Green synthesis and characterization of α-Mn2O3 nanoparticles for antibacterial activity and efficient visible-light photocatalysis.

In this study, green synthesis, characterizations, photocatalytic performance, and antibacterial applications of α-Mn2O3 nanoparticles are reported. The synthesized nanoparticles were characterized by Fourier transform infrared spectroscopy (FT-IR), powder X-ray diffraction (XRD), transmission electron microscope (TEM), Scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), Brunauer Emmett Teller (BET), Electrochemical Impedance Spectroscopy (EIS), Photoluminescence (PL), and Differential reflectance spectroscopy (DRS) analysis. The investigation verified that the α-Mn2O3 nanoparticles possessed a cubic structure, with a crystallite size of 23 nm. The SEM and TEM techniques were used to study the nanoscale morphology of α- Mn2O3 nanoparticles, which were found to be spherical with a size of 30 nm. Moreover, the surface area was obtained as 149.9 m2 g-1 utilizing BET analysis, and the band gap was determined to be 1.98 eV by DRS analysis. The photocatalysis performance of the α-Mn2O3 NPs was evaluated for degrading Eriochrome Black T (EBT) dye under visible light and degradation efficiency was 96% in 90 min. The photodegradation mechanism of EBT dye was clarified with the use of radical scavenger agents, and the degradation pathway was confirmed through Liquid Chromatography-Mass Spectrometry (LC-MS) analysis. Additionally, the produced nanoparticles could be extracted from the solution and continued to exhibit photocatalysis even after five repeated runs under the same optimal conditions. Also, the antibacterial activity of green synthesized α-Mn2O3 nanoparticles was investigated by using the broth microdilution method towards Enterococcus faecalis ATCC 29212 (Gram-positive), Staphylococcus aureus ATCC 29213 (Gram-positive), Salmonella typhimurium ATCC 14028 (Gram-negative), Klebsiella pneumoniae ATCC 7881 (Gram-negative), Escherichia coli ATCC 25922 (Gram-negative), Proteus mirabilis ATCC 7002 (Gram-negative), and Pseudomonas aeruginosa ATCC 27853 (Gram-negative) bacterial strains.

Oral immunotherapy for Helicobacter pylori: Can it be trusted? A systematic review.

BACKGROUND: Helicobacter pylori (H. pylori) is a rod-shaped, gram-negative, microaerophilic bacterium that can be identified by gram staining. Its relationship with cancer is significant since it is involved in approximately 80% of gastric cancers and 5.5% of all malignant cancers. Two lines of treatment have been defined for H. pylori, but almost 40% of patients do not respond to the first line. Recent trials have investigated oral Immunotherapy as a new treatment method. The aim of this systematic review was to investigate the potential effects of oral Immunotherapy on eradication rate of H. pylori in human studies. METHODS: The systematic review was performed according to PRISMA guidelines. We searched online databases, including Scopus, PubMed, and Web of Science (ISI). Our search strategy was limited to English articles and studies on human populations that use oral immunotherapy for H. pylori. RESULTS: The total number of primary research records in different databases was 2775. After removing duplicate articles (n = 870), we excluded 1829 for reasons including non-human studies, irrelevance to our study objective, non-English language, or lack of information. Of the remaining 76 articles, only seven had sufficient information, and the rest were excluded. The studies were divided into two groups: those that used bovine antibody and those that used immunoglobulin Y to eradicate H. pylori. CONCLUSION: In the group of Immunoglobulin Y, three out of four studies suggest that using Immunoglobulin Y for the treatment of H. pylori infection is significant. However, the group using bovine antibody for the treatment of H. pylori infection has various results, as two out of three studies concluded that bovine antibody therapy is not significant.

PEI-based functional materials: Fabrication techniques, properties, and biomedical applications.

