Ni-citric acid coordination polymer as a practical catalyst for multicomponent reactions

Environmentally friendly detoxification of pistachios from aflatoxins using citric acid and Glycine-based bio-MOF

Aflatoxins are carcinogenic compounds that pose significant risks to food safety. Traditional removal methods often face challenges such as high chemical consumption, harsh conditions, and potential toxic byproducts. Eco-friendly solutions, such as solid-phase extraction with recyclable nanostructures, present a promising alternative due to their effectiveness, low cost, and minimal toxicity. In this study, an organic linker was synthesized from non-toxic compounds. This linker was then combined with CuCl2 for the preparation of a novel bio-MOF. The organic linker and bio-MOF were characterized. The bio-MOF's performance in removing aflatoxins from spiked solutions and contaminated pistachio extracts was evaluated under optimal conditions with aflatoxin concentrations measured by high-performance liquid chromatography. The results showed that the bio-MOF effectively removed over 95 % of aflatoxins in t < 10 min. Additionally, the recycled bio-MOF, after washing with solvent and reuse, maintained a significant portion of its efficiency, losing approximately 20 % of its initial performance after five consecutive uses.

Preparation of a Ni-ascorbic acid MOF as a recyclable catalyst for the synthesis of sulfoxides and tetrazoles

This study introduces a novel, cost-effective, and environmentally friendly approach for synthesizing a heterogeneous Ni-ascorbic acid metal-organic framework (Ni-ascorbic acid MOF) catalyst via a hydrothermal method. The catalyst was prepared by combining nickel nitrate (Ni(NO3)2·6H2O) and ascorbic acid (C6H8O6) in DMF. Comprehensive characterization of the synthesized Ni-ascorbic acid MOF was performed using FT-IR, XRD, EDX, BET, SEM, TGA/DSC, and AAS techniques. These analyses revealed that the catalyst exhibits a spherical microsphere morphology with high crystallinity, a specific surface area of 16.62 m2 g-1, a pore diameter of 19.52 nm, and excellent thermal stability. The catalytic performance of Ni-ascorbic acid MOF was investigated in two distinct reactions, including the selective oxidation of sulfides to sulfoxides and the synthesis of 5-substituted 1H-tetrazoles. Under optimized reaction conditions, the catalyst demonstrated high efficiency with product yields ranging from moderate to excellent across various substrates. Furthermore, the catalyst exhibited remarkable recyclability, maintaining its activity over five consecutive cycles without significant leaching of nickel species, as confirmed by hot filtration tests. These findings underscore the potential of a Ni-ascorbic acid MOF as a sustainable and robust catalyst for diverse organic transformations.

Synthesis, crystal structure and Hirshfeld analysis of a novel supra-molecular compound [Co(tsc)3]2[Co(cit)2](NO3)4·4H2O

A new cobalt complex, bis-[tris-(amino-thio-urea)cobalt(III)] bis-[2-(carb-oxy-methyl)-2-hy-droxy-butane-dioato]cobalt(II) tetra-nitrate tetra-hydrate, [Co(CH5N3S)3][Co(C6H6O7)2]0.5(NO3)2·2H2O, designated as [Co(tsc)3]2[Co(cit)2](NO3)4·4H2O, was synthesized. Two crystallographically independent cobalt centers are present. In the first, the central metal atom is chelated by three thio-semicarbazide ligands in a bidentate fashion whereas the second, positioned on a crystallographic inversion center, is hexa-coordinated by two citrate anions in a distorted octa-hedral geometry. Additionally, two water mol-ecules and two nitrate anions are present in the asymmetric unit. Hirshfeld surface analysis revealed that the presence of numerous donor and acceptor groups in the complex, which facilitate hydrogen-bonding inter-actions that contribute significantly to the overall cohesion of the crystal structure.

New Ionic Liquid Forms of Antituberculosis Drug Combinations for Optimized Stability and Dissolution

Isoniazid (INH) and rifampicin (RIF) are the two main drugs used for the management of tuberculosis. They are often used as a fixed drug combination, but their delivery is challenged by suboptimal solubility and physical instability. This study explores the potential of active pharmaceutical ingredient-ionic liquids (API-ILs) to improve the physicochemical and pharmaceutical properties of INH and RIF. Antitubercular drugs, INH, or RIF, were paired with different counter ions (ascorbic acid (AsA), citric acid (CA), tartaric acid (TA), benzoic acid (BA), salicylic acid (SA), and p-amino salicylic acid (PAS)) using the solvent evaporation method. INH and RIF API-ILs were formed successfully using AsA and CA counter ions. IL formation was examined and analyzed using Fourier transform infrared (FTIR) spectroscopy, x-ray powder diffraction (XRPD), and polarized optical microscopy (POM). XRPD and POM confirmed their amorphous nature, while FTIR analysis demonstrated the contribution of hydrogen bonding to IL formation. IL formation enhanced the storage stability of the INH + RIF mixture in the presence of CA. Moreover, RIF-CA IL significantly increased the rate and extent of RIF dissolution. An effect that is unattainable with the RIF/CA physical mixture. Thus, API-IL formation not only enhances RIF dissolution but also facilitates the preparation of stable, compatible INH-RIF combinations.

