Guanidinylated SBA-15/Fe3O4 mesoporous nanocomposite as an efficient catalyst for the synthesis of pyranopyrazole derivatives

Fereshte Hassanzadeh-Afruzi,Sara Mehraeen,Ali Maleki,Zeinab Amiri-Khamakani,Somayeh Asgharnasl

doi:10.1038/s41598-021-99120-3

Fereshte Hassanzadeh-Afruzi, Sara Mehraeen + Show 3 more

Open Access

https://doi.org/10.1038/s41598-021-99120-3

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Journal: Scientific Reports	Publication Date: Oct 6, 2021
Citations: 32	License type: open-access

Affiliation: Iran University of Science and Technology

Abstract

In this study, a novel mesoporous nanocomposite was fabricated in several steps. In this regard, SBA-15 was prepared by the hydrothermal method, next it was magnetized by in-situ preparation of Fe3O4 MNPs. After that, the as-prepared SBA-15/Fe3O4 functionalized with 3-minopropyltriethoxysilane (APTES) via post-synthesis approach. Then, the guanidinylated SBA-15/Fe3O4 was obtained by nucleophilic addition of APTES@SBA-15/Fe3O4 to cyanimide. The prepared nanocomposite exhibited excellent catalytic activity in the synthesis of dihydropyrano[2,3-c]pyrazole derivatives which can be related to its physicochemical features such as strong basic sites (presented in guanidine group), Lewis acid site (presented in Fe3O4), high porous structure, and high surface area. The characterization of the prepared mesoporous nanocomposite was well accomplished by different techniques such as FT-IR, EDX, FESEM, TEM, VSM, TGA, XRD and BET. Furthermore, the magnetic catalyst was reused at least six consequent runs without considerable reduction in its catalytic activity.

Highlights

In this study, a novel mesoporous nanocomposite was fabricated in several steps
After the functionalization of the SBA-15/Fe3O4 with as-prepared SBA-15/Fe3O4 functionalized with 3-minopropyltriethoxysilane (APTES), two new absorption bands have emerged in 1562 and 2925 cm-1 which are related to the bending vibration of N H2 and the stretching vibrations of the C-H bond in the propyl chain of APTES, respectively in this spectrum the intensity of absorption of the Si–OH bands at 958 cm-1 was decreased, signifying that the surface silanols are substituted by aminosilane groups after functionalization[35,36]
Nucleophilic addition of APTES@SBA-15/Fe3O4 to cyanimide resulted in disappearing the bending vibration of NH2 at 1560 cm-1 and intensification the absorption band at 1627 cm-1 which can be attributed to the stretching vibrations of the imine bond of guanidine group formed during this final step modification[37]

Summary

Introduction

A novel mesoporous nanocomposite was fabricated in several steps. In this regard, SBA15 was prepared by the hydrothermal method, it was magnetized by in-situ preparation of Fe3O4 MNPs. In continuation of research on heterogeneous nanocatalysts[28,29,30], in this study a novel SBA-15 based nanocomposite prepared in four steps as illustrated, it was used as a heterogeneous catalyst in the synthesis of dihydropyrano[2,3-c]pyrazole derivatives via four component condensation reaction (Fig. 1b).

Results

Conclusion