Cationic polymers have recently attracted considerable interest as research breakthroughs for various industrial and biomedical applications. They are particularly interesting due to their highly positive charges, acceptable physicochemical properties, and ability to undergo further modifications, making them attractive candidates for biomedical applications. Polyethyleneimines (PEIs), as the most extensively utilized polymers, are one of the valuable and prominent classes of polycations. Owing to their flexible polymeric chains, broad molecular weight (MW) distribution, and repetitive structural units, their customization for functional composites is more feasible. The specific beneficial attributes of PEIs could be introduced by purposeful functionalization or modification, long service life, biocompatibility, and distinct geometry. Therefore, PEIs have significant potential in biotechnology, medicine, and bioscience. In this review, we present the advances in PEI-based nanomaterials, their transfection efficiency, and their toxicity over the past few years. Furthermore, the potential and suitability of PEIs for various applications are highlighted and discussed in detail. This review aims to inspire readers to investigate innovative approaches for the design and development of next-generation PEI-based nanomaterials possessing cutting-edge functionalities and appealing characteristics.

Nanomaterials Based Micro/Nanoelectromechanical System (MEMS and NEMS) Devices.

The micro- and nanoelectromechanical system (MEMS and NEMS) devices based on two-dimensional (2D) materials reveal novel functionalities and higher sensitivity compared to their silicon-base counterparts. Unique properties of 2D materials boost the demand for 2D material-based nanoelectromechanical devices and sensing. During the last decades, using suspended 2D membranes integrated with MEMS and NEMS emerged high-performance sensitivities in mass and gas sensors, accelerometers, pressure sensors, and microphones. Actively sensing minute changes in the surrounding environment is provided by means of MEMS/NEMS sensors, such as sensing in passive modes of small changes in momentum, temperature, and strain. In this review, we discuss the materials preparation methods, electronic, optical, and mechanical properties of 2D materials used in NEMS and MEMS devices, fabrication routes besides device operation principles.

Recent advances in the application of alkynes in multicomponent reactions.

Alkynes have two active positions to carry out chemical reactions: C[triple bond, length as m-dash]C and C-H. These two positions are involved and activated in different reactions using different reagents. In this study, we investigated the reactions of alkynes that are involved in multi-component reactions through the C-C and C-H positions and examined the progress and gaps of each reaction by carefully studying the mechanism of the reactions. Firstly, we investigated and analyzed the reactions involving the C[triple bond, length as m-dash]C position of alkynes, including the reactions between derivatives of alkynes with RN3, sulfur compounds (RSO2R', DMSO, S8, DABCO(SO2)2 and DABSO), barbituric acids, aldehydes and amines, COOH, α-diazoesters or ketones, and isocyanides. Then, we examined and analyzed the important reactions involving the C-H position of alkynes and the progress and gaps in these reactions, including the reaction between alkyne derivatives with amines and aldehydes for the synthesis of propargylamines, the reaction between alkynes with CO2 and the reaction between alkynes with CO.

Palladium-based pseudohomogeneous catalyst for highly selective aerobic oxidation of benzylic alcohols to aldehydes.

This study presents a novel class of pseudohomogeneous catalysts (PHC) based on carbon quantum dots functionalized with terpyridine ligands (CQDs-Tpy) to immobilize and stabilize palladium nanoparticles (Pd NPs). Extensive characterization techniques clearly confirmed the successful stabilization of Pd NPs on CQDs-Tpy. The effectiveness of the catalyst was demonstrated in the selective aerobic oxidation of primary and secondary of benzylic alcohols to aldehydes in the absence of additives and phase transfer catalyst (PTC). Remarkably, the reactions predominantly yielded aldehydes without further oxidation to carboxylic acids. By employing low catalyst loadings (0.13 mol%), high conversions (up to 89%) and excellent selectivity (> 99%) of the aldehyde derivatives were achieved. Moreover, the CQDs-Tpy/Pd NPs catalyst displayed suitable catalytic activity and recyclability, offering potential economic advantages. This promising approach opens up new opportunities in the field of catalysis for designing subnanometric metal-based PHCs.

Photocatalytic removal of imidacloprid pesticide from wastewater using CdS QDs passivated by CQDs containing thiol groups.

