Synthesis and Characterization of Nickel Metal-Organic Framework Including 4,6-diamino-2-mercaptopyrimidine and its Catalytic Application in Organic Reactions

A novel recyclable hydrolyzed nanomagnetic copolymer catalyst for green, and one-pot synthesis of tetrahydrobenzo[b]pyrans

Polymer-based catalysts have garnered significant interest for their efficiency, reusability, and compatibility with various synthesis processes. In catalytic applications, polymers offer the advantage of structural versatility, enabling functional groups to be tailored for specific catalytic activities. In this study, we developed a novel magnetic copolymer of methyl methacrylate and maleic anhydride (PMMAn), synthesized via in situ chemical polymerization of methyl methacrylate onto maleic anhydride, using benzoyl peroxide as a free-radical initiator. This polymerization process results in a robust copolymer matrix, which was subsequently hydrolyzed in an alkaline aqueous solution to introduce additional functional groups, yielding hydrolyzed PMMAn. These functional groups enhance the copolymer's ability to support the deposition of magnetic nanoparticles and participate in catalytic reactions. Following hydrolysis, we fabricated a unique magnetic composite, Fe3O4@Hydrol-PMMAn, by in situ coprecipitating Fe3O4 nanoparticles onto the hydrolyzed copolymer, creating a stable nanocatalyst. The structural and magnetic properties of Fe3O4@Hydrol-PMMAn were thoroughly analyzed using FTIR, XRD, SEM, EDX, VSM, and TGA. The Fe3O4@Hydrol-PMMAn nanocatalyst demonstrated remarkable catalytic performance in synthesizing tetrahydrobenzo[b]pyran derivatives through a three-component reaction, conducted without solvents to support green chemistry principles. A series of reaction parameters were optimized, including solvent choice, catalyst loading, and recyclability. The catalyst performed efficiently across a broad range of aldehydes, delivering high product yields (81-96%) with rapid reaction times (5-30 min) at a low catalyst loading of 0.015 g. A hot filtration test confirmed the heterogeneous nature of the nanocatalyst, which could be recycled up to four cycles with minimal loss in activity. The high yield, short reaction time, solvent-free conditions, and excellent reusability make Fe3O4@Hydrol-PMMAn a promising catalyst. These findings underscore its potential for converting waste products into valuable compounds, highlighting its utility in organic transformations and sustainable synthesis practices. Collectively, this work demonstrates that Fe3O4@Hydrol-PMMAn is highly effective for organic compound synthesis, advancing the development of versatile, sustainable nanocatalysts.

A multidentate copper complex on magnetic biochar nanoparticles as a practical and recoverable nanocatalyst for the selective synthesis of tetrazole derivatives

Waste recycling, novel and easy methods of recycling catalysts, use of green solvents, use of selective catalysts and preventing the production of by-products are the most important principles of green chemistry and modern technology. Therefore, in this work, biochar nanoparticles (B-NPs) were synthesized by the pyrolysis of chicken manure as a novel method for waste recycling. Subsequently, the B-NPs were magnetized by Fe(0) nanoparticles to improve the easy recovery of biochar. Then, the surface of biochar magnetic nanoparticles (FeB-MNPs) was modified by (3-chloropropyl)trimethoxysilane (3Cl-PTMS). Finally, a multidentate copper complex of 2,2'-(propane-1,3-diylbis(oxy))dianiline (P.bis(OA)) was immobilized on the surface of modified FeB-MNPs, which was labeled as Cu-P.bis(OA)@FeB-MNPs. Cu-P.bis(OA)@FeB-MNPs was investigated as a commercial, homoselective, practical, and recyclable nanocatalyst in the synthesis of 5-substituted-1H-tetrazole compounds through the [3 + 2] cycloaddition of sodium azide (NaN3) and organo-nitriles in polyethylene glycol 400 (PEG-400) as a green solvent. Cu-P.bis(OA)@FeB-MNPs was characterized using wavelength dispersive X-ray (WDX) spectroscopy, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), energy-dispersive X-ray spectroscopy (EDS), vibrating-sample magnetometer (VSM), atomic absorption spectroscopy (AAS) and N2 adsorption-desorption (Brunauer-Emmett-Teller (BET) method) techniques. Cu-P.bis(OA)@FeB-MNPs was recovered and reused for several runs in the synthesis of tetrazoles.

3-(Sulfamic acid)-propyltriethoxysilane on biochar nanoparticles as a practical, biocompatible, recyclable and chemoselective nanocatalyst in organic reactions

Recyclable and inexpensive catalysts, waste regeneration, use of available and safe solvents are important principles of green chemistry. Therefore, in this project, biochar nanoparticles (BNPs) were synthesized by the pyrolysis method from chicken manure. Then, 3-(sulfamic acid)-propyltriethoxysilane (SAPES) was immobilized on the surface of BNPs (SAPES@BNPs). The prepared catalyst (SAPES@BNPs) was used as a commercial, practical, biocompatible and reusable catalyst in the selective oxidation of sulfides to sulfoxides. Further, the catalytic application of SAPES@BNPs was explored in the multicomponent synthesis of tetrahydrobenzo[b]pyrans under mild and green conditions. BNPs were characterized using SEM, TGA and XRD techniques. SAPES@BNPs were characterized using SEM, FT-IR spectroscopy, WDX, EDS, TGA, and XRD techniques. Particle size distribution was obtained by histogram graph. SAPES@BNPs can be recovered and reused several times. The purity of the products was studied using NMR spectroscopy.

