Fe3O4@C@MCM41

Scientific Reports volume 13, Article number: 10336 (2023) Cite this article

279 Accesses

2 Altmetric

Metrics details

In this study, preparation, characterization and catalytic application of a novel core–shell structured magnetic with carbon and mesoporous silica shells supported guanidine (Fe3O4@C@MCM41-guanidine) are developed. The Fe3O4@C@MCM41-guanidine was prepared via surfactant directed hydrolysis and condensation of tetraethyl orthosilicate around Fe3O4@C NPs followed by treatment with guanidinium chloride. This nanocomposite was characterized by using Fourier transform infrared spectroscopy, vibrating sample magnetometry, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, thermal gravimetric analysis, wide-angle X-ray diffraction and low-angle X-ray diffraction techniques. This nanocomposite have high thermal, chemical stability, and uniform size. Fe3O4@C@MCM41-guanidine catalyst demonstrated high yield (91–98%) to prepare of Knoevenagel derivatives under the solvent free conditions at room temperature in the shortest time. Also, this catalyst was recovered and reused 10 times without significant decrease in efficiency and stability. Fortunately, an excellent level of yield (98–82%) was observed in the 10 consecutive catalyst cycles.

In recent years, core–shell nanoparticles (NPs) have attracted much attention. The combination of core and shell material, their design and geometry lead to the creation of unique properties in them1,2. In addition, core–shell NPs are planed so that the shell material can improve the oxidative stability, thermal stability or reactivity of the core material or a cheap core material is used to transport the costly shell material3,4,5. Core–shell NPs have many usages in biomedical research6, MRI7,8,9, catalysis10,11,12, drug delivery13, energy harvesting14,15, plasmonic16,17, sensors18,19,20, etc. Much progress has been chance in the development of rational synthetic methods for the production of various core–shell NPs. Among the types of core–shell NPs, mSiO2-coated magnetite (Fe3O4) NPs have attracted the attention of researchers in various fields such as biomedical, sensor, catalyst, etc., due to their illustrious attributes such as unique magnetic response, low cytotoxicity, high colloidal stability, high adsorption capacity, high chemical and thermal stability, high surface area, high colloidal stability and high availability of silanol groups on its surface for any modification3,21,22. Some of recently developed mSiO2-coated magnetite NPs are Fe3O4@MCM-41-SB/Pd3, Fe3O4@SiO2@MCM41-IL/WO42−23, Fe3O4@nSiO2@mSiO2–Fe24, Fe3O4@MCM-41/Melamine25, Fe3O4@SiO2@mSiO2@TiO226, Fe3O4@mSiO2@BiOBr27 and Fe3O4@mSiO2@mLDH28. Meanwhile, carbon and polymer-coated NPs have also attracted a lot of attention due to their unusual attributes. Specifically, magnetite NPs coated by carbon show a high conductivity and are very engrossing for energy-storage and catalysis applications29,30,31,32. Some recently developed examples are Fe3O4@CN@HM33, Fe@C@Mo6O1834, Au-Fe3O4@Carbon35, Fe3O4@C@Au36 and Fe3O4@Carbon@MnO237. Given the positive properties mentioned for magnetite NPs coated with silica or carbon, the development of effective synthetic methods for the production of core–shell NPs containing magnetite core and both carbon and silica shells will be very valuable29.

On the other hand, the Knoevenagel reaction is one of the most important processes for the formation of carbon–carbon double bonds in synthetic organic chemistry and allows the production of low-electron olefins. Generally, Knoevenagel reactions are performed by the condensation of carbonyl compounds with active methylene. In recent years, many homogeneous and heterogeneous catalysts have been introduced to perform this reaction, that heterogeneous catalysts have received much attention due to their recoverability, reusability, structural deterioration resistance and easy separation of the products38,39,40,41,42,43,44. Some of the recently developed heterogeneous catalysts for this reaction are MS/Ag2CO345, LDH-ILs-C1246, CoFe2O447, MgO/ZrO248 and Fe3O4@OS-NH249.

Guanidines are important categoris of organic compound. In the synthetic organic chemistry, including the Knoevenagel reaction, guanidines have been shown to act as organic bases and nucleophilic catalysts. But, the main problem of catalysts based on guanidines is their separation from the product, which needs solid liquid or liquid–liquid techniques in many reactions. Therefore, supported guanidine catalysts have been more investigated. Supported guanidine catalysts are prepared via the physical or chemical immobilization of guanidines on various supports such as alumina, magnetic NPs, metal oxides, carbon nanotubes and silica50,51,52,53,54,55. In the continuance of the above studies and considering the importance of mSiO2 and carbon-coated magnetite NPs in the catalysis process, our motive in this study is the design and synthesis of a novel core@ double-shell structured Fe3O4@C@MCM-41 nanocomposite. In this reaserch, the guanidine was selected as an important organic group for functionalization of our designed nanocomposite due to it is a strong base for a variety of base-catalyzed organic reactions as well as its easy chemical immobilization on Fe3O4@C@MCM-41. The Fe3O4@C@MCM41-guanidine catalyst showed high performance to prepare of Knoevenagel derivatives in the solvent free conditions with highest yield (91–98%) in the shortest time at room temperature. Also, the Fe3O4@C@MCM41-guanidine can recovered and reused at least 10 times without the significant loss in its activity and productivity.