Over the past decade, CdS QDs have become versatile semiconductors. Surface modification of CdS QDs has become an interesting case study, as it can eliminate surface defects and improve their photochemical properties. In this study, we report a new strategy of using carbon quantum dots containing a large number of thiol groups (CQDs-SH) as a passivating agent for the stabilization of CdS quantum dots (QDs). Various characterization techniques have clearly revealed that the CdS QDs have been successfully passivated by CQDs-SH. The photocatalytic performance of CQDs-SH/CdS QDs was investigated for the degradation of the insecticide imidacloprid from an aqueous solution. Parameters affecting the photodegradation process, including the light source, photocatalyst amount, initial concentration of the pollutant, radiation time, pH, oxidizing agent, and temperature, were investigated. Furthermore, the HPLC technique was applied to quantitatively analyze imidacloprid and its degradation products. The results of the HPLC analysis revealed that under simulated visible light at pH 9, imidacloprid scarcely existed after 90 min of irradiation (90.13% degradation). The LC-MS method was also used to detect the degradation products and investigate the mechanism of photodegradation of the pesticide. The results showed that the CQDs-SH/CdS QDs composite was a promising photocatalyst for the degradation of imidacloprid in wastewater.

Schiff Base Complex of Copper Immobilized on Core-Shell Magnetic Nanoparticles Catalyzed One-Pot Syntheses of Polyhydroquinoline Derivatives under Mild Conditions Supported by a DFT Study.

We synthesized a stable and reusable Schiff base complex of copper immobilized on core-shell magnetic nanoparticles [Cu(II)-SB/GPTMS@SiO2@Fe3O4] with simple, efficient, and available materials. A variety of characterization analyses including Fourier transform infrared (FT-IR), X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET), thermogravimetric analysis (TGA), X-ray diffraction (XRD), vibrating-sample magnetometry (VSM), energy-dispersive X-ray spectrometry (EDX), and inductively coupled plasma (ICP) confirm that our synthesized nanocatalyst was obtained. The particle size distribution from the TEM image was obtained in the range of 42-55 nm. The existence of cupric species (Cu2+) in the catalyst was determined with XPS analysis and clearly indicated two peaks at 933.7 and 953.7 eV for Cu 2p3/2 and Cu 2p1/2, respectively. BET results showed that our catalyst synthesized with a mesoporous structure and with a specific area of 48.82 m2 g-1. After detailed characterization, the resulting nanocatalyst exhibited excellent catalytic performance for the explored catalytic reactions in the one-pot synthesis of polyhydroquinoline derivatives by the Hantzsch reaction of dimedone, ethyl acetoacetate, ammonium acetate, and various aldehydes under sustainable and mild conditions. The corresponding products 5a-l are achieved in yields of 88-97%. Additionally, density functional theory (DFT) calculations were carried out to investigate the electrostatic potential root (ESP), natural bond orbital (NBO), and molecular orbitals (MOs), drawing the reaction mechanism using the total energy of the reactant and product and the study of structural parameters.

Boron-rich hybrid BCN nanoribbons for highly ambient uptake of H2S, HF, NH3, CO, CO2 toxic gases.

Nanomaterials-based gas sensors are widely applied for the monitoring and fast detection of hazardous gases owing to their sensitivity and selectivity. Hydrogen sulfide (H2S), hydrogen fluoride (HF), ammonia (NH3), and carbon monoxide/dioxide (CO/CO2) produced from petroleum fields, sewage, mines, and gasoline are harmful for both human life and environment. With an increase in the emission of these toxic compounds, their real-time monitoring and efficient adsorbent application and storage are very necessary. To this end, we investigated the adsorption characteristic and sensitivity factor of these five toxic gases on armchair and zigzag hybrid boron-carbon-nitride (BCN) nanoribbons with/without boron-rich (B-rich) defects using first principle calculation, where 25%, 33%, and 50% carbon concentration were considered. Our findings reveal that B-rich nanoribbons have strong adsorption energy, charge transfer, and structural deformation owing to the double acceptor of B-rich defects. Moreover, the zigzag and armchair forms of these hybrid BCN nanoribbons show physical adsorption, altering their band gap and phase transition after adsorbing these toxic gases, where B-rich nanoribbons possess high sensitivity to NH3 and CO among other gases. Furthermore, B-rich hybrid nanoribbons have higher CO2 adsorption energy than the standard free energy of CO2 at room temperature. This study suggests that hybrid BCN nanoribbons and B-rich defected structures can be good candidates for the uptake and storage of toxic gases, helping experimental groups to design efficient ambient gas sensors.

