, easily recyclable, and have a low cost of preparation. T

Solid phase synthesis of poly(propylene imine) dendrimer is described. An iterative synthesis including double Michael addition of acrylonitrile to the primary amino groups on crosslinked polystyrene support followed by reduction of nitrile groups to amin

A mesoporous silica-supported zinc oxide catalyst was successfully synthesized by directly grinding zinc nitrate into the as-prepared Al-Containing SBA-15 occluded with template and characterized by powder X-ray diffraction (XRD), BET nitrogen adsorption-

The deposition of β-amyloid (Aβ) plaques in the parenchymal and cortical brain is accepted as the main pathological hallmark of Alzheimer's disease (AD); however, early detection of AD still presents a challenge. With the assistance of molecular imaging t

The Knoevenagel condensation between aromatic aldehydes and malononitrile, barbituric acid or 1,3-dimethylbarbituric acid with ethane-1,2-diammonium hydrogen sulfate (EDAHS) in aqueous micellar media, using sodium dodecyl sulfate is described. EDAHS was found to be a highly active and stable Bronsted acidic ionic liquid catalyst under the reaction conditions. Graphical Abstract: [Figure not available: see fulltext.].

Peptide inhibitors of insulin-regulated aminopeptidase (IRAP) enhance fear avoidance and spatial memory and accelerate spatial learning in a number of memory paradigms. Using a virtual screening approach, a series of benzopyran compounds was identified th

Molecular diversity generation through reversible component exchange has acquired great importance in the last decade with the development of dynamic covalent chemistry. We explore here the recombination of components linked by C=C and C=N bonds through reversible double-bond formation, and cleavage in C=C/C=C and C=C/C=N exchange processes. The reversibility of the Knoevenagel reaction has been explored, and C=C/C=C C/C exchanges have been achieved among different benzylidenes, under organocatalysis by secondary amines such as L-proline. The substituents of these benzylidenes were shown to play a very important role in the kinetics of the exchange reactions. L-Proline is also used to catalyze the reversible C=C/C=C exchange between Knoevenagel derivatives of barbituric acid and malononitrile. Finally, the interconversion between Knoevenagel derivatives of dimethylbarbituric acid and imines (C=C/C=N exchange) has been studied and was found to occur rapidly in the absence of catalyst. The results of this study pave the way for the extension of dynamic combinatorial chemistry based on C=C/C=C and C=C/C=N exchange systems.

Molybdenum hexacarbonyl activated with pyridine or morpholine catalyzes the condensation of malononitrile with ketones and aldehydes at 140 C, which leads to alkylidenemalononitriles in 75-100% yield.

Synthesis of 2-benzylidenemalononitrile and 1Hand 4H-chromenes derivatives was improved using sulfonic acid functionalized silica (SiO2-Pr- SO3H) as an efficient heterogeneous solid acid catalyst. 1H-and 4H-Chromenes prepared via a s

Zirconia nanoparticles were synthesized by the non-hydrolytic thermal decomposition of zirconyl chloride octahydrate in the presence of oleylamine and oleic acid. The nanoparticles were characterized by XRD, HR-TEM and EDAX techniques. TEM observation con

A simple, eco-friendly and economic method for Knoevenagel condensation of substituted aromatic as well as heteroaromatic aldehydes with malononitrile catalyzed by pineapple juice at room temperature in the absence of any organic solvent is described.

A novel methodology for facile production of α-cyano chalcones under microwave irradiation is described. Utilizing a Knoevenagel condensation between benzoylacetonitriles and aromatic aldehydes, substituted chalcones are generated via a 15-min, one-pot synthesis. Diversification of aromatic groups, including electron-withdrawing, electron-donating, and heterocyclic substitutions, has led to the isolation of over twenty colored, solid chalcone products. Furthermore the methodology can be extended to the synthesis of benzylidenemalononitriles as well as methyl and ethyl α-cyano cinnamates.

A simple and efficient protocol for Knoevenagel condensation has been developed in the presence of diazabicyclo[5.4.0]undec-7-ene (DBU)/water complex. A widely range of carbonyl compounds (aliphatic and aromatic aldehydes, ketones) could react smoothly with methylene active ingredients (malononitrile, ethyl cyanoacetate, diethyl malonate and acetylacetone), which can not proceed by conven- tional catalyst. Other significant features of this method include readily work-up, good recyclability of catalytic system and short reaction time.