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<p>The application of nitrogen-rich metal–organic framework (N-rich MOF) and its magnetic composite in the aza-Michael reaction as a catalyst was investigated. The synthesis of anionic N-rich MOF, [CuBT(H<sub>2</sub>O)<sub>2</sub>]<sub>n</sub> (CuBT)) from the 5,5′-bistetrazole ligand (H<sub>2</sub>BT) to increase efficiency and reduce energy consumption was optimized using the hydrothermal method within 24&#xa0;h with a ratio of (ligand 3: metal salt 3: solvent 1). To increase the application and ease of separation, magnetite nanoparticles encapsulated in polyvinylpyrrolidone (Fe<sub>3</sub>O<sub>4</sub>@PVP) were stabilized on the surface of MOF (Fe<sub>3</sub>O<sub>4</sub>@PVP@CuBT) by sonication and hydrothermal methods. The materials were characterized using various analyses, including FT-IR, <sup>1</sup>H NMR, <sup>13</sup>C NMR, XRD, TEM, SEM, EDX &amp; mapping, BET-BJH, Zeta, DLS, VSM, and ICP. The composite exhibited a surface area (S<sub>BET</sub>) of 33.727 m<sup>2</sup>/g and an average pore diameter of 9.34&#xa0;nm. XRD analysis confirmed the successful synthesis of the MOF and the presence of magnetite peaks. ICP analysis determined that Fe<sub>3</sub>O<sub>4</sub>@PVP@CuBT contains 21.507% Cu and 6.197% Fe. VSM analysis showed that the composite has magnetic properties, with a saturation magnetization (M<sub>s</sub>) of 5.19&#xa0;emu/g, indicating its superparamagnetic behavior and ease of separation with a strong magnet. The catalytic properties of the MOF and its magnetic composite were evaluated in the aza-Michael reaction with different amines. Fe<sub>3</sub>O<sub>4</sub>@PVP@CuBT (3% W) demonstrated the highest conversion percentage (94%) as a strong and recyclable Lewis acid catalyst under mild conditions in the reaction of 2-vinyl pyridine with aniline.</p>

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Innovative application of high nitrogen magnetic MOF as a catalyst in the aza-Michael reaction

  • 期刊论文

  • 发表日期：

    2025年3月29日

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  • Elham Asadi,
  • Mohammad Bakherad,
  • Mohammad Hadi Ghasemi,
  • Alireza Shakeri,
  • Elmira Nasrollahi

摘要

The application of nitrogen-rich metal–organic framework (N-rich MOF) and its magnetic composite in the aza-Michael reaction as a catalyst was investigated. The synthesis of anionic N-rich MOF, [CuBT(H2O)2]n (CuBT)) from the 5,5′-bistetrazole ligand (H2BT) to increase efficiency and reduce energy consumption was optimized using the hydrothermal method within 24 h with a ratio of (ligand 3: metal salt 3: solvent 1). To increase the application and ease of separation, magnetite nanoparticles encapsulated in polyvinylpyrrolidone (Fe3O4@PVP) were stabilized on the surface of MOF (Fe3O4@PVP@CuBT) by sonication and hydrothermal methods. The materials were characterized using various analyses, including FT-IR, 1H NMR, 13C NMR, XRD, TEM, SEM, EDX & mapping, BET-BJH, Zeta, DLS, VSM, and ICP. The composite exhibited a surface area (SBET) of 33.727 m2/g and an average pore diameter of 9.34 nm. XRD analysis confirmed the successful synthesis of the MOF and the presence of magnetite peaks. ICP analysis determined that Fe3O4@PVP@CuBT contains 21.507% Cu and 6.197% Fe. VSM analysis showed that the composite has magnetic properties, with a saturation magnetization (Ms) of 5.19 emu/g, indicating its superparamagnetic behavior and ease of separation with a strong magnet. The catalytic properties of the MOF and its magnetic composite were evaluated in the aza-Michael reaction with different amines. Fe3O4@PVP@CuBT (3% W) demonstrated the highest conversion percentage (94%) as a strong and recyclable Lewis acid catalyst under mild conditions in the reaction of 2-vinyl pyridine with aniline.