Terahertz linear/non-linear anomalous Hall conductivity of moiré TMD hetero-nanoribbons as topological valleytronics materials.

Twisted moiré van der Waals heterostructures hold promise to provide a robust quantum simulation platform for strongly correlated materials and realize elusive states of matter such as topological states in the laboratory. We demonstrated that the moiré bands of twisted transition metal dichalcogenide (TMD) hetero-nanoribbons exhibit non-trivial topological order due to the tendency of valence and conduction band states in K valleys to form giant band gaps when spin-orbit coupling (SOC) is taken into account. Among the features of twisted WS[Formula: see text]/MoS[Formula: see text] and WSe[Formula: see text]/MoSe[Formula: see text], we found that the heavy fermions associated with the topological flat bands and the presence of strongly correlated states, enhance anomalous Hall conductivity (AHC) away from the magic angle. By band analysis, we showed that the topmost conduction bands from the ± K-valleys are perfectly flat and carry a spin/valley Chern number. Moreover, we showed that the non-linear anomalous Hall effect in moiré TMD hetero-nanoribbons can be used to manipulate terahertz (THz) radiation. Our findings establish twisted heterostructures of group-VI TMD nanoribbons as a tunable platform for engineering topological valley quantum phases and THz non-linear Hall conductivity.

Cationic micelle delivery of a multi-epitope vaccine candidate derived from tumor-associated antigens, causing regression in established CT26 colorectal tumors in mice.

Among all the cancers, colorectal cancer (CRC) has the third mortality rank in both genders. Cancer vaccines have shown promising results in boosting patients' immune systems to fight cancer. Using the IEDB database, we predicted mouse MHC-I (H2-Ld) binding epitopes from four tumor-associated antigens (APC, KRAS, TP53, and PIK3CA) and designed a multi-epitope vaccine. We expressed the candidate vaccine and encapsulated it into the cationic micelle with polyethyleneimine conjugated to oleic acid as its building blocks. We studied tumor inhibition effect, cytokine production, and lymphocyte proliferation in the mouse CRC model after vaccination. Our finding illustrated significant tumor growth inhibition in mouse models treated with the candidate nanovaccine. Besides the significant release of IFN-γ and IL-4 by immunized mouse spleen T-lymphocytes, T-cell proliferation assay results confirmed effective immune response after the vaccination. These results demonstrate the potential therapeutic effects of nanovaccines and could be a possible approach to CRC immunotherapy.

Chiral Pseudohomogeneous Catalyst Based on Amphiphilic Carbon Quantum Dots for the Enantioselective Kharasch-Sosnovsky Reaction.

The term "chiral pseudohomogeneous catalyst (PHC)" denotes a novel concept that characterizes subnanometric particles exhibiting atomic-level chirality. The PHC based on chiral amphiphilic carbon quantum dots possesses distinctive features that combine the strengths of both homogeneous and heterogeneous catalysts, thereby heralding a significant breakthrough in the fields of asymmetric synthesis and medicinal chemistry. To the best of our knowledge, this is the first and the only reported research of a chiral PHC that demonstrates exceptional performance in controlling the enantioselectivity of the Kharasch-Sosnovsky reaction, yielding the corresponding products in high conversion (95%) with a moderate enantiomeric excess (75%). Notably, the chiral information on l-tryptophan can be effectively transferred from the outer shell of the nanosized catalyst, thereby inducing enantioselectivity in C-H activation and subsequent C-O forming events. Additionally, we have investigated the impact of various factors on the allylic oxidation reaction, including the amount, diversity, and hydrophilic/hydrophobic nature of the catalyst, as well as the influence of the solvent, Cu salts, temperature, and the type of alkene and perester, in order to comprehensively explore the reaction conditions. Furthermore, the catalyst can be readily recycled from the reaction medium, making this PHC a promising innovation that can significantly impact practical applications. In summary, this breakthrough can be aptly described as a "Golden Gate" due to its unparalleled potential to open up novel avenues for research and innovation.

