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Regenerated silk fibroin (RSF) is a promising candidate for skin repair due to its wound healing properties. RSF films have some drawbacks such as weak mechanical property, low porosity and poor absorption which limits their application as an ideal wound healing dressing. In this study, a novel RSF-based nanohybrid bearing carnosine (Car) intercalated bentonite (CarBen) nanosheets was prepared using solvent casting method and was applied in a second-degree burn wound model. RSF bearing different amounts of CarBen nanosheets (0, 1, 3 and 5 wt%) was prepared and fully characterized. RSF having 5 wt% of the modified Ben (RSF-CarBen5) showed superior mechanical property (ultimate stress of 8.36 ± 01 MPa and ultimate strain of 1501.33 ± 1.24%), and higher absorption capacity (1653.57 ± 0.05%) with favorable porosity (80.27%). RSF-CarBen5 was employed as dressing for healing of second-degree burn wound in rats. Histological evaluation showed considerable inflammation reduction in wound sites compared to the control groups. The wound treated with the nanohybrid showed significant epithelialization and angiogenesis on day 14 post-treatment, compared to the other groups (P

A clean, efficient and mild method is presented for one-pot three-component synthesis of 2-amino-7,7-dimethyl-4-(4-(methylthio)phenyl)-5-oxo-5,6,7,8-tetrahydro-4H-chromene-3-carbonitrile using nickel ferrite magnetic nanoparticles as a recyclable catalyst in green solvent at 40 °C. The structure of the target product was confirmed by FT-IR, 1HNMR, 13CNMR and single crystal X-ray structure analysis. In the present work, the quantum theoretical calculations of the molecular structure of this new compound have been predicted using Density Functional Theory in the solvent DMSO. The geometries of the title compound were optimized by B3LYP/6-31+G* and B3LYP/6-311++G** levels of theory. The electronic spectrum of the title compound in the solvent DMSO was carried out by TDB3LYP/6-311++G** method. Frontier molecular orbitals, molecular electrostatic potential, electronic properties, natural charges and natural bond orbital analysis of the mentioned compound were investigated and discussed by theoretical calculations. In the present work, the frontier molecular orbitals, molecular electrostatic potential, electronic properties, natural charges and Natural Bond Orbital (NBO) analysis of the mentioned compound were investigated and discussed by theoretical calculations.

Cupric oxide (CuO) nanoparticles are synthesized using Henna and copper nitrate as the copper source by the green method at different calcination temperatures. The effect of the amount of Henna extracts on the particle size and the morphology of nanoparticles is characterized by powder X-ray diffraction (XRD) and scanning electron microscopy. This method has many advantages such as nontoxicity, economic viability, easiness to scale up, less time consuming and environment-friendly approach for the synthesis of CuO nanoparticles without using any organic chemicals. The average crystallite size of CuO nanoparticles is calculated using the Scherrer formula. The powder XRD analysis reveals the formation of a monoclinic CuO phase with an average particle size of 22–38 nm. There is good agreement between the data obtained by XRD and microscopic measurements. The particle sizes of the prepared cupric oxide nanoparticles depend on the amount of Henna extracts and calcination temperatures.

Tetramethylguanidine supported onto magnetic Fe3O4 nanoparticles (MNPs-TMG) was prepared and identified by several techniques such as TEM, XRD, SEM, FT-IR and TGA analyses. The synthesized catalyst was utilized as an effective catalyst for aldol reaction between acetone and various aldehydes to achieve β-hydroxy carbonyl compounds in excellent yields. This procedure has several advantages, such as moderate reaction conditions, excellent yields, short reaction time and easy purification of the products. Additionally, supporting this organosuperbase catalyst on magnetic nanoparticles offers a simple method for easy reuse and recovery of the catalyst using an external magnetic field.

N-isocyaniminotriphenylphosphorane (Ph3PNNC) is a type of iminophosphorane which is an important reagent in synthetic organic chemistry and a ligand in metallic complexes. The quantum theoretical calculations were performed for Ph3PNNC by density functional theory (DFT/B3LYP/6-311+G*). Frontier molecular orbitals (FMOs), total density of states (DOS), molecular electrostatic potential (MEP), molecular properties, natural charges, NMR parameters and NBO analysis for N-isocyaniminotriphenylphosphorane (Ph3PNNC) are investigated by theoretical calculations.

