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1.
RSC Adv ; 13(30): 20530-20556, 2023 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-37435379

RESUMO

Recently, the preparation and applications of magnetic nanostructures have attracted increasing attention in nanocatalysis studies, and magnetic nanoparticle (MNP) functionalized catalysts have been applied in important reactions such as Suzuki-Miyaura and Heck couplings. The modified nanocomposites demonstrate significant catalytic efficiency and excellent benefits in the context of catalyst recovery methods. This review discusses the recent modified magnetic nanocomposites in the field of catalytic applications along with the synthetic processes that are usually employed.

2.
Sci Rep ; 11(1): 12362, 2021 06 11.
Artigo em Inglês | MEDLINE | ID: mdl-34117274

RESUMO

A new and efficient catalyst has been designed and prepared via in situ immobilization of Au NPs fabricated polydopamine (PDA)-shelled Fe3O4 nanoparticle anchored over graphene oxide (GO) (GO/Fe3O4@PDA/Au). This novel, architecturally interesting magnetic nanocomposite was fully characterized using different analytical techniques such as Field Emission Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy, elemental mapping, Transmission Electron Microscopy, Fourier Transformed Infrared Spectroscopy, X-ray Diffraction and Inductively Coupled Plasma-Atomic Electron Spectroscopy. Catalytic activity of this material was successfully explored in the reduction of nitroarenes to their corresponding substituted anilines, using NaBH4 as reducing agent at ambient conditions. The most significant merits for this protocol were smooth and clean catalysis at room temperature with excellent productivity, sustainable conditions, ease of separation of catalyst from the reaction mixture by using a magnetic bar and most importantly reusability of the catalyst at least 8 times without any pre-activation, minimum loss of activity and considerable leaching.

3.
Sci Rep ; 11(1): 4515, 2021 02 25.
Artigo em Inglês | MEDLINE | ID: mdl-33633123

RESUMO

This current research is based on a bio-inspired procedure for the synthesis of biomolecule functionalized hybrid magnetic nanocomposite with the Fe3O4 NPs at core and Pd NPs at outer shell. The central idea was the initial modification of magnetic NP by the phytochemicals from Fritillaria imperialis flower extract, which was further exploited in the green reduction of Pd2+ ions into Pd NPs, in situ. The flower extract also acted as a capping agent for the obtained Pd/Fe3O4 composite without the need of additional toxic reagents. The as-synthesized Fe3O4@Fritillaria/Pd nanocomposite was methodically characterized over different physicochemical measures like FT-IR, ICP-AES, FESEM, EDX, TEM, XPS and VSM analysis. Thereafter, its catalytic potential was evaluated in the reduction of various nitrobenzenes to arylamines applying hydrazine hydrate as reductant in ethanol/water (1:2) medium under mild conditions. Furthermore, the nanocatalyst was retrieved using a bar magnet and recycled several times without considerable leaching or loss of activity. This green, bio-inspired ligand-free protocol has remarkable advantages like environmental friendliness, high yields, easy workup and reusability of the catalyst.

4.
Sci Rep ; 11(1): 1983, 2021 01 21.
Artigo em Inglês | MEDLINE | ID: mdl-33479340

RESUMO

Plant derived biogenic synthesis of nanoparticles (NP) has been the recent trend in material science as featured sustainable catalysts. A great deal of the current nanocatalytic research has been oriented on the bio-inspired green catalysts based on their wide applicability. In this context, CuO NPs are synthesized following a green approach using an herbal tea (Stachys Lavandulifolia) flower extract. The phytochemicals contained in it were used asthe internal reductant without applying harsh chemicals or strong heat. The derived nanoparticles also got stabilized by the biomolecular capping. The as-synthesized CuO NPs was characterized over FT-IR, FE-SEM, EDS, TEM, XRD, TGA and UV-Vis spectroscopy. These NPs were exploited as a competent catalyst in the aryl and heteroaryl C-heteroatom (N, O, S) cross coupling reactions affording outstanding yields. The nanocatalyst was isolated and recycled in 8 consecutive runs with reproducible catalytic activity. Rigidity of the CuO/S. Lavandulifolia nanocomposite was further justified by leaching test and heterogeneity test.

