The study reports on the synthesis and characterization of palladium-Isatin-Schiff base complex supported on graphene oxide (Pd-Isatin-Schiff base@rGO), as well as its application in the Sonogashira cross-coupling reaction. The catalyst was easily prepared by a simple method through modification of GO with (3-aminopropyl) triethoxysilane (APTES) as a linker. The reaction of free amine groups with isatin allowed the synthesis of Isatin-Schiff base@rGO. The subsequent complexation/immobilization of palladium provided the Pd-Isatin-Schiff base@rGO nanocomposite with a Pd(II) to Pd(0) ratio=1.17. The prepared Pd-Isatin-Schiff base@rGO nanocomposite was fully characterized by Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), CHN elemental analysis, scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), thermogravimetric analysis (TGA), high-resolution transmission electron microscope (HRTEM), X-ray photoelectron spectroscopy (XPS), and inductively coupled plasma optical emission spectroscopy (ICP-OES) to establish its structure and composition. This heterogeneous nanocomposite catalyst was found very efficient for the cross-coupling reaction of an alkyne and an aryl halide, generating a high yield of coupling products (80–95 %) after 1 h. A reusability study revealed that the Pd-Isatin-Schiff base@rGO composite could be recycled for six consequent cycles without significant loss of its activity. However, after six cycles, the yield of 1,2-diphenylethyne as the coupling product decreased slightly from 93 % to 85 % and a decrease 8 wt.% in the Pd content was observed using ICP analysis.

中文翻译：

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氧化石墨烯负载的钯-靛红-希夫碱络合物作为 Sonogashira 交叉偶联反应的催化剂

该研究报告了氧化石墨烯负载的钯-靛红-席夫碱配合物（Pd-靛红-席夫碱@rGO）的合成和表征，以及其在Sonogashira交叉偶联反应中的应用。该催化剂通过用(3-氨基丙基)三乙氧基硅烷(APTES)作为连接剂对GO进行修饰，通过简单的方法轻松制备。游离胺基团与靛红的反应可以合成靛红-希夫碱@rGO。随后钯的络合/固定提供了Pd-Isatin-Schiff碱@rGO纳米复合材料，其Pd(II)与Pd(0)比率=1.17。通过傅里叶变换红外光谱（FT-IR）、X射线衍射（XRD）、CHN元素分析、扫描电子显微镜（SEM）、场发射扫描电子显微镜对制备的Pd-Isatin-Schiff碱@rGO纳米复合材料进行了充分表征(FESEM)、能量色散光谱 (EDS)、热重分析 (TGA)、高分辨率透射电子显微镜 (HRTEM)、X 射线光电子能谱 (XPS) 和电感耦合等离子体发射光谱 (ICP-OES) 来建立它的结构和组成。人们发现这种非均相纳米复合催化剂对于炔烃和芳基卤化物的交叉偶联反应非常有效，1小时后产生高产率的偶联产物（80-95%）。可重复使用性研究表明，Pd-Isatin-Schiff base@rGO 复合材料可以循环利用六个后续循环，而不会显着丧失其活性。然而，经过六个循环后，作为偶联产物的 1,2-二苯乙炔的产率从 93% 略有下降至 85%，并且使用 ICP 分析观察到 Pd 含量减少了 8 wt.%。