Conjugated Microporous Polymer Nanosheets Functionalized with TEMPO Radicals as Efficient Heterogeneous Catalysts for Selective Aerobic Oxidation of Alcohols
Jiao Zhang, Xingyu Zhou, Huiling Mao, Zhongjie Yang, Junjie Zhang, Liang Xu, Jinliang Zhuang
Abstract
Thin-layered conjugated microporous polymers (CMPs) decorated with a high density of catalytic sites are ideal heterogeneous catalysts due to their high density and highly exposed catalytic sites, along with fast diffusion of substances. Despite extensive exploration, the synthesis of CMP nanosheets functionalized with covalently anchored organocatalytic units within the frameworks remains a significant challenge, particularly for efficient heterogeneous catalysts in oxidation reactions. In this article, the 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radical was covalently incorporated into CMP nanosheets through a Sonogashira coupling reaction. The employment of 1,3,6,8-tetraethynylpyrene (TEP) monomer is key to achieving nanosheet-like CMPs, owing to the strong π–π stacking interactions between the pyrene units. The resulting CMP-TEMPO nanosheets exhibit remarkable catalytic activity in the aerobic oxidation of aromatic and heteroatomic alcohols with excellent selectivity. This work opens the way for the design and construction of high-density TEMPO radical functionalized CMPs as high-performance heterogeneous catalysts.