5.
Int J Biol Macromol ; 160: 1252-1262, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32485247

RESUMO

The present report represents the synthesis of a novel Pd NPs immobilized over a natural polysaccharide (pectin) coated Fe3O4 magnetic nanocomposite material (Fe3O4@pectin/Pd) for investigating the cardiovascular protective effects. The biomolecular functionalization not only stabilizes the ferrite nanoparticles from agglomeration but also provides an environment for the biogenic reduction of Pd2+ ions. This protocol is a promising breakthrough for the synthesis of a quasi-heterogeneous catalyst, a bridge between heterogeneous and homogeneous medium. The structure, morphology and physicochemical properties of the material were characterized utilizing various analytical techniques like FT-IR, FE-SEM, TEM, VSM, EDX-elemental mapping, ICP, EDX and XPS. The catalyst showed excellent reactivity in C-C and C-N cross coupling reactions via Suzuki and Buchwald-Hartwig reactions respectively. An array of different biphenyls and aryl amines were then procured by reactions of various aryl halides with phenylboronic acid or secondary amines over the catalyst affording good to excellent yields. The catalyst was easily recoverable using an external magnet and thereafter recycled for several trials with insignificant palladium leaching or loss in catalytic performance. To investigate the cardiovascular protective activities of catalyst, the MTT assay was done on Human Aortic Endothelial Cells (HAEC), Human Coronary Artery Endothelial Cells (HCAEC), and Human Pulmonary Artery Endothelial Cells (HPAEC) cell lines. Nanocatalyst-treated cell cutlers significantly (p ≤ 0.01) decreased the caspase-3 activity, and DNA fragmentation. It raised the cell viability and mitochondrial membrane potential in the high concentration of Mitoxantrone-treated HAEC, HCAEC, and HPAEC cells. According to the above findings, nanocatalyst can be administrated as a cardiovascular protective drug for the treatment of cardiovascular diseases after approving in the clinical trial studies in humans.


Assuntos
Cardiotônicos/síntese química , Compostos Férricos/química , Nanopartículas Metálicas/química , Paládio/química , Pectinas/química , Apoptose , Cardiotônicos/farmacologia , Catálise , Células Cultivadas , Células Endoteliais/efeitos dos fármacos , Células Endoteliais/metabolismo , Endotélio Vascular/citologia , Humanos
6.
Carbohydr Polym ; 235: 115966, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-32122500

RESUMO

Chitosan is a linear polysaccharide and non-toxic bioactive polymer with a wide variety of applications due to its functional properties such as ease of modification, and biodegradability. In this study, a green protocol for in situ fabrication of ultrafine Pd nanoparticles on chitosan-encapsulated Fe3O4/SiO2-NH2 nanoparticles, without the use of any toxic reducing agents, is described. The catalytic activity of Fe3O4/SiO2-NH2@CS/Pd nanocomposite was investigated through Suzuki-Miyaura coupling to synthesize biaryl derivatives, and reduction of 4-nitrophenol to 4-aminophenol. The core-shell nanoparticle modified with chitosan highly stabilizes the exterior Pd NPs. Leaching test was performed to assure heterogeneity of the catalyst. The magnetically retrievable catalyst was recycled up to eight times in both reactions without significant loss in its activity.

7.
Mater Sci Eng C Mater Biol Appl ; 105: 110031, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31546457

RESUMO

Silver (Ag) nanoparticles (NPs) were prepared through a biological procedure where the essential oils of orange peel were used as a capper and reductant agent. Characterization of these Ag/EOs orange NPs was carried out using X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), UV-visible spectroscopy, and thermogravimetric analysis (TGA). These NPs were utilized as an effective heterogeneous nanocatalyst for the three-component reaction of amines, aldehydes and alkynes (A3 coupling). Different ranges with high performance were achieved for propargylamines. Moreover, the isolation and recovery of Ag/EOs orange NPs were very easy, efficient and cost effective.


Assuntos
Citrus sinensis/química , Química Verde/métodos , Nanopartículas Metálicas/química , Nanopartículas/química , Óleos Voláteis/química , Óleos/química , Prata/química , Água/química , Catálise , Nanopartículas/ultraestrutura , Espectroscopia Fotoeletrônica , Espectrometria por Raios X , Espectrofotometria Ultravioleta , Espectroscopia de Infravermelho com Transformada de Fourier , Termogravimetria , Difração de Raios X
8.
Mater Sci Eng C Mater Biol Appl ; 104: 109919, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31499980

