Iridium supported on porous polypyridine-oxadiazole as high-activity and recyclable catalyst for the borrowing hydrogen reaction

Homogenization of heterogeneous catalysts is a valuable and interesting research topic. Porous polypyridine-oxadiazole (PPO), as not only a carrier but also a ligand, was designed and synthesized from pyridine-oxadiazole and 1-iodo-4-vinylbenzene. Iridium was anchored onto the skeleton of this polymer (ligand) through coordination bonds. This porous polypyridine-oxadiazole iridium catalyst (PPO-Ir) was clearly characterized by XRD, BET, EDS, HRTEM, SEM, and XPS, and revealed high catalytic activity for the reaction of dimethyl-6-aminouracil with benzyl alcohols, 1,3-dimethylbarbituric acid with benzyl alcohols and 2-aminobenzylamine and benzyl alcohols through dehydrogenation and the borrowing hydrogen strategy with alcohol or water as the solvent. In addition, this PPO-Ir catalyst could be recycled and reused without a manifest loss of catalytic activity for at least five times and revealed potential application value. The mechanism explorations were further conducted to clarify this PPO-Ir and these transformations.

Automated summary

Homogenization of heterogeneous catalysts is a valuable and interesting research topic. In this study, a porous polypyridine-oxadiazole iridium catalyst was designed and synthesized, and it exhibited high catalytic activity in various reactions. The catalyst also showed the potential for recycling and reuse, indicating its promising application value. Mechanism explorations were conducted to understand the catalytic mechanism.