All chemicals were purchased from Sigma-Aldrich Chemical Co. (St. Louis, Missouri, USA), Merck Chemical Co. (Darmstadt, Germany) and Fluka Chemical Co. (Buchs, Switzerland). Cetyltrimethylammonium bromide (99%), Tetraethyl orthosilicate (≥ 99%), 3-chloropropyltrimethoxysilane (≥ 97%), Resorcinol (≥ 99%), Formaldehyde solution (37 wt. %), Toluene dried (≥ 99.5%), Guanidinium chloride (≥ 99%), Triethylamine (≥ 99.5%) and Ethyl cyanoacetate (≥ 98%) were purchased from SigmaAldrich and used without further purification. Benzaldehydes (97–99%) and NH3 (28–30% wt) were purchased from Merck. Ethanol (≥ 99.8%) was purchased from Fluka. FT-IR spectra were recorded in the range of 400–4000 cm−1 on Alpha Centaur FT-IR spectrophotometer using KBr pellets. The morphology of the synthesized NPs was investigated by using the EM3200 scanning electron microscopy (SEM) device. Transmission electron microscopy (TEM) image was recorded using a FEI TECNAI 12 BioTWIN microscope. TGA analysis was performed by a Netzsch STA 409 PC/PG apparatus in the temperature range of 25–900 °C. Powder X-ray diffraction (PXRD) analysis were carried out using D8 ADVANCE XRD and Philips XPert Pro XRD equipment, respectively. X-ray distribution analysis (EDS) was performed by the means of an EDS Sirius SD device. The magnetic effect of the synthesized NPs was investigated using vibrating sample magnetometer (VSM) of Meghnatis Daghigh Kavir Co. The uniform dispersion of the reactants was obtained using a KMM1-120WE301ultrasonication device. The TLC-Grade-silica gel-G/UV 254 Thin-layer chromatography (TLC) device was used to evaluate the reaction advancement and determine the reaction completion. The melting point was measured using a Barnstead Electro-Thermal device.

The magnetic Fe3O4 NPs were firstly prepared according to reported procedures10,56. To prepare the Fe3O4@RF NPs, 0.7 g of Fe3O4 NPs were added to the reaction vessel containing 200 mL of water and 100 mL of ethanol. Then the resulted mixture was placed in to the ultrasonic bath for 30 min at room temperature. In the following, 1.5 mL of NH3 (28–30% wt) was added in the reaction vessel at room temperature and obtained mixture was again placed in the ultrasonic bath for 15 min. After that, 1 g of resorcinol and 0.1 mL of formaldehyde solution were added in the reaction vessel, and the resulting mixture was stirred at room temperature for 24 h. Then, the resulting precipitate was separated by using a magnetic field, washed several times with water and ethanol, dried at 60 °C for 6 h and was named Fe3O4@RF57.

To preparation of Fe3O4@C@MCM41, first 0.6 g of Fe3O4@RF NPs were firstly added into the reaction vessel containing 60 mL of distilled water and was placed into the ultrasonic bath at 40 °C for 30 min. Subsequently, 3 mL of NH3 (28–30% wt) and 1 g of cetyltrimethylammonium bromide (CTAB) were added into the reaction vessel. Then, 0.7 mL of Tetraethyl orthosilicate (TEOS) was added dropwise, and the resulting mixture was stirred for 2 h. In the next step, the reaction mixture was stirred for 48 h at a temperature of 100 °C. After the end of the reaction, the obtained precipitate was separated by a magnetic field and dried. The acquired material was poured into a crucible and placed in a furnace with a temperature of 350 °C for 5 h for the remove of CTAB surfactant. Finally, the resulting material was poured into a crucible, carbonized at 600 °C for 6 h under argon atmosphere and named Fe3O4@C@MCM4158.

To immobilize 3-chloropropyltrimethoxysilane on the surface of Fe3O4@C@MCM41 NPs, 0.2 g of Fe3O4@C@MCM-41 was added into the flask reaction containing 26 mL of dry toluene and dispersed under ultrasonic waves. After that, 0.1 mL of 3-chloropropyltrimethoxysilane was added into the reaction mixture and refluxed for 24 h under argon. Then, the product was collected using a magnetic field, washed with 20 mL of toluene and 30 mL of ethanol and dried at 60 °C for 12 h.

For this, 0.2 g of Fe3O4@C@MCM-41/Pr-Cl was added into a flask reaction containing 20 mL of dry toluene under ultrasonic waves. Subsequently, 0.08 g of guanidinium chloride and 0.003 of Triethylamine were added into the flask, and the obtained mixture was refluxed condition for 28 h. After, the acquired precipitate was separated by using a magnetic field, washed with 20 mL of ethanol and dried at 50 °C for 8 h. and named Fe3O4@C@MCM-41-guanidine (Fig. 1).

Illustration for the Synthetic Methodology of Fe3O4@C@MCM41-guanidine.