RESUMO

An eco-friendly biosynthesized Pd NP anchored Thymbra spicata extract-modified graphene oxide (Pd NPs/rGO-T. spicata) nanohybrid material has been introduced. Initially, the herb, Thymbra spicata extract was immobilized on the surface of GO via their natural adhering capability. The polyphenolic function grafted in situ prepared RGO acted as the natural reductant of Pd precursor. The as-prepared nanocomposite (Pd NPs/rGO-T. spicata) was characterized using Fourier transform infrared (FTIR), UV-vis, X-ray diffraction (XRD), inductively coupled plasma (ICP), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS), high resolution transmission electron microscopy (HRTEM), Fast Fourier Transform (FFT), Raman spectroscopy and EDX elemental mapping techniques. It has been observed that the Pd NPs with perfect crystal structure, uniform shape and size were dispersed homogeneously on the rGO surface. The material showed excellent water dispersibility due to the hydrophilicity of biomolecules attached over them, which is very essential in heterogeneous catalysis. The T. spicata contained biomolecules served as effective capping, reducing and stabilizing agents for the uniform immobilization of Pd precursors on graphene sheet surface without aggregation. The catalytic activity of this nano hybrid was assessed comprehensively in the cyanation of aryl halides with a wide range of substrates using K4[Fe(CN)6] as a cheap source of cyanide. The model reaction resulted outstanding catalytic performance with a great reusability of the catalysis.


Assuntos
Cianetos/química , Grafite/química , Halogênios/química , Nanopartículas Metálicas/química , Paládio/química , Extratos Vegetais/química , Catálise , Lamiaceae/ultraestrutura , Nanopartículas Metálicas/ultraestrutura , Espectrometria por Raios X , Espectrofotometria Ultravioleta , Espectroscopia de Infravermelho com Transformada de Fourier , Análise Espectral Raman , Difração de Raios X
9.
ACS Omega ; 4(9): 13991-14003, 2019 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-31497717

RESUMO

This research suggests a green method for synthesizing hybrid magnetic nanocomposites that can be used as a reductant and a stabilizing agent for immobilizing metal nanoparticles (NPs). The central idea is the modification of magnetic NPs using Rubia tinctorum extract, which consists of numerous carbonyl and phenolic hydroxyl functional groups to increase adsorption of metals and chelate silver ions, and decrease the adsorption of silver ions by Ag NPs, in situ. Thus, the suggested catalyst preparation process does not require toxic reagents, additional reductants, and intricate instruments. To show the effectiveness of the plant extract in reducing and immobilizing Ag NPs, the structural, morphological, and physicochemical features of the particles are studied using Fourier-transform infrared spectroscopy, inductively coupled plasma atomic emission spectroscopy, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, high-resolution transmission electron microscopy, vibrating sample magnetometry, X-ray diffraction analysis, and X-ray photoelectron spectroscopy. One of the advantages of the suggested method is to reduce the size of the magnetic NPs from 15-20 to 2-5 nm, in the presence of the extract. Additionally, the prepared Fe3O4@R. tinctorum/Ag nanocatalyst is demonstrated to exhibit a very high activity in the catalysis of the three-component reaction of aldehydes, amines, and alkynes (A3 coupling) with good to high yields of diverse propargylamines. Moreover, the nanocatalyst can be recovered several times with no considerable leaching or loss of performance.

10.
BMC Pediatr ; 19(1): 229, 2019 07 09.
Artigo em Inglês | MEDLINE | ID: mdl-31288771

RESUMO

BACKGROUND: Manganese is a critical trace element that not only has antioxidant properties, but also is essential for various metabolic pathways and neurotransmitters production. However, it can be toxic at high levels, particularly in the central nervous system. Manganese intoxication can be acquired, but an inherited form due to autosomal-recessive mutations in the SLC30A10 gene encoding a Mn transporter protein has also been reported recently. These mutations are associated with significant failure of manganese excretion and its storage in the liver, brain (especially basal ganglia), and other peripheral tissues, resulting in toxicity. CASE PRESENTATION: A 10-year-old boy from consanguineous parents presented with a history of progressive truncal instability, gait difficulty, and frequent falls for 2 months. He had dystonia, rigidity, ataxia, dysarthria, bradykinesia and a plethoric skin. Investigations showed polycythemia, low serum iron and ferritin levels, and increased total iron binding capacity. A brain MRI revealed symmetric hyperintensities in the basal ganglia and dentate nucleuses on TI images that were suggestive of brain metal deposition together with clinical manifestations. Serum calcium and copper levels were normal, while the manganese level was significantly higher than normal values. There was no history of environmental overexposure to manganese. Genetic testing showed a homozygous missense mutation in SLC30A10 (c.C1006T, p.His336Tyr) and Sanger sequencing confirmed a homozygous state in the proband and a heterozygous state in the parents. Regular treatment with monthly infusions of disodium calcium edetate and oral iron compounds resulted in decreased serum manganese and hemoglobin levels to normal values, significant resolution of MRI lesions, and partial improvement of neurological symptoms during 6 months of follow-up. CONCLUSION: The syndrome of hepatic cirrhosis, dystonia, polycythemia, and hypermanganesemia caused by SLC30A10 mutation is a treatable inherited metal deposition syndrome. The patient may only have pure neurological without hepatic manifestations. Although this is a rare and potentially fatal inborn error of metabolism, early diagnosis and continuous chelation therapy might improve the symptoms and prevent disease progression.


