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Synthesis and characterization of the immobilized polythiophene on magnetic carbon nanotube as a prominent catalyst for the synthesis of dihydropyrimidinone and octahydroquinazolinone derivatives Parisa Akbarzadeh1 · Nadiya Koukabi1  Received: 3 May 2020 / Accepted: 5 August 2020 © Springer Nature B.V. 2020

Abstract In this work, the immobilized polythiophene on magnetic carbon nanotube (CNT– Fe3O4–PTh) was synthesized and introduced as a novel and recoverable catalytic system. The prepared magnetic heterogeneous nanocatalyst was characterized by FT-IR, TGA, EDX, VSM, XRD, TEM, and FE-SEM. Next, the catalytic efficiency of CNT–Fe3O4–PTh was evaluated through the green synthesis of a variety of dihydropyrimidinone and octahydroquinazolinone through Biginelli reaction between aromatic aldehydes, urea/thiourea, and β-dicarbonyl compounds under solvent-free conditions. The catalyst was magnetically recovered and recycled for five cycles without a discernible loss in its catalytic activity. Simple workup, affordability, short reaction times, mild reaction conditions, and the high yield of products are the interesting features of this project. Graphic abstract An environmentally benign nanocomposite was prepared using carbon nanotube as an inexpensive, nontoxic, and stable support in the preparation of CNT–Fe3O4–PTh, which was efficiently used as catalyst for the green synthesis of dihydropyrimidinone

Electronic supplementary material  The online version of this article (https​://doi.org/10.1007/s1116​ 4-020-04234​-4) contains supplementary material, which is available to authorized users. * Nadiya Koukabi [email protected] 1



Department of Chemistry, Semnan University, Semnan 35131‑19111, Iran

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P. Akbarzadeh, N. Koukabi

and octahydroquinazolinone derivatives through Biginelli reaction under solventfree conditions.

Keywords  Biginelli reaction · Carbon nanotubes · Heterogeneous catalyst · Magnetic nanoparticles · Polythiophene

Introduction In recent years, functionalized carbon nanotubes (CNTs) have been widely studied in terms of separation, properties, and catalytic activities due to their particular catalytic application compared to homogeneous complexes of CNTs. Carbon nanotubes owing to their low cost, mechanical stability, high aspect ratio, excellent thermal and electronic conductivity, tunable carbon framework, hollow and layered nanosized structures, and porous character have become of keen attention more and more for material scientists [1, 2]. As a result, the unique properties of CNTs made them the ideal candidates for numerous applications in catalysis, diagnostics, solar cells, electronics, and drug delivery [3–7]. Nevertheless, there is difficulty in the isolation of CNTs from the reaction mixture and their recovery. So, the need to design new modified CNTs is unavoidable in order to overcome the aforementioned drawback. Magnetite ­Fe3O4 nanoparticles have drawn remarkable consideration as a powerful catalyst support due to their unique characteristics including chemi