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.

Ultrasound-Promoted preparation and application of novel bifunctional core/shell Fe3O4@SiO2@PTS-APG as a robust catalyst in the expeditious synthesis of Hantzsch esters

In this work, D-(-)-α-phenylglycine (APG)-functionalized magnetic nanocatalyst (Fe₃O₄@SiO₂@PTS-APG) was designed and successfully prepared in order to implement the principles of green chemistry for the synthesis of polyhydroquinoline (PHQ) and 1,4-dihydropyridine (1,4-DHP) derivatives under ultrasonic irradiation in EtOH. After preparing of the nanocatalyst, its structure was confirmed by different spectroscopic methods or techniques including Fourier transform infrared (FTIR) spectroscopy, energy-dispersive X-ray spectroscopy (EDS), field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and thermal gravimetric analysis (TGA). The performance of Fe₃O₄@SiO₂@PTS-APG nanomaterial, as a heterogeneous catalyst for the Hantzsch condensation, was examined under ultrasonic irradiation and various conditions. The yield of products was controlled under various conditions to reach more than 84% in just 10 min, which indicates the high performance of the nanocatalyst along with the synergistic effect of ultrasonic irradiation. The structure of the products was identified by melting point as well as FTIR and ¹H NMR spectroscopic methods. The Fe₃O₄@SiO₂@PTS-APG nanocatalyst is easily prepared from commercially available, lower toxic and thermally stable precursors through a cost-effective, highly efficient and environmentally friendly procedure. The advantages of this method include simplicity of the operation, reaction under mild conditions, the use of an environmentally benign irradiation source, obtaining pure products with high efficiency in short reaction times without using a tedious path, which all of them address important green chemistry principles. Finally, a reasonable mechanism is proposed for the preparation of polyhydroquinoline (PHQ) and 1,4-dihydropyridine (1,4-DHP) derivatives in the presence of Fe₃O₄@SiO₂@PTS-APG bifunctional magnetic nanocatalyst.

Preparation and Characterization of a Coordination Polymer Based on Iron (III)-Cyamelurate as a Superior Catalyst for Heterogeneous Fenton-Like Processes

We report on a new iron (iii)-cyamelurate-based coordination polymer. The new material based on a heptazine derivative was prepared in aqueous medium and characterized by a variety of techniques including TGA, FTIR, XRD, HRTEM, and STEM. Due to the high structural stability of the complex in aqueous media, its heterogeneous Fenton-like catalytic activity was evaluated using a model molecule. The results obtained showed a high catalytic activity in both in basic and acid media. The pseudo-first-order rate constants normalized by iron(III) concentrations was approximately 1000 times higher than the result obtained for traditional heterogeneous catalysts based on iron(III) oxyhydroxides. The best observed catalytic activities were attributed to the increase in the binding sites of Fe³⁺ ions, in parallel with the increased exposure of the catalytic sites, leading to a higher atomic efficiency of the reaction.

Multicomponent Synthesis of Unsymmetrical Derivatives of 4-Methyl-Substituted 5-Nitropyridines

The multicomponent reaction of 2-nitroacetophenone (or nitroacetone), acetaldehyde diethyl acetal, β-dicarbonyl compound, and ammonium acetate in an acetic acid solution allowed the acquisition of previously undescribed 4-methyl-substituted derivatives of 5-nitro-1,4-dihydropyridine in satisfactory yields. The oxidation of the obtained 5-nitro-1,4-dihydropyridine derivatives resulted in the corresponding 2,4-dimethyl-5-nitropyridines. In addition, for the first time in the synthesis of unsymmetrical 1,4-dihydropyridines by the Hantzsch reaction acetaldehyde, diethyl acetal was used as a source of acetaldehyde. The use of more volatile and sufficiently reactive acetaldehyde in this reaction did not lead to a controlled synthesis of unsymmetrical 5-nitro-1,4-dihydropyridines. The proposed multicomponent approach to the synthesis of 4-methyl-substituted 5-nitro-1,4-dihydropyridines and their subsequent aromatization into pyridines made it possible to obtain previously undescribed and hardly accessible substituted 5(3)-nitropyridines.

Fe3O4/SiO2 decorated trimesic acid-melamine nanocomposite: a reusable supramolecular organocatalyst for efficient multicomponent synthesis of imidazole derivatives

This article describes supramolecular Fe3O4/SiO2 decorated trimesic acid-melamine (Fe3O4/SiO2-TMA-Me) nanocomposite that can be prepared with features that combine properties of different materials to fabricate a structurally unique hybrid material. In particular, we have focused on design, synthesis and evaluation a heterogeneous magnetic organocatalyst containing acidic functional-groups for the synthesis of biologically important imidazole derivatives in good to excellent yields. The introduced Fe3O4/SiO2-TMA-Me nanomaterial was characterized by different techniques such as FTIR, XRD, EDX, FESEM, TEM, TGA and DTA. As a noteworthy point, the magnetic catalytic system can be recycled and reused for more than seven consecutive runs while its high catalytic activity remains under the optimized conditions.