Assuntos
Proteínas de Transporte de Cátions/genética , Manganês/metabolismo , Doenças Metabólicas/genética , Mutação de Sentido Incorreto , Mutação Puntual , Encéfalo/patologia , Terapia por Quelação , Criança , Consanguinidade , Ácido Edético/uso terapêutico , Genótipo , Humanos , Compostos de Ferro/uso terapêutico , Imageamento por Ressonância Magnética , Masculino , Doenças Metabólicas/diagnóstico por imagem , Doenças Metabólicas/tratamento farmacológico , Neuroimagem , Sequenciamento do Exoma
11.
Mater Sci Eng C Mater Biol Appl ; 98: 584-593, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30813061

RESUMO

This work describes (i) an eco-friendly approach for in situ immobilization of Pd nanoparticles on the surface of Fe3O4 nanoparticles, with help of green tea extract and ultrasound irradiations, without using any toxic reducing agents and (ii) development of ultrasound assisted simple protocol for synthesis of biphenyl compounds. The structural, morphological and physicochemical characteristics of the catalyst were determined by different analytical methods including inductively coupled plasma (ICP) analysis, Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and vibrating sample magnetometry (VSM). Catalytic performance of Pd/Fe3O4 NPs as magnetic and heterogeneous catalyst was evaluated in synthesis of various biphenyl compounds throughout Suzuki coupling reactions by using the ultrasound-assisted method that was developed in this study. The Pd/Fe3O4 NPs demonstrated a noticeable catalytic activity by giving high product yields. Furthermore, the heterogeneous nanocatalyst was successfully recovered up to six times without significant activity loss. Additionally, with respect to conventional coupling reactions, the ultrasound-assisted synthesis reactions presented the advantages of green conditions, short reaction times, high yields and easier work-up.


Assuntos
Compostos de Bifenilo/síntese química , Magnetismo , Nanopartículas Metálicas/química , Nanopartículas/química , Paládio/química , Extratos Vegetais/química , Chá/química , Ondas Ultrassônicas , Catálise , Compostos Férricos/química , Cinética , Espectroscopia Fotoeletrônica , Espectrometria por Raios X , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura , Difração de Raios X
12.
Mater Sci Eng C Mater Biol Appl ; 97: 624-631, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30678949

RESUMO

Surface modification of Fe3O4 nanoparticle with thiol groups was used for the immobilization of silver nano-particles to produce Fe3O4/SiO2-Pr-S-Ag NPs. The prepared catalyst was characterized by Inductively coupled plasma (ICP), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectrum (EDS), vibrating sample magnetometer (VSM) and Fourier transform infrared (FTIR) analysis. In this fabrication, thio-groups played an important role as a capping and stabilizing agent for Ag nanoparticles. Fe3O4/SiO2-Pr-S-Ag NPs show high catalytic activity as recyclable nanocatalyst toward degradation of 4-nitrophenol (4-NP), rhodamine B (RhB), and Methylene blue (MB) in the presence of NaBH4 in water at room temperature. With the help of UV-Vis spectroscopy, catalysis reactions were examined. Furthermore, these reactions followed the pseudo-first order rate equation.


Assuntos
Corantes/química , Óxido Ferroso-Férrico/química , Nanopartículas de Magnetita/química , Dióxido de Silício/química , Prata/química , Compostos de Sulfidrila/química , Boroidretos/química , Catálise , Cinética , Azul de Metileno/química , Nitrofenóis/química , Oxirredução , Rodaminas/química , Temperatura
13.
Mater Sci Eng C Mater Biol Appl ; 96: 310-318, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30606538

