Abstract
Covalent organic frameworks (COFs) are defined as highly porous and crystalline polymers, constructed and connected via covalent bonds, extending in two- or three-dimension. Compared with other porous materials such as zeolite and active carbon, the versatile and alternative constituent elements, chemical bonding types and characteristics of ordered skeleton and pore, enable the rising large family of COFs more available to diverse applications including gas separation and storage, optoelectronics, proton conduction, energy storage and in particular, catalysis. As the representative candidate of next-generation catalysis materials, because of their large surface area, accessible and size-tunable open nano-pores, COFs materials are suitable for incorporating external useful active ingredients such as ligands, complexes, even metal nanoparticles deposition and substrate diffusion. These advantages make it capable to catalyze a variety of useful organic reactions such as important C-C bond formations. By appropriate pore-engineering in COFs materials, even enantioselective asymmetric C-C bond formations could be realized with excellent yield and ee value in much shorter reaction time compared with their monomer and oligomer analogues. This review will mainly introduce and discuss the paragon examples of COFs materials for application in C-C bond formation reactions for the organic synthetic purpose.
Highlights
C-C formation reaction catalyzed by we we review as catalysts in to realize the most meaningful organic transformations, namely, coupling reaction advances the utilization of covalent organic frameworks (COFs) as catalysts to realize the mostC-C
Developing heterogeneous catalysis, especially encapsulating the catalytically active species such as Pd, etc. into the pore space of porous materials like COFs with uncompromising catalytic efficiency will solve the issue of separating the toxic metal residues. (ii) From the prospect of catalytic efficiency, which is the core issue in catalysis, after binding metal active species, the metal catalytic center is confined by COFs pore
Up to 99% conversion ee with valuethe was realized when the heterogeneous catalytic reaction application to at catalysis that it was among the first main-chain chiral COFs fulfill asymmetric was conducted
Summary
Nanoporous materials possess extremely large surface areas, ordered pore channel structure, tunable active sites and functional groups [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20]. Even long-time immersing in these harsh conditions does not deteriorate its long-ordered structure and crystallinity This extraordinary stability is mainly attributed to that the skeleton structure was metal-free and constructed from strong covalent bonds, which possess much greater bond-dissociation-energy than coordinative bond in MOFs structure; (iii) the hydrogen bonding and π-π stacking interaction in COFs further strengthen the COFs skeleton and pore structure and prevent them from destruction by collective solvation, hydrolysis and redox presses in most catalytic cases; (iv) and more important, intrinsic COFs materials themselves have seldom active sites and/or catalytic activity as general regular catalysts to trigger C-H or C-X (X = Cl, Br, I, O, S, etc.) transformation for synthetic purpose. We believe that the advanced catalytic transformation strategies based on COFs catalysts will open up a new avenue to supplement the shortages of other transition-metal catalysis in C-C bond synthesis applications
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call