Synthesis of Ag-Cu-Ni Nanoparticles Stabilized on Functionalized g-C3N4 and Investigation of Its Catalytic Activity in the A3-Coupling Reaction.

In the present research, using ethylenediamine and hydrazine hydrate as the capping and reducing agents in this investigation, respectively, Ag-Cu-Ni NPs were immobilized on the functionalized g-C3N4 surface. This nanocatalyst was studied in terms of its catalytic activities for the A3-coupling reaction to synthesize propargylamine derivatives. According to the results, in the presence of 1 mL of toluene as the solvent and 20 mg of the g-C3N4-TCT-2AEDSEA-Ag-Cu-Ni nanocatalyst, the maximum efficiency of the nanocatalyst occurred at a temperature of 80 °C. Products were purified using thin-layer chromatography plates (silica gel) by employing n-hexane/ethyl acetate with a 90:10 ratio. In addition, the prominent benefits of the synthesized nanocatalyst include its high yields of the product, cost-effectiveness, recyclability, and easy separation. The novelty of the catalyst is due to the presence of Ag-Cu-Ni nanoparticles at the same time in the structure of the functionalized g-C3N4 substrate. So, Ag-Cu-Ni can be strongly connected to the substrate. The structure of the synthesized nanocatalyst was characterized using Fourier transformed infrared spectroscopy, X-ray powder diffraction, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, vibrating-sample magnetometry, and transmission electron microscopy.

Palladium nanoparticles supported on ionic liquid and glucosamine-modified magnetic iron oxide as a catalyst in reduction reactions.

A magnetic nanocomposite comprising imidazolium ionic liquid and glucosamine is successfully synthesized and used for stabilization of Pd nanoparticles. This new material, Fe3O4@SiO2@IL/GA-Pd, is fully characterized and applied as a catalyst in the reduction of nitroaromatic compounds to desired amines at room temperature. Also, the reductive degradation of organic dyes such as methylene blue (MB), methyl orange (MO), and rhodamine B (RhB) is studied and compared with another previous publications. The survey of the stabilization of the palladium catalytic entities is described demonstrating the separation ability and recycling of them. In addition, TEM, XRD, and VSM analyses of the recycled catalyst confirmed its stability.

Thermoplastic starch/bentonite clay nanocomposite reinforced with vitamin B2: Physicochemical characteristics and release behavior.

This study presents the development and characterization of a nanocomposite material, consisting of thermoplastic starch (TPS) reinforced with bentonite clay (BC) and encapsulated with vitamin B2 (VB). The research is motivated by the potential of TPS as a renewable and biodegradable substitute for petroleum-based materials in the biopolymer industry. The effects of VB on the physicochemical properties of TPS/BC films, including mechanical and thermal properties, water uptake, and weight loss in water, were investigated. In addition, the surface morphology and chemical composition of the TPS samples were analyzed using high-resolution SEM microscopy and EDS, providing insight into the structure-property relationship of the nanocomposites. The results showed that the addition of VB significantly increased the tensile strength and Young's modulus of TPS/BC films, with the highest values observed for nanocomposites containing 5 php of VB and 3 php of BC. Furthermore, the release of VB was controlled by the BC content, with higher BC content leading to lower VB release. These findings demonstrate the potential of TPS/BC/VB nanocomposites as environmentally friendly materials with improved mechanical properties and controlled release of VB, which can have significant applications in the biopolymer industry.

Magnetic bentonite decorated with Pd nanoparticles and cross-linked polyvinyl pyridine as an efficient nanocatalyst for Suzuki coupling and 4-Nitrophenol reduction reactions.

This study reports the preparation of a novel type of support based on magnetically recyclable bentonite functionalized with divinylbenzene-polyvinyl pyridine (PVP-DVB) for Pd (II) nanocatalyst by a simple cost-effective method. Firstly, the conventional co-precipitation method synthesized Fe3O4 nanoparticles (NPs) onto bentonite sheets. Then the prepared magnetic support surface was functionalized by divinylbenzene-polyvinyl pyridine (PVP-DVB) to create a cross-linked polymer with a high coordination ability with palladium. Repeated nitrogen units in the PVP-DVB polymer chain increase the number of Pd bonds and thus lead to higher performance of the nanocatalyst. Finally, the palladium NPs were simultaneously synthesized and immobilized under mild conditions. The synthesized nanocatalyst was characterized by several methods such as scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, vibrating sample magnetometer, inductively coupled plasma mass spectrometry and thermogravimetric analysis. The efficiency of synthesized heterogeneous nanocatalyst was investigated in Suzuki-Miyaura cross-coupling reactions between a range of aryl halides (X = Cl, Br, I) with phenylboronic acid and in the reduction of 4-nitrophenol (4-NP). Moreover, the synthesized nanocatalyst could be easily recovered and reused several times with an efficiency greater than 90%.