Immobilization of Ni(ii) complex on the surface of mesoporous modified-KIT-6 as a new, reusable and highly efficient nanocatalyst for the synthesis of tetrazole and pyranopyrazole derivatives

In this paper, KIT-6@SMTU@Ni was successfully synthesized via a new method of Ni(ii) complex stabilization on modified mesoporous KIT-6, as a novel and green heterogeneous catalyst. The obtained catalyst (KIT-6@SMTU@Ni) was characterized using Fourier transform infrared spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET) calculation, X-ray diffraction (XRD), atomic absorption spectroscopy (AAS), energy-dispersive X-ray spectroscopy (EDS), X-ray mapping, thermogravimetric analysis (TGA) techniques and scanning electron microscopy (SEM). After complete characterization of the catalyst, it was successfully used for the synthesis of 5-substituted 1H-tetrazoles and pyranopyrazoles. Moreover, tetrazoles were synthesized from benzonitrile derivatives and sodium azide (NaN₃). All tetrazole products were synthesized with high TON, TOF and excellent yields (88-98%) in a reasonable time (0.13-8 h), demonstrating the efficiency and practicality of the KIT-6@SMTU@Ni catalyst. Furthermore, pyranopyrazoles were prepared through the condensation reaction of benzaldehyde derivatives with malononitrile, hydrazine hydrate and ethyl acetoacetate with high TON, TOF and excellent yields (87-98%) at appropriate times (2-10.5 h). KIT-6@SMTU@Ni could be reused for five runs without any re-activation. Significantly, this plotted protocol has prominent benefits, such as applying green solvents, the use of commercially available and low-cost materials, excellent separation and reusability of the catalyst, short reaction time, high yield of products and a facile work-up.

A new samarium complex of 1,3-bis(pyridin-3-ylmethyl)thiourea on boehmite nanoparticles as a practical and recyclable nanocatalyst for the selective synthesis of tetrazoles

Boehmite is a natural and environmentally friendly compound. Herein boehmite nanoparticles were primarily synthesized and, then, their surface were modified via 3-choloropropyltrimtoxysilane (CPTMS). Afterwards, a new samarium complex was stabilized on the surface of the modified boehmite nanoparticles (Sm-bis(PYT)@boehmite). The obtained nanoparticles were characterized using thermogravimetric analysis (TGA), energy dispersive X-ray spectroscopy (EDS), Brunauer-Emmett-Teller (BET), wavelength dispersive X-ray spectroscopy (WDX), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR), Inductively coupled plasma mass spectrometry (ICP-MS), dynamic light scattering (DLS), and X-ray diffraction (XRD) pattern. Sm-bis(PYT)@boehmite was used as an environmentally friendly, efficient, and organic-inorganic hybrid nanocatalyst in the homoselective synthesis of tetrazoles in polyethylene glycol 400 (PEG-400) as a green solvent. Notably, Sm-bis(PYT)@boehmite is stable and has a heterogeneous nature. Thus, it can be reused for several runs without any re-activation.

Synthesis of tetrazoles catalyzed by a new and recoverable nanocatalyst of cobalt on modified boehmite NPs with 1,3-bis(pyridin-3-ylmethyl)thiourea

In the first part of this work, boehmite nanoparticles (BNPs) were synthesized from aqueous solutions of NaOH and Al(NO₃)₃·9H₂O. Then, the BNPs surface was modified using 3-choloropropyltrimtoxysilane (CPTMS) and then 1,3-bis(pyridin-3-ylmethyl)thiourea ((PYT)₂) was anchored on the surface of the modified BNPs (CPTMS@BNPs). In the final step, a complex of cobalt was stabilized on its surface (Co-(PYT)₂@BNPs). The final obtained nanoparticles were characterized by FT-IR spectra, TGA analysis, SEM imaging, WDX analysis, EDS analysis, and XRD patterns. In the second part, Co-(PYT)₂@BNPs were used as a highly efficient, retrievable, stable, and organic-inorganic hybrid nanocatalyst for the formation of organic heterocyclic compounds such as tetrazole derivatives. Co-(PYT)₂@BNPs as a novel nanocatalyst are stable and have a heterogeneous nature; therefore, they can be recovered and reused again for several consecutive runs without any re-activation.

A Schiff base complex of lanthanum on modified MCM-41 as a reusable nanocatalyst in the homoselective synthesis of 5-substituted 1H-tetrazoles

In this work, mesoporous MCM-41 was modified by a new Schiff-base formed from the condensation of triethylenetatramine and 5-bromosalicylaldehyde. Then, it was used for the stabilization of lanthanum metal (La-Schiff base@MCM-41) as a homoselective, reusable, efficient and biocompatible catalyst in the synthesis of 5-substituted 1H-tetrazole derivatives. The synthesized tetrazoles were characterized using ¹H NMR and FT-IR spectroscopy and methods to measure their physical properties. La-Schiff base@MCM-41 was characterized by using various techniques such as ICP, CHN, XRD, TGA, BET, FT-IR spectroscopy, SEM, EDS and WDX. This catalyst has good stability and a heterogeneous nature, enabling it to be easily recovered and reused several times without significant loss in catalytic activity. This present strategy has important advantages such as utilizing PEG as a green solvent, short reaction times, excellent yields, easy recycling of the catalyst and pure separation of the products. The recovered La-Schiff base@MCM-41 catalyst was characterized by using FT-IR spectroscopy, SEM and AAS.