Zeynizadeh B, Rahmani S. Immobilized copper-layered nickel ferrite on acid-activated montmorillonite, [(NiFe2O4@Cu)(H+-Mont)], as a superior magnetic nanocatalyst for the green synthesis of xanthene derivatives.
RSC Adv 2019;
9:28038-28052. [PMID:
35558991 PMCID:
PMC9092614 DOI:
10.1039/c9ra04320a]
[Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2019] [Accepted: 08/22/2019] [Indexed: 11/23/2022] Open
Abstract
In this study, the immobilization of copper-layered nickel ferrite on the surface and in the cavities of acid-activated montmorillonite (H+-Mont) was investigated. In this context, magnetic nanoparticles (MNPs) of NiFe2O4 as the prime magnetic cores were prepared. Next, through the reduction of Cu2+ ions with sodium borohydride, the nanoparticles of Cu0 were immobilized on the nanocore-surface of NiFe2O4, and the constituent NiFe2O4@Cu MNPs were obtained. Moreover, through the activation of montmorillonite K10 (Mont K10) with HCl (4 M) under controlled conditions, the H+-Mont constituent was prepared. The nanostructured NiFe2O4@Cu was then intercalated within the interlayers and on the external surface of the H+-Mont constituent to afford the novel magnetic nanocomposite (NiFe2O4@Cu)(H+-Mont). The prepared clay nanocomposite was characterized using FTIR spectroscopy, SEM, EDX, XRD, VSM and BET analyses. The obtained results showed that through acid-activation, the stacked-sheet structure of Mont K10 was exfoliated to tiny segments, leading to a significant increase in the surface area and total pore volume of the H+-Mont constituent as compared to those of montmorillonite alone. SEM analysis also exhibited that the dispersion of NiFe2O4@Cu MNPs in the interlayers and on the external surface of acid-activated montmorillonite was carried out successfully, and the nanoparticle sizes were distributed in the range of 15–25 nm. The BET surface analysis also indicated that through the immobilization of NiFe2O4@Cu MNPs, the surface area and total pore volume of the H+-Mont system were decreased. The catalytic activity of (NiFe2O4@Cu)(H+-Mont) was further studied towards the synthesis of substituted 13-aryl-5H-dibenzo[b,i]xanthene-5,7,12,14(13H) tetraones 3(a–k) and 3,3,6,6-tetramethyl-9-aryl-3,4,5,6,7,9-hexahydro-1H-xanthene-1,8(2H) diones 5(a–k)via the pseudo-one-pot three-component cyclocondensation of 2-hydroxy-1,4-naphthoquinone (Lawsone)/dimedone and aromatic aldehydes in a mixture of H2O–EtOH (1 : 1 mL) as a green solvent at 80–90 °C. The (NiFe2O4@Cu)(H+-Mont) MNPs can be easily separated from the reaction mixture by an external magnetic field and reused for seven consecutive cycles without significant loss of catalytic activity.
In this study, the catalytic activity of the prepared (NiFe2O4@Cu)(H+-Mont) MNPs was studied towards the synthesis of dibenzo[b,i]xanthene tetraones 3(a–k) and hexahydroxanthene diones 5(a–k).![]()
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