Silver-coated magnetic nanoparticles as an efficient delivery system for the antibiotics trimethoprim and sulfamethoxazole against E. Coli and S. aureus: release kinetics and antimicrobial activity.

Trimethoprim and sulfamethoxazole are prescribed for a broad spectrum of bacteria. However, the use of these medicines is restricted due to the risk of microbial resistance in the body. Nanotechnology is a strategy for overcoming this problem by helping develop novel drug delivery systems. This study aims to assess the ability of Fe3O4/Ag and Fe3O4@SiO2/Ag nanoparticles to improve efficiency of the traditional formulation of trimethoprim and sulfamethoxazole. Fe3O4/Ag and Fe3O4@SiO2/Ag were found to have sphere-like morphologies with average sizes of 33.2 and 35.1 nm, respectively. The values of the zeta potential for the pure sulfamethoxazole and trimethoprim were -30.6 and -10.0 mV, respectively, which increased to zero or even larger positive values after being conjugated with the NPs. The study of the release kinetics showed that 64.7% of the medicines were released from the carriers within 40 days. The values of MIC for sulfamethoxazole, trimethoprim, Fe3O4/Ag/sulfamethoxazole, Fe3O4/Ag/trimethoprim, Fe3O4@SiO2/Ag/sulfamethoxazole, and Fe3O4@SiO2/Ag/trimethoprim against Escherichia coli were calculated to be 12, 9, 4, 4, 4, and 4 µg/mL, respectively. Besides, the relevant values against Staphylococcus aureus were measured to be 12, 9, 4, 4, 3, and 2 µg/mL, respectively. The use of synthesized nanomaterials for the delivery of these antibiotics leads to smaller doses compared to their traditional forms.

Biosynthesis of Au nanoparticles supported on Fe3O4@polyaniline as a heterogeneous and reusable magnetic nanocatalyst for reduction of the azo dyes at ambient temperature.

In this research Au nanoparticles, supported on Fe3O4@polyaniline as a magnetic nanocatalyst, was synthesized and its performance has been evaluated to reduce Methylene Blue (MB) and Methyl Orange (MO) from aqueous solutions. Gold nanoparticles, as a nanocatalyst with excellent activity, were prepared through the reduction of Au3+ using a wild herbal extract (Allium Sp) without any toxic chemical compounds and harmful materials. The synthesized Fe3O4@PANI-Au magnetic nanocatalyst was characterized by different instruments. To investigate the effect of nanocatalyst concentration on the degradation rate of azo dyes, two different catalyst concentrations were used at ambient temperature. According to the carried out calculations, degradation reaction of azo dyes with NaBH4 in presence of the nanocatalyst is 103 to 104 times faster than degradation without using the catalyst.

Synthesis and characterization of Ni(II) complex functionalized silica-based magnetic nanocatalyst and its application in C-N and C-C cross-coupling reactions.

A new magnetically recoverable silica-based nickel(II) nanocatalyst was synthesized by a simple cost-effective procedure, which was characterized by TEM, SEM, XRD, VSM analysis, and FT-IR spectrophotometry. The catalytic activity of the prepared Ni(II) nanocatalyst was tested in two complementary reactions: C-N Chan-Lam cross-coupling of phenylboronic acid with aryl amines and C-C Suzuki-Miyaura cross-coupling reaction of phenylboronic acid with aryl halides. The catalyst was easily recovered by magnetic separation and reused for five times. It demonstrated better catalytic activity in the C-N Chan-Lam reaction compared to C-C Suzuki-Miyaura reaction. Ease of recovery and reusability up to five cycles without noticeable loss of performance in the C-N cross-coupling reaction make the present protocol beneficial both industrially and environmentally. In this paper, a new magnetically recoverable silica-based nickel(II) nanocatalyst was synthesized and applied in two complementary reactions: C-C Suzuki-Miyaura reaction and C-N Chan-Lam reaction. The difference in catalytic activity makes it possible to use this catalyst for cases that are prone to both reactions and selectively create the desired product.

Flash flow pyrolysis: mimicking flash vacuum pyrolysis in a high-temperature/high-pressure liquid-phase microreactor environment.