RESUMO

In current research, the multi walled carbon nanotubes was functionalized with mercapto-melamine groups by covalent grafting of f-CNT with ethylenediamine, cyanuric chloride and 2-mercaptoethanol for introducing mercapto functional groups on the surface of nanotube. Consequently, the thiolated MWCNTs were applied to deposing Pd nanoparticles. The results of FTIR, Raman spectroscopy, powder XRD, energy dispersive spectroscopy (EDS), wavelength-dispersive X-ray spectroscopy (WDX) and CHN analysis showed the successful synthesis of nanocatalyst. The scanning and transmission electron microscopes (SEM and TEM) were used to study the morphologies of the nanocatalyst. Moreover, the (MWCNTs/CC-SH/Pd) nanocatalyst was effectively applied in Buchwald-Hartwig C-N cross coupling reaction with wide variety of functionalized substrates. A variety of aryl amines were prepared through reaction of aryl halides (chloride, bromide and iodide) and amines in high yields. Remarkably, the new catalyst could be reused for six recycles without change in its catalytic activity.


Assuntos
Nanopartículas Metálicas/química , Nanotubos de Carbono/química , Nitrogênio/química , Paládio/química , Catálise
14.
Int J Nanomedicine ; 13: 3965-3973, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30022820

RESUMO

BACKGROUND: Noble metal nanoparticles, due to their good physicochemical properties, have been exploited in biological applications. Among these metals, nanosilver has attracted great attention because of its optical properties and broad-spectrum antimicrobial activities with no drug tolerance. PURPOSE: The present study has attempted to conduct chemical synthesis of Fe3O4@PEG-Ag core/shell nanocomposites in aqueous solutions through co-precipitation of Fe3+ and Fe2+ ions, encapsulating the iron oxide core by poly (ethylene-glycol) (PEG) improve its hydrophilicity and biocompatibility, and immobilizing silver ions by application of NaBH4 as a reducing agent. PATIENTS AND METHODS: The synthesized structures were characterized by Fourier-transform infrared (FT-IR), field emission scanning electron microscopy, energy-dispersive X-ray spectrum, wavelength-dispersive X-ray, vibrating sample magnetometer, inductively coupled plasma-mass spectrometry and transmission electron microscopy methods. Antimicrobial activity of the nanostructures against Staphylococcus aureus, Escherichia coli and Candida albicans was evaluated by broth microdilution based on the methods suggested by Clinical Laboratory Standard Institute. Furthermore, the nanocomposite was tested for possible anti-parasitic effects against Leishmania major promastigotes by MTT assay. Also, its impacts on bacterial cell morphology were defined using atomic force microscopy. Moreover, toxicity of the nanostructure related to animal cell line was determined based on MTT assay. RESULTS: In general, the synthesized core/shell nanostructure can demonstrate noticeable activity against the evaluated representative microorganisms while its toxicity against animal cell line is not considerable. CONCLUSION: This nanostructure can be applied as a smart drug delivery system with the help of an external magnetic field or it can be used as a powerful antibiotic agent along with other antibiotics that can form a shell on its structure.


Assuntos
Anti-Infecciosos/farmacologia , Nanopartículas de Magnetita/química , Nanopartículas Metálicas/química , Nanocompostos/química , Polietilenoglicóis/química , Prata/farmacologia , Animais , Sobrevivência Celular/efeitos dos fármacos , Escherichia coli/citologia , Escherichia coli/efeitos dos fármacos , Leishmania/efeitos dos fármacos , Nanopartículas de Magnetita/ultraestrutura , Testes de Sensibilidade Microbiana , Nanocompostos/ultraestrutura , Prata/química , Espectroscopia de Infravermelho com Transformada de Fourier , Staphylococcus aureus/citologia , Staphylococcus aureus/efeitos dos fármacos
15.
Mater Sci Eng C Mater Biol Appl ; 90: 57-66, 2018 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-29853127

RESUMO

For first time, we designed an environment friendly technique novel hybrid magnetic nanocomposite with the potency of both reducing and stabilizing agent for immobilization of metal nanoparticles. Stachys lavandulifolia extract having a lot of carbonyl and phenolic hydroxyl functional groups can be applied in the Fe3O4 NPs modification. Furthermore, in aqueous solution, the complexation feasibility of polyphenols with silver ions can enhance the capacity and surface properties of the Fe3O4@S. lavandulifolia NPs for sorbent and in situ reduction of silver ions. So, as both the stabilizing and reducing agent, the novel magnetic nano-sorbent (Fe3O4@S. lavandulifolia NPs) has potential ability for silver nano particles immobilization to create a novel magnetic silver nanocatalyst. So that, no additional reductants, toxic reagents and intricate instruments are needed to prepare the catalyst. The morphology, structure, and physicochemical properties were elucidated by several analytical methods like, field emission scanning electron microscope (FESEM), high resolution transmission electron microscopy (HRTEM) images, energy-dispersive X-ray spectroscopy (EDS), vibrating sample magnetometer (VSM), X-ray diffraction analysis (XRD), X-ray photoelectron spectroscopy (XPS), FT-IR spectroscopy, and inductively coupled plasma (ICP). As recyclable nanocatalyst, Fe3O4@S. lavandulifolia/Ag indicated high catalytic activity for 4-nitrophenol (4-NP) reduction at ambient temperature. Ultimately, the Fe3O4@S. lavandulifolia/Ag antibacterial properties was examined against two bacteria (Staphylococcus aureus (Staph. aureus) and Escherichia coli (E. coli)) and indicated its antibacterial activities against gram negative (E. coli) bacteria and gram positive (Staph. aureus).