For this purpose, 1 mmol of Ethyl cyanoacetate, 1 mmol of Benzaldehyde derivatives, and 1.5 mol % of Fe3O4@C@MCM-41-guanidine catalyst were added into the round-bottom flask and reaction vessel placed into ultrasonic bath at room temperature under solvent free condition. The reaction progress was monitored by TLC. After finishing of the reaction, hot ethanol was added to the reaction mixture and the catalyst was separated by an external magnet. After, the remaining solution was placed into an ice and precipitate formed. The product was separated by a paper filter and dried under ambient temperature.

Initially, the magnetic Fe3O4 NPs were synthesized. In the next step, these NPs were covered using Resorcinol–Formaldehyde (RF) polymer layer. Then, the Fe3O4@RF was covered with the MCM-41 shell by using the Sol–gel method in the presence of CTAB surfactant under alkaline conditions. After calcination to remove CTAB and carbonization, the Fe3O4@C@MCM41 was treated with 3-chloropropyltrimethoxysilane and Guanidine (Fe3O4@C@MCM41-guanidine) (Fig. 1). The Fe3O4@C@MCM41-guanidine nanocatalysts was characterized using various techniques, namely, FT-IR, PXRD, SEM, EDX, TGA and VSM.

The FT-IR spectroscopy at different stages in the synthesis of Fe3O4@C@MCM41-guanidine has been illustrated in Fig. 2. The appeared peak at 588 cm−1 is related to the vibration of the Fe–O bonds. The sharp peaks at 823 and 1027 cm−1 corresponded to the symmetric and asymmetric vibrations of Si–O–Si bonds of MCM-41 shell (Fig. 2c–e). The appeared peaks in the regions of 1417 and 1623 cm−1 are attributed to the stretch vibrations of C=C and Resorcinol–Formaldehyde (RF) polymer layer, respectively (Fig. 2b,c). The stretch vibrations of C-H Aliphatic which are attributed to the Propyl group have appeared in 2923 cm−1 (Fig. 2d,e). The wide appeared peak in the range of 3400–3500 cm−1 is related to the stretch connections of O–H and NH. The presence of these peaks verifies the successful consolidation and high stability of the expected functional groups during the stages of catalyst synthesis (Fig. 2).

FT-IR spectra of, (a) Fe3O4, (b) Fe3O4 @RF, (c) Fe3O4@C@MCM41, (d) Fe3O4@C@MCM41/Pr-Cl, (e) Fe3O4@C@MCM41-guanidine.

The wide-angle X-ray diffraction (WXRD) analysis of Fe3O4, carbon and Fe3O4@C@MCM41-guanidine nanomaterials was showed in Fig. 3. The WXRD analysis of Fe3O4 and Fe3O4@C@MCM41-guanidine demonstrated the same pattern with six sharp peaks at 2θ: 30, 35, 43, 53, 57 and 63 degrees corresponding to Miller indices of 220, 311, 400, 422, 511 and 440, respectively, proving that the Fe3O4 crystalline structure is preserved during the modification processes (Fig. 3b,c)59,60. Also, Comparison of Fig. 3a,c proved that the broad peak appearing in Fig. 3c at 2θ≈ 22 degree are related to carbon confirming the formation of carbon shell around the Fe3O4 core61,62,63.

WXRD pattern of (a) Carbon, (b) Fe3O4 and (c) Fe3O4@C@MCM41-guanidine.

The low-angle X-ray diffraction (LXRD) analysis of MCM-41 and Fe3O4@C@MCM41-guanidine was showed in Fig. 4. As seen in Fig. 4a, the pattern of MCM-41 shows a strong and sharp diffraction peak at 2θ = 2.3 degree and two low-intensity peaks at 2θ = 4.1 and 4.8 degree that these are demonstrated the hexagonal symmetry of mesoporous MCM-41. After modification of Fe3O4@C with MCM-41 and functionalization with guanidine, the same LXRD pattern is observed (Fig. 4b). This result confirms the successful coating of the Fe3O4@C with guanidine modified MCM-41 shell without causing any damage in its mesoporous structure21,64.

LXRD pattern of (a) MCM-41 and (b) Fe3O4@C@MCM41-guanidine.

The EDS spectrum showed that the Fe3O4@C@MCM41-guanidine nanocatalyst is composed of Iron, Silicon, Oxygen, Carbon, and Nitrogen elements confirming the successful incorporation/immobilization of expected species in the material framework (Fig. 5).

EDS spectrum of the Fe3O4@C@MCM41-guanidine.

The Scanning electron microscopy (SEM) technique was used for determine the appearance and particle size of the Fe3O4@C@MCM41-guanidine nanocatalyst. This analysis confirms that the designed nanocatalyst has homogeneous and nearly spherical structure. Moreover, SEM image show that the particles of this nanocatalyst are between 33–93 nm in size (Fig. 6).

SEM image of the Fe3O4@C@MCM41-guanidine.

Transmission electron microscopy (TEM) analysis was employed to validate the appearance and shell-core structure of the Fe3O4@C@MCM41-guanidine nanocatalyst. The TEM image showed that the designed nanocatalyst has a core–shell structure with a black core (magnetite particles) and gray shells (Fig. 7).

TEM image of the Fe3O4@C@MCM41-guanidine.

