In this study, nanoparticles of CuFe₂O₄@SiO₂@PTMS@Tu@Ni(II) as the reusable magnetic catalyst were prepared. Synthesis of the Ni(II)–CuFe₂O₄ system was carried out through a five-step procedure including the preparation of CuFe₂O₄ as the prime magnetic core, layering of silica, 3-chloropropyltrimethoxysilane and thiourea and finally the immobilization of Ni(OAc)₂·4H₂O. The prepared nanocomposite system was then characterized using FT-IR, SEM, EDX, XRD, VSM, ICP-OES and TGA/DSC analyses. Catalytic activity of CuFe₂O₄@SiO₂@PTMS@Tu@Ni(II) was further studied toward synthesis of biscoumarin materials by a domino Knoevenagel–Michael reaction of 4-hydroxycoumarin with aromatic and heterocyclic aldehydes under solvent-free conditions (70 °C) within 15–30 min. The applied nanocomposite system was easily and magnetically separated from the reaction mixture and reused for six consecutive cycles without the significant loss of its catalytic activity.

中文翻译：

---

硫脲官能化的铜铁氧体上固定化的Ni（II）物种：无溶剂条件下合成双香豆素的可重复使用的纳米催化剂

本研究制备了可重复使用的磁性催化剂CuFe ₂ O ₄ @SiO ₂ @ PTMS @ Tu @ Ni（II）。在Ni（II）-CuFe的合成₂ ö ₄系统通过包括准备的CuFe的五个步骤进行₂ ø ₄作为主磁心，二氧化硅，3-氯丙基和硫脲，最后的固定化的分层的Ni（OAc）₂ ·4H ₂ O的制备纳米复合材料然后系统用FT-IR，SEM，EDX，XRD，VSM，ICP-OES和TGA / DSC分析表征。CuFe ₂ O ₄ @SiO _2的催化活性@ PTMS @ Tu @ Ni（II）在无溶剂条件下（70°C）在15-30分钟内通过4-羟基香豆素与芳香族和杂环醛的多米诺Knoevenagel-Michael反应对合成双香豆素材料进行了进一步研究。所施加的纳米复合材料体系可以轻松地从反应混合物中磁分离，并可以连续六个循环重复使用，而不会显着降低其催化活性。