A green and highly efficient method has been developed for the synthesis of 2-amino-4H-chromene derivatives in the presence of FeTiO3 as magnetic catalyst via one-pot three-component condensation reaction of aromatic aldehydes, malononitrile and α- or β-naphthol without solvent under microwave irradiation. Mild reaction conditions, short reaction times, simple work-up, use of an economically convenient catalyst, and excellent product yields are the advantageous features of this method. The catalyst can be easily recovered by a simple magnetic separation and can be recycled six times with no significant loss of catalytic activity.

In this work, zinc oxide (ZnO) nanoparticles were synthesized using arabic gum as a biotemplate source by the sol–gel method and its photocatalytic dye degradation ability from aqueous solution was studied. This method has many advantages such as nontoxic, economic viability, ease to scale up, less time consuming and environmental friendly approach for the synthesis of ZnO nanoparticles without using any organic chemicals. Direct blue 129 (DB129) was used as model dye. The synthesized ZnO nanoparticles were characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy, scanning electron microscopy and UV–Visible spectroscopy. The X-ray powder diffraction (XRD) analysis revealed the formation of wurtzite hexagonal phase ZnO with average crystallite size of 10 nm. Photocatalytic dye degradation by ZnO nanoparticles was studied using UV–Vis spectrophotometer. The effects of process parameters like, catalyst dosage, initial dye concentration, and visible light irradiation on dye degradation have been investigated.

A green and efficient method for the preparation of 2-(dibenzylamino)-2-aryl acetamide derivatives via a three-component reaction of an isocyanide, dibenzylamine and a phthalaldehyde derivative in the presence of silica nanoparticles (silica NPs, ca. 42 nm) as a catalyst under solvent free conditions at room temperature is described. The ease of work-up, green chemistry conditions and high yields of the products make this procedure a useful addition to modern synthetic methods. The silica nanoparticles that used in this reaction as a catalyst were prepared by thermal decomposition of rice hulls. Simple, green and cheap method for the preparation of the nanocatalyst represents a major advantage for this process. The structures of these compounds were confirmed by IR, 1 H and 13 C NMR spectroscopy. KEY WORDS : Silica nanoparticles, Nanocatalyst, Isocyanide, Phthalaldehyde Bull. Chem. Soc. Ethiop. 2016 , 30(3), 413-420 DOI: http://dx.doi.org/10.4314/bcse.v30i3.9

Reactions of N-isocyaniminotriphenylphosphorane (NICITPP) with 2-oxopropyl-1-benzenecarbothioate in the presence of aromatic carboxylic acids and primary amines proceed smoothly at room temperature...

A green and convenient protocol is described for the preparation of 1-(alkylamino)-3-(1,3-dioxoisoindolin-2-yl)-2-methyl-1-oxopropan-2-yl benzoates via one-pot three-component reaction between 2-(2-oxopropyl)isoindoline-1,3-dione, an alkyl isocyanide and an aromatic carboxylic acid in water at room temperature. The methods used to follow the reactions are TLC and NMR, which indicated that there is no side product and the products were obtained without any purification. The structures of the products were deduced from their 1H NMR, 13C NMR and IR spectra. The present methodology offers several advantages such as a simple procedure, catalyst-free, mild reaction conditions, high yields, and the absence of any volatile and hazardous organic solvents.

An efficient green protocol for the synthesis of 1,3,4-oxadiazoles derivatives via a one-pot three-component reaction of aromatic carboxylic acids, N-isocyanimino-triphenylphosphorane and ester der...

Reactions of benzoic acid derivatives and (E)-cinnamic acid derivatives with $N,N^{\prime }$ -dialkyl carbodiimide proceed smoothly at room temperature and in neutral conditions to afford N-acylurea derivatives in high yields. The reaction proceeds smoothly and cleanly under mild conditions and no side reactions were observed.