The thermal stability of the Fe3O4@C@MCM41-guanidine catalyst was investigated using thermal gravimetric analysis. This analysis was performed in the temperature range of 25 to 900 °C. The weight loss in the first stage (up to 100 °C) indicates the extraction of water and existing organic solvents in the synthesis stages of the catalyst. In the second stage, the weight loss in the temperature range of 100 to 300 °C indicates the extraction of residual surfactant. The weight loss in the next stage which occurs in the temperature range of 300 to 480 °C shows the elimination of organic groups. In the last stage, the weight loss at the temperature range of 400 to 800 °C shows the extraction of the remaining organic groups. This analysis shows the presence and thermal stability of the groups that covered the surface of the Fe3O4 magnetic NPs (Fig. 8).

Thermal gravimetric analysis of Fe3O4@C@MCM41-guanidine.

The magnetic properties of Fe3O4 and Fe3O4@C@MCM41-guanidine nanomaterials were investigated by vibrating sample magnetometer (VSM) analysis. The results of this analysis showed that Fe3O4 and Fe3O4@C@MCM41-guanidine have a superparamagnetic behavior. The magnetic saturation of Fe3O4 and Fe3O4@C@MCM41-guanidine nanomaterials were 60 and 47 emu/g, respectively. The decrease in saturation magnetization confirms successful chemical immobilization of Carbon, MCM41 and guanidine moieties on the surface of the Fe3O4 NPs (Fig. 9). Also, this proves the high magnetic properties of Fe3O4 and Fe3O4@C@MCM41-guanidine nanomaterials, which are very important for their easy separation in the chemical processes.

Vibrating sample magnetometry analysis of (a) Fe3O4 (b) Fe3O4@C@MCM41-guanidine.

After the synthesis of Fe3O4@C@MCM41-guanidine nanostructure, its catalytic activity was investigated in the Knoevenagel reaction. For this purpose, the reaction conditions were firstly optimized. To optimize the reaction condition, the condensation between benzaldehyde and ethyl cyanoaceteat was selected as the model reaction. The effects of temperature, catalyst loading, and solvent were investigated under ultrasonic conditions. Examination of different solvents showed that the reaction yield was very low in the presence solvents such as toluene and acetonitrile, and it was slightly better in polar solvents such as ethanol and water. The best result was obtained under the solvent-free conditions. Subsequently, the catalyst loading was optimized with 0.5, 1.5, and 2.5 mol% of catalyst. The best yield was obtained with 1.5 mol%. It should be noted that the increase of catalyst loading did not affect the reaction progress because the amount of raw materials corresponds to 1.5% of catalyst and the excess amount of catalyst will be practically useless. The catalytic effect of Fe3O4@C@MCM41-guanidine can be proved by noting that the catalyst-free reaction did not make much progress after a long time (Table 1).

From the reaction of different aldehydes in the presence of 1.5 mol% of Fe3O4@C@MCM41-guanidine nanocatalyst in solvent-free conditions and at room temperature under ultrasonic waves, ethyl 2-Cyano-3-phenyl acrylate products were obtained with high yields. As shown in Table 2, aldehydes with electron acceptors groups such as 4-nitro benzaldehyde (Table 2, entry 7), 4-chloro-benzaldehyde (Table 2, entry 2), 4-cyano-benzaldehyde (Table 2, entry 8), have very good performance and have high efficiency in a short time. Also, electron donor aldehydes such as 4-methoxy benzaldehyde (Table 2, entry 4), and 3-ethoxy-4-hydroxybenzaldehyde (Table 2, entry 6) have moderate and good performance and efficiency under this conditions. Moreover, aldehydes with space barriers such as 2-hydroxy (Table 2, entry 5) and 2-methyl (Table 2, entry 3) have relatively good efficiencies, indicating the high performance of Fe3O4@C@MCM41-guanidine nanocatalysts in the Knoevenagel reaction (Table 2). It should be noted that according to previous studies, condensation between condensations of cyanoacetate with aromatic and aliphatic aldehydes leads to the formation of a product with E-isomer45.

To investigate the recyclability and reusability of Fe3O4@C@MCM41-guanidine nanocatalyst in the Knoevenagel reaction, 1 mmol of benzaldehyde, 1 mmol of Ethyl cyanoacetate, and 1.5 mol% of Fe3O4@C@MCM41-guanidine nanocatalyst at room temperature were selected as model reaction under solvent-free condition and ultrasound waves. Upon completion of the process, the magnetic nanocatalyst was separated using an external magnet, washed completely with ethanol, and dried. Then the recovered catalyst was reused in the next reaction cycle under the same conditions as the first run. The results show that the catalyst can be reused at least 10 times without significantly reducing the reaction time and efficiency (Fig. 10).

Recoverability and reusability results of Fe3O4@C@MCM41-guanidine nanocatalyst.

In the mechanism of the Knoevenagel reaction, one of the active hydrogens of methylene is separated by a base. Then, a nucleophilic attack is performed on carbon aldehyde or ketones. As can be observed in the Fig. 11, the base catalyst separates the active methylene hydrogen from ethyl cyanoacetate. The corresponding enolate is formed with the role of a nucleophile, then the resulting enolate leads to the formation of the corresponding β-hydroxyl with simultaneous nucleophile attack to carbonyl and attracting protons from the catalyst. In the next step, the desired product is formed by removing the water.

Proposed mechanism of Fe3O4@C@MCM41-guanidine in the Knoevenagel reaction.