Amygdalin/chitosan-polyvinyl alcohol/cerium-tannic acid hydrogel as biodegradable long-time implant for cancer recurrence care applications: An in vitro study.

Cancer recurrence following surgery is a serious and worrying problem for the patient. Common treatment strategies, such as chemotherapy, radiotherapy, and surgery, are restricted because of low uptake of the drugs, poor pharmacokinetic properties, and toxicity issues for healthy tissues. The development of engineering platforms for improving the postoperative treatment of cancer can help solve this problem. In this study, the ceria-tannic acid nanoparticles (CeTA-NPs) were successfully synthesized and characterized. Chitosan-polyvinyl/alcohol (CS-PVA) hydrogels containing CeTA NPs (CS-PVA/CeTA) and amygdalin as an anticancer substance were fabricated using freeze-thaw and immersion-drying techniques. The swelling and degradation behaviors, antibacterial activity, and biocompatibility of as-prepared hydrogel were done. The apoptotic effects of amygdalin/CS-PVA/CeTA hydrogel were evaluated by flow cytometry technique on a human colorectal cancer (SW-480) cell line. The CeTA-NPs were investigated as antibacterial and cross-linker agents for greater stability of the hydrogel network. The CS-PVA/CeTA hydrogel demonstrated good safety and antibacterial activity. The results of swelling and biodegradation suggest that CS-PVA/CeTA hydrogels can inspire long-time application. The anticancer effects of the amygdalin/CS-PVA/CeTA hydrogel were confirmed by apoptosis results. Hence, amygdalin/CS-PVA/CeTA hydrogel can be a promising candidate for long-time biomedical application.

Recyclable mesalamine-functionalized magnetic nanoparticles (mesalamine/GPTMS@SiO2@Fe3O4) for tandem Knoevenagel-Michael cyclocondensation: grinding technique for the synthesis of biologically active 2-amino-4H-benzo[b]pyran derivatives.

In the present study, mesalamine-functionalized on magnetic nanoparticles (mesalamine/GPTMS@SiO2@Fe3O4) is fabricated as an efficient and magnetically recoverable nanocatalyst. The as-prepared nanocatalyst was successfully synthesized in three steps using a convenient and low-cost method via modification of the surface of Fe3O4 nanoparticles with silica and GPTMS, respectively, to afford GPTMS@SiO2@Fe3O4. Finally, treatment with mesalamine as a powerful antioxidant generates the final nanocatalyst. Then, its structure was characterized by FT-IR, SEM, TEM, EDX, XRD, BET, VSM, and TGA techniques. The average size was found to be approximately 38 nm using TEM analysis and the average crystallite size was found to be approximately 27.02 nm using XRD analysis. In particular, the synthesized nanocatalyst exhibited strong thermal stability up to 400 °C and high magnetization properties. The activity of the synthesized nanocatalyst was evaluated in the tandem Knoevenagel-Michael cyclocondensation of various aromatic aldehydes, dimedone and malononitrile under a dry grinding method at room temperature to provide biologically active 2-amino-4H-benzo[b]pyran derivatives products in a short time with good yields. The presented procedure offers several advantages including gram-scale synthesis, good green chemistry metrics (GCM), easy fabrication of the catalyst, atom economy (AE), no use of column chromatography, and avoiding the generation of toxic materials. Furthermore, the nanocatalyst can be reused for 8 cycles with no loss of performance by using an external magnet.