Assuntos
Antibacterianos/química , Antibacterianos/farmacologia , Compostos Férricos/química , Nanopartículas Metálicas/química , Nitrofenóis/química , Prata/química , Stachys/química , Chás de Ervas/análise , Escherichia coli/efeitos dos fármacos , Escherichia coli/ultraestrutura , Microscopia Eletrônica de Transmissão , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/ultraestrutura
16.
Int J Biol Macromol ; 113: 186-194, 2018 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-29476850

RESUMO

This article is devoted to synthesis of a new magnetic interphase palladium catalyst that has been immobilized on chitosan-biguanidine coated-magnetic Fe3O4 nanoparticles [Pd(0/II)/CS-bigua@Fe3O4]. Such surface functionalization of magnetic particles is a promising method to bridge the gap between heterogeneous and homogeneous catalysis approaches. The structure, morphology, and physicochemical properties of the particles were characterized through different analytical techniques, including Fourier transformed infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), wavelength-dispersive X-ray spectroscopy (WDX), inductively coupled plasma (ICP), energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). Pd(0/II)/CS-bigua@Fe3O4 demonstrated high catalytic activity as a recyclable nanocatalyst toward Suzuki-Miyaura cross-coupling reactions, at room temperature. Furthermore, the catalyst could be recovered and reused several times with no significant palladium leaching or change in its activity.


Assuntos
Quitosana/química , Guanidina/química , Nanopartículas de Magnetita/química , Paládio/química , Catálise
17.
RSC Adv ; 8(37): 21020-21028, 2018 06 05.
Artigo em Inglês | MEDLINE | ID: mdl-35542342

RESUMO

The current study suggests a convenient synthesis of in situ, ecofriendly and well-dispersed palladium nanoparticles with narrow and small dimension distributions on a graphene oxide (GO) surface using a Rosa canina fruit extract as a stabilizer and reducing agent without the addition of any other stabilizers or surfactants. The as-synthesized nanocatalyst (Pd NPs/RGO) was assessed with XRD, UV-vis, FE-SEM, EDS, TEM, ICP and WDX. The obtained heterogeneous nanocatalyst showed catalytic performance for reducing 4-nitrophenol (4-NP), rhodamine B (RhB) and methylene blue (MB) at ambient temperature in an ecofriendly medium. The catalyst was retained by centrifugation and reused several times with no considerable change in its catalytic performance.

20.
RSC Adv ; 8(67): 38186-38195, 2018 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-35559075

RESUMO

High reaction rate and easy availability make green synthesis of metal nanoparticles noticeable. In the present study, gold nanoparticles with wide applications in different fields were synthesized by an ecofriendly method at room temperature using Stachys lavandulifolia extract as the reducing agent. Properties of the synthesized gold nanoparticles (GNP) were identified by different analytical techniques including: UV-Vis absorption spectroscopy verified presence of Au NPs in the solution while functional groups of its extract and synthesized Au NPs were determined by FT-IR. Its crystalline analysis with a fcc plane was verified by X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS) determined elements in the sample. Surface morphology, diverse shapes and sizes of the Au NPs were shown by scanning electron microscopy (SEM), atomic force microscopy (AFM), and transmission electron microscopy (TEM). Beginning and end destruction temperatures of the Au/S. lavandulifolia NPs were determined by thermal gravimetric analysis (TGA). The Au nanoparticles were capped with extracts, preventing them from oxidation and agglomeration and were used as an efficient heterogeneous nanocatalyst for a three-component reaction of amines, aldehydes, and alkynes (A3 coupling). A diverse range of propargylamines were obtained in good yields. Furthermore, the separation and recycling of Au/S. lavandulifolia NPs was very simple, effective, and economical.

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