Flash vacuum pyrolysis (FVP) is a gas-phase continuous-flow technique where a substrate is sublimed through a hot quartz tube under high vacuum at temperatures of 400-1100 °C. Thermal activation occurs mainly by molecule-wall collisions with contact times in the region of milliseconds. As a preparative method, FVP is used mainly to induce intramolecular high-temperature transformations leading to products that cannot easily be obtained by other methods. It is demonstrated herein that liquid-phase high-temperature/high-pressure (high-T/p) microreactor conditions (160-350 °C, 90-180 bar) employing near- or supercritical fluids as reaction media can mimic the results obtained using preparative gas-phase FVP protocols. The high-T/p liquid-phase "flash flow pyrolysis" (FFP) technique was applied to the thermolysis of Meldrum's acid derivatives, pyrrole-2,3-diones, and pyrrole-2-carboxylic esters, producing the expected target heterocycles in high yields with residence times between 10 s and 10 min. The exact control over flow rate (and thus residence time) using the liquid-phase FFP method allows a tuning of reaction selectivities not easily achievable using FVP. Since the solution-phase FFP method does not require the substrate to be volatile any more--a major limitation in classical FVP--the transformations become readily scalable, allowing higher productivities and space-time yields compared with gas-phase protocols. Differential scanning calorimetry measurements and extensive DFT calculations provided essential information on pyrolysis energy barriers and the involved reaction mechanisms. A correlation between computed activation energies and experimental gas-phase FVP (molecule-wall collisions) and liquid-phase FFP (molecule-molecule collisions) pyrolysis temperatures was derived.

A convenient one-pot synthesis of 3-amino-2, 5-dihydropyridazine and pyrimidine derivatives in the presence of high surface area MgO as a highly effective heterogeneous base catalyst.

A new and efficient method for the preparation of 3-amino-2,5-dihydropyridazines from three-component reactions of (phenyl-hydrazono)-propan-2-one, aldehydes, and malononitrile or ethyl cyanoacetate in the presence of magnesium oxide (MgO) as a highly effective heterogeneous base catalyst is presented. Also, the three-component reactions of aldehydes, amidine systems, and malononitrile or ethyl cyanoacetate for the formation of 4-amino-5-pyrimidine carbonitrile and pyrimidinone derivatives, respectively, are investigated. The salient features of these methods include high conversions, short reaction times, cleaner reaction profiles, and the use of inexpensive and readily available catalyst.

Effect of opium addiction on lipid profile and atherosclerosis formation in hypercholesterolemic rabbits.

In some Asian and Middle Eastern societies, opium consumption has traditionally been regarded as a way to lower blood lipids and to prevent heart diseases. This could eventually lead to addiction. In this study, the effect of oral opium consumption on serum lipids and atherogenesis in rabbits was investigated. Twenty-eight male New Zealand white rabbits were divided into control, hypercholesterolemic, addicted, and hypercholesterolemic-addicted groups and were studied for 3 months. Serum lipid profile was determined at the beginning of the study and at 1 month intervals thereafter. At the end of the study period, aortic plaque formation was assessed. Compared with control, in the hypercholesterolemic and hypercholesterolemic-addicted groups, cholesterol, triglycerides, and low-density lipoprotein cholesterol levels were significantly increased (P<0.01). The increases in lipids and lesion areas in the aorta were higher in hypercholesterolemic-addicted than hypercholesterolemic group (P<0.05). Our findings suggest that opium consumption can have aggravating effects in atherosclerosis formation related with hypercholesterolemia, mainly affecting lipid profile.

Microwave-assisted synthesis of dihydropyrimidin-2(1H)-ones using graphite supported lanthanum chloride as a mild and efficient catalyst.

Graphite supported lanthanum chloride efficiently catalyzes the three-component coupling of beta-ketoesters, aldehydes and urea/thiourea to afford corresponding dihydropyrimidinones in good yields under microwave irradiation.

Carboxyketenes from 4-hydroxy-1,3-oxazin-6-ones and Meldrum's acid derivatives.

New 4-hydroxy-1,3-oxazin-6-ones 8 and 16 were prepared from chlorocarbonyl(phenyl)ketene and amides. The flash vacuum thermolysis (FVT) reactions of these compounds and the 4-methoxy derivative 17 were investigated by Ar matrix isolation IR spectroscopy and online mass spectrometry including MS/MS analysis. Carboxy(phenyl)ketene 10 is formed as the major product by thermal fragmentation of 4-hydroxy-1,3-oxazin-6-one 8. This takes place via the unstable 6-hydroxy tautomer 9. Another tautomer, the 5H-isomer 12, leads to the formation of benzoyl isocyanate 13 as a minor product together with phenylketene 14. Carboxy(phenyl)ketene 10 remains detectable at high FVT temperatures but undergoes thermal decarboxylation to phenylketene 14. The same carboxy(phenyl)ketene 10 is also produced in significant amounts by FVT of 5-phenyl-Meldrum's acid 18 via the unstable enol tautomer 19. A small amount of the unsubstituted carboxyketene 20 is observable on FVT of Meldrum's acid 1 itself.

Mesoionic 1,3-oxazinium olates. rearrangement to acylketenes and 3-azabicyclo[3.1.1]heptanetriones.

Metastable but isolable mesoionic 1,3-oxazinium 4-olates 9d-f undergo ring opening to acylketenes 10 at or near room temperature. The ketenes undergo intramolecular criss-cross [2 + 2] cycloaddition to afford 3-azabicyclo[3.1.1]heptanetriones 12. The structure of 12d was established by X-ray crystallography.