In summary, in this study, Fe3O4@C@MCM41-guanidine nanocatalyst was successfully prepared and its catalytic performance was studied. FT-IR, EDX and TGA are shown successful stabilization of the guanidine groups on the surface of the Fe3O4@C@MCM41 nanostructure. SEM and TEM analysis confirms the spherical structure of the Fe3O4@C@MCM41-guanidine nanostructure. The WXRD proved the high stability of crystalline structure of Fe3O4 NPs during the material preparation. The LXRD also confirmed the formation of mesoporous silica shell around Fe3O4@C NPs. The VSM analysis demonstrated good magnetic properties of this nanocomposite. The catalyst showed excellent activity in the Knoevenagel reaction. Catalyst was simply recycled and reused 10 times without significant reduction in activity.

All data and materials are included in the manuscript.

Kwizera, E. A. et al. Size-and shape-controlled synthesis and properties of magnetic–plasmonic core–shell nanoparticles. J. Phys. Chem. C 120, 10530–10546 (2016).

Article CAS Google Scholar

Khatami, M., Alijani, H. Q., Nejad, M. S. & Varma, R. S. Core@ shell nanoparticles: Greener synthesis using natural plant products. Appl. Sci. 8, 411 (2018).

Article Google Scholar

Shaker, M. & Elhamifar, D. Pd-containing IL-based ordered nanostructured organosilica: A powerful and recoverable catalyst for Sonogashira reaction. Tetrahedron Lett. 61, 152481 (2020).

Article CAS Google Scholar

Wang, J., Shah, Z. H., Zhang, S. & Lu, R. Silica-based nanocomposites via reverse microemulsions: classifications, preparations, and applications. Nanoscale 6, 4418–4437 (2014).

Article ADS CAS PubMed Google Scholar

Han, Y., Jiang, J., Lee, S. S. & Ying, J. Y. Reverse microemulsion-mediated synthesis of silica-coated gold and silver nanoparticles. Langmuir 24, 5842–5848 (2008).

Article CAS PubMed Google Scholar

Chatterjee, K., Sarkar, S., Rao, K. J. & Paria, S. Core/shell nanoparticles in biomedical applications. Adv. Colloid Interface Sci. 209, 8–39 (2014).

Article CAS PubMed Google Scholar

Dash, A., Blasiak, B., Tomanek, B., Latta, P. & van Veggel, F. C. Target-specific magnetic resonance imaging of human prostate adenocarcinoma using NaDyF4–NaGdF4 core-shell nanoparticles. ACS Appl. Mater. Interfaces 1, 1 (2021).

Google Scholar

Lee, N. et al. Multifunctional Fe3O4/TaO x Core/Shell nanoparticles for simultaneous magnetic resonance imaging and X-ray computed tomography. J. Am. Chem. Soc. 134, 10309–10312 (2012).

Article CAS PubMed Google Scholar

Li, M. et al. Au@ MnS@ ZnS core/shell/shell nanoparticles for magnetic resonance imaging and enhanced cancer radiation therapy. ACS Appl. Mater. Interfaces 8, 9557–9564 (2016).

Article ADS CAS PubMed Google Scholar

Barzkar, A. & Beni, A. S. In situ synthesis of SO 3 H supported Fe 3 O 4@ resorcinol–formaldehyde resin core/shell and its catalytic evaluation towards the synthesis of hexahydroquinoline derivatives in green conditions. RSC Adv. 10, 41703–41712 (2020).

Article ADS CAS PubMed PubMed Central Google Scholar

Liu, Y. et al. Self-driven microstructural evolution of Au@ Pd core–shell nanoparticles for greatly enhanced catalytic performance during methanol electrooxidation. Nanoscale 13, 3528–3542 (2021).

Article CAS PubMed Google Scholar

Rajabi-Moghaddam, H., Naimi-Jamal, M. & Tajbakhsh, M. Fabrication of copper (II)-coated magnetic core-shell nanoparticles Fe 3 O 4@ SiO 2-2-aminobenzohydrazide and investigation of its catalytic application in the synthesis of 1, 2, 3-triazole compounds. Sci. Rep. 11, 1–14 (2021).

Article Google Scholar

Mahdavi, Z., Rezvani, H. & Moraveji, M. K. Core–shell nanoparticles used in drug delivery-microfluidics: A review. RSC Adv. 10, 18280–18295 (2020).

Article ADS PubMed PubMed Central Google Scholar

Lai, C.-C. et al. A solar-thermal energy harvesting scheme: enhanced heat capacity of molten HITEC salt mixed with Sn/SiO x core–shell nanoparticles. Nanoscale 6, 4555–4559 (2014).

Article ADS CAS PubMed Google Scholar

Han, J. et al. Origin of enhanced piezoelectric energy harvesting in all-polymer-based core–shell nanofibers with controlled shell-thickness. Compos. B. Eng. 223, 109141 (2021).

Article CAS Google Scholar

Sun, Y. et al. Complete Au@ ZnO core–shell nanoparticles with enhanced plasmonic absorption enabling significantly improved photocatalysis. Nanoscale 8, 10774–10782 (2016).

