Neodymium magnetic field meets nanocatalysis: a sustainable route to novel azines and condensed heterocycles

www.nature.com/scientificreports OPEN Neodymium magnetic field meets nanocatalysis: a sustainable route to novel azines and condensed heterocycles H. A. Morsy1, Ahmed H. Moustafa2, Hassan A. El-Sayed Doaa A. Elsayed 2 2, Mohamed G. Assy2 & A sustainable and effective approach for manufacturing heterocyclic compounds was established utilizing Fe₃O₄ nanoparticles in the presence of a neodymium static magnetic field (about 9000 G). Pyrimidine, benzimidazole, quinoxaline, and benzodiazepine derivatives were swiftly synthesized at ambient temperature with excellent efficiency; no reaction transpired in the absence of a magnetic field. TEM and VSM investigations validated nanoscale dimensions (9–50 nm) and robust magnetic characteristics, facilitating efficient catalysis and straightforward recovery. The produced compounds were validated using FT-IR, 1H NMR, 13C NMR, and elemental analysis. The technology markedly decreased reaction time, reduced energy consumption, eliminated hazardous chemicals, and offers a sustainable pathway for synthesizing physiologically relevant heterocycles. Keywords Neodymium magnetic, Static magnetic field, Nano particles, Green chemistry, Azines Abbreviations SMF Static magnetic field TEM Transmission electron microscopy VSM Vibrating sample magnetometer NPs Nanoparticles The advancement of eco-friendly, sustainable synthetic methods has become a primary goal in contemporary organic chemistry. The notion of green chemistry, articulated through the twelve principles established by Anastas and Warner, underscores the reduction of waste, atom economy, the utilization of cleaner solvents, energy efficiency, and the preference for catalytic over stoichiometric reagents. These concepts seek to minimize the environmental impact of chemical processes while ensuring high efficiency, selectivity, and practicality in organic synthesis1–6. As a result, considerable efforts have been devoted to developing more environmentally friendly synthetic methods that reduce reliance on toxic chemicals and enhance overall process sustainability, as evidenced by recent research. Recent years have seen the development of several environmentally benign synthetic methods for organic transformations. These include methods such as electrochemical processes, visible-light photocatalysis, microwave-assisted synthesis, ultrasonic irradiation, and mechanochemical procedures like ball milling. Significant benefits in organic synthesis, such as increased selectivity, reduced solvent use, shorter reaction times, and higher yields, have been demonstrated using these techniques7–13. Several environmentally benign synthetic methods have been established for organic transformations, including microwave-assisted synthesis, ultrasonic irradiation, visible-light photocatalysis, electrochemical procedures, and mechanochemical processes such as ball milling14,15. These techniques offer significant benefits in organic synthesis, including shorter reaction times, higher yields, reduced solvent use, and greater selectivity. Notwithstanding these advancements, the persistent quest for more efficient, scalable, and ecologically sustainable techniques remains a pivotal factor in synthetic chemistry16–21. Nanotechnology has emerged as a powerful tool in green chemistry, offering innovative solutions for catalytic efficiency and process sustainability. In particular, nanocatalysts exhibit high surface area, enhanced reactivity, 1Higher Institution of Engineering & Modern Technology, Elmarg, Cairo 13774, Egypt. 2Department of Chemistry, Faculty of Science, Zagazig University, Zagazig 44519, Egypt. email: ; ; Scientific Reports | (2026) 16:15859 | https://doi.org/10.1038/s41598-026-51258-8 1 and excellent selectivity compared to bulk materials. Among them, magnetically recoverable nanocatalysts, especially Fe₃O₄-based systems, have gained significant attention due to their facile magnetic separation, recyclability, and operational simplicity22–26. These features make them highly attractive for sustainable organic transformations. Recent studies have revealed a diverse array of green organic transformations, encompassing reductive amination of carbonyl compounds, acylation reactions, multicomponent condensations, and heterocycle synthesis27–34, frequently conducted under solvent-free or mild conditions, yielding excellent results with minimal side reactions. Additionally, diverse advanced nanocatalysts, including silica-coated magnetic nanoparticles, molybdate-supported systems, and bio-derived or mixed-metal oxides, have demonstrated exceptional catalytic efficacy, operational ease, and substantial recyclability across numerous cycles without significant loss of activity. These advancements underscore the essential role of magnetic nanocatalysts in developing more environmentally friendly, efficient, and sustainable synthesis methods, highlighting their growing significance in contemporary organic chemistry35–41. Heterocyclic compounds constitute a crucial category of organic molecules in medical chemistry and pharmaceutical research. Over 90% of biologically active chemicals and commercial pharmaceuticals have at least one heterocyclic moiety within their molecular structure42–45. These heterocycles are not merely structural components; they are indispensable pharmacophores that modulate biological potency, refine pharmacokinetic profiles, and enhance binding affinities with specific molecular targets. Figure 1 summarizes key pharmacologically active heterocyclic scaffolds, including pyrimidine, benzimidazole, quinoxaline, and benzodiazepine, which form the structural basis of numerous therapeutic agents. To the best of our knowledge, the application of static external magnetic fields in combination with Fe₃O₄based nanocatalysts for enhancing organic transformations, particularly heterocyclic synthesis, remains underexplored. In this context, the present work introduces a novel and sustainable catalytic strategy that integrates Fe₃O₄ nanoparticles with a neodymium static magnetic field to enhance reaction efficiency under mild, eco-friendly conditions. This magnetic-field-assisted approach offers improved reaction rates, reduced reaction time, facile catalyst recovery, and excellent recyclability. This study aims to evaluate the effectiveness of this hybrid system in the synthesis of biologically relevant heterocyclic compounds as a green and efficient alternative to conventional methods, Fig. 2. Result and discussion Magnetic characterization of a neodymium magnet by VSM analysis The magnetic characteristics of the neodymium magnet were examined using the Vibrating Sample Magnetometer (VSM) method at ambient temperature (Fig. 3). The VSM analysis yields critical insights into the magnetic properties of materials by quantifying magnetization as a function of the applied magnetic field. The acquired hysteresis loop demonstrated that the neodymium magnet had robust magnetic prop (...truncated)