A copper(ii) complex containing pyridine-2-carbaldehyde and its direct binding onto ethylenediamine functionalized with Fe3O4@SiO2 nanoparticles for catalytic applications.

In the present study, a copper(ii) complex containing a pyridine-2-carbaldehyde ligand and its direct binding onto ethylenediamine functionalized with Fe3O4@SiO2 nanoparticles [Cu(ii)-Schiff base-(CH2)3-SiO2@Fe3O4] as a heterogeneous magnetic nanocatalyst can be easily prepared using a multi-step method. Next, the structural and magnetic properties of the synthesized nanoparticles were identified using Fourier-transform infrared spectroscopy (FT-IR), inductively coupled plasma (ICP), vibrating-sample magnetometry (VSM), transmission electron microscopy (TEM), field-emission scanning electron microscopy (FE-SEM), thermogravimetric analysis (TGA), PXRD (Powder X-ray diffraction), Brunauer-Emmett-Teller (BET), and energy-dispersive X-ray spectrometry (EDX) techniques. TEM images reveal that the average particle size distribution was found to be in the range of 45-55 nm with spherical shape. The PXRD analysis indicated that the crystallite size was found to be 35.2 nm. The synthesized nanocatalyst exhibited a very good catalytic ability in the synthesis reaction of pyran derivatives and 2-benzylidenemalononitrile derivatives. Product 2-amino-7,7-dimethyl-4-(4-nitrophenyl)-5-oxo-5,6,7,8-tetrahydrobenzo[b]pyran 4e was achieved in 97% yield with a TON of 129.3 and a TOF of 646.6 h-1 and product 2-(4-cyanobenzylidene)malononitrile 3j was achieved in 96% yield with a TON of 128 and a TOF of 984.6 h-1. In addition, the synthesized nanocatalyst was easily separated from the reaction mixture by a magnet and used 7 consecutive times without significant loss of catalytic activity. Also, leaching of copper metal from the synthesized nanocatalyst was very insignificant for this reaction.

Preparation of high-performance supercapacitor electrode with nanocomposite of CuO/NCNO flower-like.

Due to the importance of energy storage systems based on supercapacitors, various studies have been conducted. In this research CuO, NCNO and the flower like CuO/NCNO have been studied as a novel materials in this field. The resulte showed that the synthesized CuO nanostructutes have flower like morphology which studied by FE-SEM analisis. Further, the XRD pattern confirmed the crystalline properties of the CuO/NCNO nanocomposite, and the Raman verified the functional groups and vibrations of the components of CuO/NCNO nanocomposite. In a two-electrode system at a current density of 4 A/g, the capacitance, power density, and energy density were 450 F/g, 3200 W/kg, and 98 Wh/kg, respectively. The charge transfer resistances of CuO and NCNO/CuO electrodes obtained 8 and 2 Ω respectively, which show that the conductivity and supercapacitive properties of nanocomposite are better than pure components. Also, the stability and low charge transfer resistance are other advantages obtained in a two-symmetrical electrode investigation. The stability investigation showed that after 3000 consecutive cycles, only 4% of the initial capacitance of the CuO/NCNO electrode decreased.

In vitro Characterization of Polyethyleneimine-Oleic Acid Cationic Micelle as a Novel Protein Carrier.