Article ADS CAS PubMed Google Scholar

Meng, X., Fujita, K., Moriguchi, Y., Zong, Y. & Tanaka, K. Metal–dielectric core–shell nanoparticles: advanced plasmonic architectures towards multiple control of random lasers. Adv. Opt. Mater. 1, 573–580 (2013).

Article Google Scholar

Majhi, S. M., Rai, P. & Yu, Y.-T. Facile approach to synthesize Au@ ZnO core–shell nanoparticles and their application for highly sensitive and selective gas sensors. ACS Appl. Mater. Interfaces 7, 9462–9468 (2015).

Article CAS PubMed Google Scholar

Zheng, S. et al. Lanthanide-doped NaGdF 4 core–shell nanoparticles for non-contact self-referencing temperature sensors. Nanoscale 6, 5675–5679 (2014).

Article ADS CAS PubMed Google Scholar

Majhi, S. M. et al. Au@ NiO core-shell nanoparticles as a p-type gas sensor: Novel synthesis, characterization, and their gas sensing properties with sensing mechanism. Sens. Actuators B Chem. 268, 223–231 (2018).

Article CAS Google Scholar

Shaker, M. & Elhamifar, D. Cu-containing magnetic yolk-shell structured ionic liquid-based organosilica nanocomposite: A powerful catalyst with improved activity. Compos. Commun. 24, 100608 (2021).

Article Google Scholar

Mirbagheri, R., Elhamifar, D. & Shaker, M. Yolk–shell structured magnetic mesoporous silica: a novel and highly efficient adsorbent for removal of methylene blue. Sci. Rep. 11, 1–15 (2021).

Article Google Scholar

Mofatehnia, P., Ziarani, G. M., Elhamifar, D. & Badiei, A. A new yolk-shell hollow mesoporous nanocomposite, Fe3O4@ SiO2@ MCM41-IL/WO42-, as a catalyst in the synthesis of novel pyrazole coumarin compounds. J. Phys. Chem. Solids 155, 110097 (2021).

Article CAS Google Scholar

Tian, H., Liu, F. & He, J. Multifunctional Fe3O4@ nSiO2@ mSiO2–Fe core–shell microspheres for highly efficient removal of 1, 1, 1-trichloro-2, 2-bis (4-chlorophenyl) ethane (DDT) from aqueous media. J. Colloid Interface Sci. 431, 90–96 (2014).

Article ADS CAS PubMed Google Scholar

Haydari, Z., Elhamifar, D., Shaker, M. & Norouzi, M. Magnetic nanoporous MCM-41 supported melamine: A powerful nanocatalyst for synthesis of biologically active 2-amino-3-cyanopyridines. Appl. Surf. Sci. Adv. 5, 100096 (2021).

Article Google Scholar

Ma, J., Sun, N., Wang, C., Xue, J. & Qiang, L. Facile synthesis of novel Fe3O4@ SiO2@ mSiO2@ TiO2 core-shell microspheres with mesoporous structure and their photocatalytic performance. J. Alloys Compd. 743, 456–463 (2018).

Article CAS Google Scholar

Li, W. et al. Synthesis of rattle-type magnetic mesoporous Fe 3 O 4@ mSiO 2@ BiOBr hierarchical photocatalyst and investigation of its photoactivity in the degradation of methylene blue. RSC Adv. 5, 48050–48059 (2015).

Article ADS CAS Google Scholar

Li, F. et al. Removal and recovery of phosphate and fluoride from water with reusable mesoporous Fe3O4@ mSiO2@ mLDH composites as sorbents. J. Hazard. Mater. 388, 121734 (2020).

Article CAS PubMed Google Scholar

Yang, T., Liu, J., Zheng, Y., Monteiro, M. J. & Qiao, S. Z. Facile fabrication of core–shell-structured Ag@ carbon and mesoporous Yolk–Shell-structured Ag@ carbon@ silica by an extended Stöber method. Chem. Eur. J. 19, 6942–6945 (2013).

Article CAS PubMed Google Scholar

Zhou, Z. & Liu, R. Fe3O4@ polydopamine and derived Fe3O4@ carbon core–shell nanoparticles: comparison in adsorption for cationic and anionic dyes. Colloids Surf. A Physicochem. Eng. Asp. 522, 260–265 (2017).

Article CAS Google Scholar

Manna, K. & Srivastava, S. K. Fe3O4@ carbon@ polyaniline trilaminar core–shell composites as superior microwave absorber in shielding of electromagnetic pollution. ACS Sustain. Chem. Eng. 5, 10710–10721 (2017).

Article CAS Google Scholar

Han, C. et al. Biopolymer-assisted synthesis of 3D interconnected Fe3O4@ carbon core@ shell as anode for asymmetric lithium ion capacitors. Carbon 140, 296–305 (2018).

Article CAS Google Scholar

Zarnegaryan, A. & Beni, A. S. Immobilization of hexamolybdate onto carbon-coated Fe3O4 nanoparticle: A novel catalyst with high activity for oxidation of alcohols. J. Organomet. Chem. 953, 122043 (2021).

Article CAS Google Scholar

Abaeezadeh, S., Beni, A. S., Zarnegaryan, A. & Nabavizadeh, M. Immobilization of polyoxometalate onto modified magnetic nanoparticles: A new catalyst for the synthesis of dihydropyranopyrazole derivatives. ChemistrySelect 6, 11039–11046 (2021).

