Aerobic epoxidation of alkene is a green and economical route to produce epoxides. For such reaction, transition metal complexes exhibit favorable catalytic activity. In this work, NH2-MIL-101, a stable metal–organic framework (MOF) material with large surface area and high pore volume, was functionalized with pyridine-2,6-dicarbaldehyde and Co(NO3)2, to realize the immobilization of Co(II) via imine–pyridine–carbonyl (N,N,O) tridentate ligands bonding to MOF skeleton. The modified materials were applied as heterogeneous catalysts for the aerobic epoxidation of cyclohexene at ambient temperature, and multiple factors were studied to explore their influences on catalytic effects. Under the optimal reaction conditions, satisfactory substrate conversion and epoxide selectivity were reached. In addition, this catalytic system is suitable for a variety of alkene substrates. Furthermore, recycle experiments and infrared spectroscopy characterization illustrated that the coordination surroundings of Co are altering smoothly during the reaction process, thus having an impact on the performance of catalyst.

中文翻译：

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钴亚胺-吡啶-羰基络合物功能化金属-有机骨架作为烯烃环氧化的催化剂

烯烃的好氧环氧化是生产环氧化物的一种绿色、经济的途径。对于这样的反应，过渡金属配合物表现出良好的催化活性。在这项工作中，NH2-MIL-101 是一种稳定的金属有机骨架 (MOF) 材料，具有大表面积和高孔容，用吡啶-2,6-二甲醛和 Co(NO3)2 进行功能化，以实现固定化。 Co(II) 通过亚胺-吡啶-羰基 (N,N,O) 三齿配体键合到 MOF 骨架。将该改性材料作为环己烯好氧环氧化反应的多相催化剂，研究了多种因素对催化效果的影响。在最佳反应条件下，达到了令人满意的底物转化率和环氧化物选择性。此外，该催化体系适用于多种烯烃底物。此外，循环实验和红外光谱表征表明，Co 的配位环境在反应过程中发生了平滑的变化，从而对催化剂的性能产生了影响。