Mesoporous halloysite nanotubes modified by CuFe2O4 spinel ferrite nanoparticles and study of its application as a novel and efficient heterogeneous catalyst in the synthesis of pyrazolopyridine derivatives

Ali Maleki,Zoleikha Hajizadeh,Peyman Salehi

doi:10.1038/s41598-019-42126-9

Abstract

In this study, mesoporous halloysite nanotubes (HNTs) were modified by CuFe2O4 nanoparticles for the first time. The morphology, porosity and chemistry of the CuFe2O4@HNTs nanocomposite were fully characterized by Fourier transform infrared (FT-IR) spectroscopy, field-emission scanning electron microscopy (FE-SEM) image, transmission electron microscope (TEM) images, energy-dispersive X-ray (EDX), X-ray diffraction (XRD) pattern, Brunauer-Emmett-Teller (BET) adsorption-desorption isotherm, thermogravimetric (TG) and vibrating sample magnetometer (VSM) curve analyses. The results confirmed that CuFe2O4 with tetragonal structure, uniform distribution, and less agglomeration was located at HNTs. CuFe2O4@HNTs nanocomposite special features were high thermal stability, crystalline structure, and respectable magnetic property. SEM and TEM results showed the nanotube structure and confirmed the stability of basic tube in the synthetic process. Also, inner diameters of tubes were increased in calcination temperature at 500 °C. A good magnetic property of CuFe2O4@HNTs led to use it as a heterogeneous catalyst in the synthesis of pyrazolopyridine derivatives. High efficiency, green media, mild reaction conditions and easily recovery of the nanocatalyst are some advantages of this protocol.

Highlights

Efforts to achieve the benefits of both heterogeneous and homogeneous catalysts, caused suggestion of magnetic nanoparticles (MNPs) by scientists[1]
The properties of this novel and retrievable magnetic nanocomposite such as nanotube morphology, thermal stability, porosity, magnetic properties were examined by different analyses like Fourier transform infrared (FT-IR), field-emission scanning electron microscopy (FE-SEM), transmission electron microscope (TEM), BET, energy-dispersive X-ray (EDX), X-ray diffraction (XRD), Thermogravimetric analysis (TGA) and vibrating sample magnetometer (VSM)
The catalytic performance of CuFe2O4@halloysite nanotubes (HNTs) was checked in the synthesis of pyrazolopyridines

Summary

Results and Discussion

CuFe2O4@HNTs as a mesoporous nanocomposite was synthesized by a simple method using eco-friendly materials. EDX was applied to identify the elements of CuFe2O4@HNTs nanocomposite. As displayed by VSM analysis (Fig. 3b), the saturation magnetization values of CuFe2O4@HNTs nanocomposite was around 30 emu g−1. The loading of CuFe2O4 NPs on HNTs causes the saturation magnetization level to decrease and confirms the synthesis of the nanocomposite. This magnetic property is acceptable and nanocomposite can be separated from the reaction mixture. A mixture of hydrazine hydrate 1 (2 mmol), ethyl acetoacetate 2 (2 mmol), aromatic aldehydes 3 (1 mmol), and ammonium acetate 4 (3 mmol), in the presence of CuFe2O4@HNTs nanocatalyst (5 mg) was reacted in ethanol at room temperature.

Conclusions

Author Contributions

Additional Information