Article CAS Google Scholar

Yuan, G. et al. Rational design of dumbbell-like Au-Fe3O4@ Carbon yolk@ shell nanospheres with superior catalytic activity. Colloids Surf. A Physicochem. Eng. Asp. 623, 126665 (2021).

Article CAS Google Scholar

Zhang, X., Zhu, S., Deng, C. & Zhang, X. Highly sensitive thrombin detection by matrix assisted laser desorption ionization-time of flight mass spectrometry with aptamer functionalized core–shell Fe3O4@ C@ Au magnetic microspheres. Talanta 88, 295–302 (2012).

Article CAS PubMed Google Scholar

Chen, X. et al. Hierarchical Fe3O4@ carbon@ MnO2 hybrid for electromagnetic wave absorber. J. Colloid Interface Sci. 553, 465–474 (2019).

Article ADS CAS PubMed Google Scholar

Appaturi, J. N. et al. A review of the recent progress on heterogeneous catalysts for Knoevenagel condensation. Dalton Trans. 50, 4445–4469 (2021).

Article CAS PubMed Google Scholar

Trotzki, R., Hoffmann, M. M. & Ondruschka, B. Studies on the solvent-free and waste-free Knoevenagel condensation. Green Chem. 10, 767–772 (2008).

Article CAS Google Scholar

Zengin, N., Burhan, H., Şavk, A., Göksu, H. & Şen, F. Synthesis of benzylidenemalononitrile by Knoevenagel condensation through monodisperse carbon nanotube-based NiCu nanohybrids. Sci. Rep. 10, 1–7 (2020).

Article Google Scholar

Choudhary, P. et al. Sulfonic acid functionalized graphitic carbon nitride as solid acid–base bifunctional catalyst for Knoevenagel condensation and multicomponent tandem reactions. Mater. Chem. Front. 5, 6265–6278 (2021).

Article CAS Google Scholar

Bahuguna, A., Kumar, A., Chhabra, T., Kumar, A. & Krishnan, V. Potassium-functionalized graphitic carbon nitride supported on reduced graphene oxide as a sustainable catalyst for Knoevenagel condensation. ACS Appl. Nano Mater. 1, 6711–6723 (2018).

Article CAS Google Scholar

del Hierro, I., Perez, Y. & Fajardo, M. Supported choline hydroxide (ionic liquid) on mesoporous silica as heterogeneous catalyst for Knoevenagel condensation reactions. Microporous Mesoporous Mater. 263, 173–180 (2018).

Article CAS Google Scholar

Guo, F. A mononuclear Cu (II)-based metal-organic framework as an efficient heterogeneous catalyst for chemical transformation of CO2 and Knoevenagel condensation reaction. Inorg. Chem. Commun. 101, 87–92 (2019).

Article CAS Google Scholar

Karimkhah, F., Elhamifar, D. & Shaker, M. Ag2CO3 containing magnetic nanocomposite as a powerful and recoverable catalyst for Knoevenagel condensation. Sci. Rep. 11, 18736 (2021).

Article ADS CAS PubMed PubMed Central Google Scholar

Li, T., Zhang, W., Chen, W., Miras, H. N. & Song, Y.-F. Layered double hydroxide anchored ionic liquids as amphiphilic heterogeneous catalysts for the Knoevenagel condensation reaction. Dalton Trans. 47, 3059–3067 (2018).

Article CAS PubMed Google Scholar

Senapati, K. K., Borgohain, C. & Phukan, P. Synthesis of highly stable CoFe2O4 nanoparticles and their use as magnetically separable catalyst for Knoevenagel reaction in aqueous medium. J. Mol. Catal. A 339, 24–31 (2011).

Article CAS Google Scholar

Gawande, M. B. & Jayaram, R. V. A novel catalyst for the Knoevenagel condensation of aldehydes with malononitrile and ethyl cyanoacetate under solvent free conditions. Catal. Commun. 7, 931–935 (2006).

Article CAS Google Scholar

Mirbagheri, R., Elhamifar, D. & Norouzi, M. Propylamine-containing magnetic ethyl-based organosilica with a core–shell structure: An efficient and highly stable nanocatalyst. New J. Chem. 42, 10741–10750 (2018).

Article CAS Google Scholar

Maleki, R., Koukabi, N. & Kolvari, E. Fe3O4-Methylene diphenyl diisocyanate-guanidine (Fe3O4–4, 4′-MDI-Gn): A novel superparamagnetic powerful basic and recyclable nanocatalyst as an efficient heterogeneous catalyst for the Knoevenagel condensation and tandem Knoevenagel-Michael-cyclocondensation reactions. Appl. Organomet. Chem. 32, e3905 (2018).

Article Google Scholar

Han, J., Xu, Y., Su, Y., She, X. & Pan, X. Guanidine-catalyzed Henry reaction and Knoevenagel condensation. Catal. Commun. 9, 2077–2079 (2008).

Article CAS Google Scholar

Atashkar, B., Rostami, A. & Tahmasbi, B. Magnetic nanoparticle-supported guanidine as a highly recyclable and efficient nanocatalyst for the cyanosilylation of carbonyl compounds. Catal. Sci. Technol. 3, 2140–2146 (2013).