Tetramethylguanidine-functionalized silica-coated iron oxide magnetic nanoparticles as a productive and reusable catalyst have been applied for the one-pot three-component synthesis of furanone derivatives (4a–o). In addition to the characterization of all products by FT-IR, $$^{1}\hbox {HNMR}$$ and $$^{13}\hbox {CNMR}$$ spectroscopy, single-crystal X-ray analysis of ethyl 5-oxo-2-phenyl-4-(phenylamino)-2,5-dihydrofuran-3-carboxylate product has been made. Easy recrystallization and good-to-excellent yields (81–92%) of furanone derivatives are notable characteristics of this procedure. The catalyst identification was performed using FT-IR, XRD, SEM, TEM and TGA techniques. It is worth noting that the nanocatalyst can be recycled with an external magnet and reused for several times. SYNOPSIS In this procedure, tetramethylguanidine-functionalized silica-coated iron oxide magnetic nanoparticles $$(\hbox {Fe}_{3}\hbox {O}_{4}\hbox {-TMG})$$ has been employed as an efficient, eco-friendly and reusable catalyst for one-pot three-component synthesis of furanone derivatives in a green solvent at $$40\,^{\circ }\hbox {C}$$ . The use of magnetic nanocatalyst is the superior feature of this method.

Reactions of N-isocyaniminotriphenylphosphorane with cyclopentanone have been studied in the presence of aromatic carboxylic acids and primary amines, proceeds smoothly at room temperature under neutral conditions to afford sterically congested 1,3,4-oxadiazole derivatives by an intramolecular Aza-Wittig cyclization in CH2Cl2 in excellent yields. The structures of the products were deduced from their IR, Mass, ¹H NMR, and ¹³C NMR spectra. The reaction proceeds smoothly and cleanly under mild conditions and no side reactions were observed. The method offers a mild, simple, and efficient route for the preparation of fully substituted 1,3,4-oxadiazoles from cyclopentanone, primary amines, N-isocyaniminotriphenylphosphorane and aromatic carboxylic acids. Easy work-up, high yields and fairly mild reaction conditions make it a useful procedure in comparison to the modern synthetic methodologies.

Protonation of the highly reactive 1:1 intermediate produced in the reaction between triphenylphosphine and an acetylenic ester by a N-H acid (4-phenylphthalazin-1(2 H)-one, 5,5-diphenylimidazolidine-2,4-dione) leads to the formation of a vinyltriphenylphosphonium salt. The cation of the salt undergoes an addition reaction with the counter anion in CH2Cl2 at room temperature to yield the corresponding stabilized phosphorus ylide. Elimination of triphenylphosphine from the stabilized phosphorus ylides leads to the formation of corresponding electron-poor N-vinylated heterocycles in moderate to high yields (67–95%). The reaction is completely regio- and stereoselective.

Reaction of N-isocyaniminotriphenylphosphorane with biacetyl in the presence of a carboxylic acid in water proceeds smoothly at RT (20–26°C) and neutral conditions to afford sterically congested 1,3,4-oxadiazole derivatives in high yields. The reaction proceeds smoothly and clearly under mild conditions and no side reactions were observed.

To address the obstacles facing the use of palladium-based homogeneous and heterogeneous catalysts in C─C cross-coupling reactions, a novel semi-heterogeneous support was developed based on hyperbranched poly(ethylene glycol)-block-poly(citric acid)-functionalized Fe3O4 magnetic nanoparticles (Fe3O4@PCA-b-PEG). Because of the surface modification of the Fe3O4 nanoparticles with amphiphilic and hyperbranched polymers (PCA-b-PEG), these hybrid materials are not only soluble in a wide range of solvents (e.g. water, ethanol and dimethylformamide) but also are able to trap Pd2+ ions via complex formation of free carboxyl groups of the PCA dendrimer with metal ions. The reduction of trapped palladium ions in the dendritic shell of Fe3O4@PCA-b-PEG leads to immobilized palladium nanoparticles. The morphology and structural features of the catalyst were characterized using various microscopic and spectroscopic techniques. The catalyst was effectively used in the palladium-catalysed Mizoroki–Heck coupling reaction in water as a green solvent. In addition, the catalyst can be easily recovered from the reaction mixture by applying an external magnetic field and reused for more than ten consecutive cycles without much loss in activity, exhibiting an example of a sustainable and green methodology.