FULL PAPER Superparamagnetic Fe 3 O 4 @Alginate supported L-arginine as a powerful hybrid inorganic–organic nanocatalyst for the one-pot synthesis of pyrazole derivatives Sara Amirnejat | Aliakbar Nosrati | Shahrzad Javanshir Heterocyclic Chemistry Research Laboratory, Chemistry Department, Iran University of Science and Technology, Tehran, 16846-13114, Iran Correspondence Shahrzad Javanshir, Heterocyclic Chemistry Research Laboratory, Chemistry Department, Iran University of Science and Technology, Tehran 16846-13114, Iran. Email: shjavan@iust.ac.ir Hybrid inorganic–organic material Fe 3 O 4 @Alg@CPTMS@Arg, was prepared by the layer-by-layer techniques through grafting l-arginine (l-arg) to Fe 3 O 4 @Alg using 3-chloropropyltrimethoxysilane (CPTMS) as a linker. Fe 3 O 4 @Alg was prepared by in situ co-precipitation of iron (iii) and iron (ii) chloride in the presence alginate (Alg). The hybrid inorganic–organic mate- rial was characterized employing various techniques such as Fourier transform infrared (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and vibrating sample magnetometer (VSM). The as-prepared Fe 3 O 4 @Alg@CPTMS@Arg nanoparticles mediated the synthesis of pyrazole derivatives with via one-pot reaction between phenylhydrazine, malononitrile, and various aromatic aldehydes under reflux in ethanol. Recycled catalyst exhibited comparable efficacy after seven cycles. The high catalytic activity, excellent yields, as well as the recyclability of the hybrid nanomaterials with quantitative efficiency, are factors that render this environmentally benign procedure appealing. KEYWORDS inorganic–organic nanocatalyst, L-arginine, magnetic nanoparticles, pyrazoles, sodium alginate 1 | INTRODUCTION To promote safer and more sustainable organic synthetic protocols, considerable attention has recently been paid to methods based on the principles of green chemistry. [1] This approach consists of the utilization of eco-friendly chemicals, solvents, and catalysts with longer lifetimes, and atom efficiency processes. Inorganic–organic hybrid materials constitute a new and interesting area of research in materials science with many fields of applications. [2–5] The functionalization of inorganic mag- netic nanoparticles coated with organic polymer shells represents one of the most appropriate and current methods for manufacturing magnetic polymer/inorganic nano-hybrids with promising applications in heteroge- neous catalysis because of their ease of separation and good reusability. [6,7] It is important to underline that, today, more emphasis is placed on the development of heteroge- neous catalysts based on biopolymers. In this regard, polysaccharides which are large macromolecules avail- able from natural sources with structural diversity and biocompatibility are very attractive candidates. [8–13] As a sustainable material, these interesting natural Received: 16 April 2020 Revised: 25 May 2020 Accepted: 30 May 2020 DOI: 10.1002/aoc.5888 Appl Organomet Chem. 2020;e5888. wileyonlinelibrary.com/journal/aoc © 2020 John Wiley & Sons, Ltd. 1 of 13 https://doi.org/10.1002/aoc.5888