Article CAS Google Scholar

Jafari, F., Ghorbani-Choghamarani, A. & Hasanzadeh, N. Guanidine complex of copper supported on boehmite nanoparticles as practical, recyclable, chemo and homoselective organic–inorganic hybrid nanocatalyst for organic reactions. Appl. Organomet. Chem. 34, e5901 (2020).

Article CAS Google Scholar

Peng, W. et al. Guanidine-functionalized amphiphilic silica nanoparticles as a pickering interfacial catalyst for biodiesel production. Ind. Eng. Chem. Res. 59, 4273–4280 (2020).

Article CAS Google Scholar

Blanc, A. C. et al. The preparation and use of novel immobilised guanidine catalysts in base-catalysed epoxidation and condensation reactions. Green Chem. 2, 283–288 (2000).

Article CAS Google Scholar

Veisi, H., Taheri, S. & Hemmati, S. Preparation of polydopamine sulfamic acid-functionalized magnetic Fe 3 O 4 nanoparticles with a core/shell nanostructure as heterogeneous and recyclable nanocatalysts for the acetylation of alcohols, phenols, amines and thiols under solvent-free conditions. Green Chem. 18, 6337–6348 (2016).

Article CAS Google Scholar

Wu, N. et al. Enhanced electromagnetic wave absorption of three-dimensional porous Fe3O4/C composite flowers. ACS Sustain. Chem. Eng. 6, 12471–12480 (2018).

Article CAS Google Scholar

Zhu, Y., Kockrick, E., Ikoma, T., Hanagata, N. & Kaskel, S. An efficient route to rattle-type Fe3O4@ SiO2 hollow mesoporous spheres using colloidal carbon spheres templates. Chem. Mater. 21, 2547–2553 (2009).

Article CAS Google Scholar

Xie, X., Chen, L., Pan, X. & Wang, S. Synthesis of magnetic molecularly imprinted polymers by reversible addition fragmentation chain transfer strategy and its application in the Sudan dyes residue analysis. J. Chromatogr. A 1405, 32–39 (2015).

Article CAS PubMed Google Scholar

Zhong, Y., Ni, Y., Li, S. & Wang, M. Chain-like Fe 3 O 4@ resorcinol-formaldehyde resins–ag composite microstructures: Facile construction and applications in antibacterial and catalytic fields. RSC Adv. 6, 15831–15837 (2016).

Article ADS CAS Google Scholar

Sun, M. et al. Fe3O4 nanoparticles on 3D porous carbon skeleton derived from rape pollen for high-performance Li–Ion capacitors. Nanomaterials 11, 3355 (2021).

Article CAS PubMed PubMed Central Google Scholar

Xiang, H. et al. Fe3O4@ C nanoparticles synthesized by in situ solid-phase method for removal of methylene blue. Nanomaterials 11, 330 (2021).

Article CAS PubMed PubMed Central Google Scholar

Liu, J. et al. Facile preparation of Fe3O4/C nanocomposite and its application for cost-effective and sensitive detection of tryptophan. Biomolecules 9, 245 (2019).

Article CAS PubMed PubMed Central Google Scholar

Mousavi, F., Elhamifar, D. & Kargar, S. Copper/IL-containing magnetic nanoporous MCM-41: A powerful and highly stable nanocatalyst. Surf. Interfaces 25, 101225 (2021).

Article CAS Google Scholar

Wang, S.-X., Li, J.-T., Yang, W.-Z. & Li, T.-S. Synthesis of ethyl α-cyanocinnamates catalyzed by KF–Al2O3 under ultrasound irradiation. Ultrason. Sonochem. 9, 159–161 (2002).

Article PubMed Google Scholar

Elhamifar, D., Kazempoor, S. & Karimi, B. Amine-functionalized ionic liquid-based mesoporous organosilica as a highly efficient nanocatalyst for the Knoevenagel condensation. Catal. Sci. Technol. 6, 4318–4326 (2016).

Article CAS Google Scholar

Download references

The authors thank the Yasouj University for supporting this work.

Department of Chemistry, Faculty of Science, Yasouj University, Yasouj, 75918-74831, Iran

Aliyeh Barzkar & Alireza Salimi Beni

You can also search for this author in PubMed Google Scholar

You can also search for this author in PubMed Google Scholar

A.B.: Writing—Original Draft, Investigation, Resources, Formal analysis. A.S.B.: Conceptualization, Writing—Review & Editing, Supervision, Visualization.

Correspondence to Alireza Salimi Beni.

The authors declare no competing interests.

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.

Reprints and Permissions

Barzkar, A., Beni, A.S. Fe3O4@C@MCM41-guanidine core–shell nanostructures as a powerful and recyclable nanocatalyst with high performance for synthesis of Knoevenagel reaction. Sci Rep 13, 10336 (2023). https://doi.org/10.1038/s41598-023-36352-5

Download citation

Received: 16 February 2023

Accepted: 01 June 2023

Published: 26 June 2023

DOI: https://doi.org/10.1038/s41598-023-36352-5

Anyone you share the following link with will be able to read this content:

Sorry, a shareable link is not currently available for this article.

Provided by the Springer Nature SharedIt content-sharing initiative

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.