Background: Nanotechnology has introduced valuable carriers for vaccine delivery. The success of vaccination depends on many factors, such as the intact and safe presentation of vaccine candidates to immune cells. We have conjugated branched PEI-2k and oleic acid (OL) as the building block of the cationic micelle. We aimed to introduce a novel carrier for vaccine candidates. Materials and Methods: We conjugated polyethyleneimine and OL (POA) to synthesize the building blocks of cationic micelles. The critical micelle concentration (CMC), size and zeta potential of micelles, and their stability in 60 days were determined. Loading, encapsulation efficiency, and in vitro release study were assessed using bovine serum albumin (BSA) as a protein model. Furthermore, the cytotoxicity and hemocompatibility of developed nanosized micelles were evaluated to ascertain the biocompatibility of fabricated micelles. Cell uptake of cationic micelles in the macrophage cell line was also followed up. Results: The conjugation of two polymer parts was confirmed by Fourier transform infrared spectroscopy and 1H nuclear magnetic resonance techniques. The CMC of the developed micelles was around 5.62 × 10-8 mg/ ml, whereas the loading and encapsulation efficiencies were 16.5% and 70%, respectively. The size and zeta potential of the cationic micelles were 96.53 ± 18.53 nm and 68.3 mV, respectively. The release of BSA from POA micelles after 8 and 72 hours was 8.5% and 82%, respectively. Finally, fluorescence microscopy showed that the prepared micelles were successfully and effectively taken up by RAW264.7 cells. Conclusion: These results may provide a cutting-edge vaccine delivery solution and open up a new avenue for future vaccine research.

SO3H-Functionalized Epoxy-Immobilized Fe3O4 Core-Shell Magnetic Nanoparticles as an Efficient, Reusable, and Eco-Friendly Catalyst for the Sustainable and Green Synthesis of Pyran and Pyrrolidinone Derivatives.

A SO3H-functionalized epoxy-immobilized Fe3O4 core-shell magnetic nanocatalyst was prepared through a simple three-step procedure, and it was identified by various analyses such as Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), differential thermal gravity (DTG), Brunauer-Emmett-Teller (BET) analysis, transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), thermogravimetric analysis (TGA), vibration sample magnetometry (VSM), and powder X-ray diffraction (PXRD). BET analysis showed that the as-prepared nanocatalyst was synthesized with a mesoporous structure and high specific area (35.45 m2 g-1). The TEM image clearly showed that the particle size distribution was in the range of 47-65 nm. The designed magnetic nanocatalyst was used successfully in the synthesis of pyran derivatives via the reaction of dimedone, malononitrile, and various aromatic aldehydes and synthesis of pyrrolidinone derivatives via the reaction of various aromatic aldehydes, aniline, and diethyl acetylenedicarboxylate. The nanocatalyst was simply isolated from the reaction mixture utilizing an external magnet and reused several times according to the model reactions without significant loss in its efficiency.

Picolylamine-Ni(ii) complex attached on 1,3,5-triazine-immobilized silica-coated Fe3O4 core/shell magnetic nanoparticles as an environmentally friendly and recyclable catalyst for the one-pot synthesis of substituted pyridine derivatives.

In the current study, an environmentally friendly and facile method was proposed for designing and constructing a catalyst with Ni(ii) attached to a picolylamine complex on 1,3,5-triazine-immobilized Fe3O4 core-shell magnetic nanoparticles (NiII-picolylamine/TCT/APTES@SiO2@Fe3O4) via a stepwise procedure. The as-synthesized nanocatalyst was identified and characterized via Fourier-transform infrared (FT-IR), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), vibrating-sample magnetometry (VSM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), field-emission scanning electron microscopy (FE-SEM), inductively coupled plasma (ICP), and energy-dispersive X-ray spectrometry (EDX). The obtained results from the BET analysis indicated that the synthesized nanocatalyst had high specific area (53.61 m2 g-1) and mesoporous structure. TEM observations confirmed the particle size distribution was in the range 23-33 nm. Moreover, the binding energy peaks observed at 855.8 and 864.9 eV in the XPS analysis confirmed the successful and stable attachment of Ni(ii) on the surface of the picolylamine/TCT/APTES@SiO2@Fe3O4. The as-fabricated catalyst was used to produce pyridine derivatives by the one-pot pseudo-four component reaction of malononitrile, thiophenol, and a variety of aldehyde derivatives under solvent-free conditions or EG at 80 °C. The highest yield achieved was 97% for compound 4d in EG at 80 °C with a TOF of 823 h-1 and TON of 107. It was found that the used catalyst was recyclable for eight consecutive cycles. On the basis of ICP analysis, the results indicated that the Ni leaching was approximately 1%.