Imine-linked covalent organic frameworks coordinated with nickel for ethylene oligomerization

The functionalized covalent organic framework materials play an important role in catalytic application. A convenient tactic is developed to design and synthesize an imine-linked covalent organic frameworks (COFs) material (COF-PD) with abundant nitrogen atoms, which can provide coordination active site and facilitate the incorporation of COFs with nickel ions. Nickel-coordinated COF-PD complex (COF-PD-Ni) is prepared and used in ethylene oligomerization. COF-PD-Ni displays the highest catalytic activity of 1.98 x 10(5) g/(mol center dot Ni center dot h) in ethylene oligomerization with MAO as co-catalyst and cyclohexane as solvent. Various reaction parameters including reaction temperature, time, solvent, and the amount of cocatalyst are evaluated in detail, dramatically impacting the catalytic activities as well as the distribution of the products. What is more, the effect of COFs structure on the catalytic performance is also studied, suggesting more coordination sites were more important for high activity.