No abstract

The magnetic biocompatible rod-like ZnS/CuFe 2 O 4 /agar organometallic hybrid catalyst was designed and prepared based on a natural macromolecule (agar) through a green and convenient method using inexpensive, nontoxic, and easily available substances. Then, the as-prepared catalyst was characterized by several techniques such as Fourier transform-infrared spectroscopy, energy-dispersive X-ray analysis, scanning electron microscopy image, transmission electron microscopy, vibrating sample magnetometry curve, X-ray diffraction pattern, and thermogravimetric analysis. Eventually, the catalytic application of the ZnS/CuFe 2 O 4 /agar nanobiocomposite was assessed in sequential Knoevenagel condensation-Michael addition reaction of dimedone, malononitrile, and different substituted aromatic aldehydes for the synthesis of 2-amino-tetrahydro-4H-chromene-3-carbonitrile derivatives. Some notable strengths of this environmentally benign catalyst include simplicity of catalyst preparation and separation, affording desired products with satisfactory yields (81%-97%) in very short reaction times (3-18 min), and with no need for complicated work-up processes. Experimental tests showed that the catalyst can be successfully reused after five sequential runs without significant reduction in its catalytic efficiency. K E Y W O R D S 2-amino-tetrahydro-4H-chromene-3-carbonitrile, agar, catalytic synthesis, good reusability, ZnS/CuFe 2 O 4 /agar catalyst

By employing the naturally-originated molecule of creatine, Fe3O4@SiO2-creatine as an environmentally benign magnetic organometallic nanobiocatalyst was successfully prepared via a convenient and green route. Then to acquire an inclusive comprehension of different properties of the catalyst, it was studied by various characterization techniques such as FT‐IR, FE-SEM, TEM, EDX, XRD, and VSM analyses. It was found that the size distribution of nanoparticles was an average diameter size of 70 nm. To examine the catalytic activity, it was applied in sequential knoevenagel condensation-Michael addition room temperature reaction of dimedone, malononitrile, and different substituted aromatic aldehydes to produce a variety of 2-amino-tetrahydro-4H-chromene-3-carbonitrile derivatives in a single step. Among the multiple outstanding advantages that can be mentioned for this work, some of the most noticeable ones include: affording the products in short reaction times with high yields, operating the reaction at ambient conditions and ease of catalyst separation.

The tubular magnetic agar supported ZnS/CuFe2O4 nanocomposite was fabricated via a simple procedure. Next, various properties of this nanocomposite were studied by employing multiple characterization techniques including FT-IR, EDX, SEM, TEM,VSM, XRD, and TGA. Then, the catalytic and antibacterial applications were evaluated for the fabricated nanocomposite. Based on the experimental result, the nanocomposite showed excellent catalytic activity to promote the multicomponent reaction between ethyl acetoacetate, hydrazine hydrate, aromatic aldehydes, and malononitrile to synthesize a variety of dihydropyrano[2,3-c]pyrazole derivatives with high yields (89–95%) in acceptable reaction times (20–40 min) under mild reaction conditions. It can be efficiently recycled and re-work in six consequent runs without notable reduction in catalytic productiveness. Furthermore, its antibacterial activity was assessed against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) bacteria by the agar diffusion and plate-count methods. These results indicate that the width of the inhibition zone around the S. aureus (G+ bacterium) is more than that of E. coli (G− bacterium). Moreover, the agar supported ZnS/CuFe2O4 nanocomposite exhibited strong prevention of the bacterial colonies’ growth.

Integration of nanomaterials is an entirely new method to synthesis efficient catalysts. These compounds provided new characteristics and distinctive application which is not accessible in the single-particle nanostuctures. Although there is little catalytic activity in each component of the hybrid material, their hybrid displays much higher activity. Indeed, the presence of intermediate metal and their oxides in the framework of hybrid catalyst caused a synergistic effect, thus facilitate the organic reaction more effectively. The extensive biochemical and pharmacological activities of imidazole-containing compounds have required the development of efficient methods for synthesizing these compounds, which is a significant topic in organic chemistry. The imidazole nucleus function as a main scaffold for constructing of biologically important molecules. The ZnS/CuFe2O4 magnetic hybrid nanocatalyst was synthesized by a simple co precipitation and characterized by conventional analyses successfully. Synthesized nanocomposite was utilized as a magnetic and heterogeneous catalyst for the one-pot synthesis of 2,4,5-triaryl-1H-imidazole derivatives with condensation of various aromatic aldehydes, benzil and ammonium acetate. The presented method shows some advantages such as mild conditions, good yields, and simple separation of products from the reaction mixture and cost-effective catalyst. The experimental data showed ZnS/CuFe2O4 nanocatalyst were easily separated from the reaction mixture using an external magnetic field and use again five times in subsequent reactions without appreciable reduction in catalytic activity.