porous organic polymers (POPs) connected through strong autologous covalent bonds from vinyl-polymerization are emerging as a family of advanced materials advantageous to MOFs, because of a relatively high thermal stability of the skeleton, a hierarchical porosity, as well as the structural diversity. [4] In addition, the ligands [4] or the functional sites [5] in POPs can serve as strong anchoring sites for different metals with great tunability of the metal properties via different preparation methods, being more suitable for cataly sis. It has been believed that the chemical bond between metal species and POPs can be a coordination or an ionic bond, and the latter is generally more stable particularly under harsh reaction conditions. In this context, an effective method to create strong ionic bond is by the immobilization of the ionic active sites onto a new type of POPs with charged skeleton balanced by counterions, coined herein as porous ionic polymers (PIPs). [5] Thanks to the strong bonding and the ionic nature, the resultant single-site metal catalysts can well inherit both the advantages of homo-and heterogeneous processes, i.e., the high activity of the former and the catalyst robustness of the latter. Herein, we first briefly introduce the preparation approaches for porous organic polymers and the corresponding strategies for heterogenization of homogeneous metallic catalysts, and then exemplify a PIP hosted single-site rhodium catalyst (Rh 1 /PIP) for vapor-phase methanol carbonylation, and its excellent performance shows a promising prospect in this exciting field.
POPs Polymerized by Vinyl-Based MonomersDifferent synthetic strategies have been developed to prepare POPs. [3,6] The widely used hard or soft-templates are supposed to be removed completely, requiring a highly complicated and energy-consuming procedure. [3] Moreover, the residual metals (Cu, Ni, etc.) as polymerization catalysts for Sonogashira, [7,8] Click, [9] and Yamamoto reactions [10] usually show negative impacts on the catalytic performance of POPs. Contrarily, the polymerization process of vinyl-based monomers is an exception, which can not only avoid the residue of templates and metals, but also offer excellent yields (near 100%) and simple operation. [11] Novel porous polymers can serve as self-supporting solid carriers and provide abundant coordination or charged sites for single-site metals, and thus are emerging as advanced functional materials in heterogeneous catalysis for various transformations traditionally catalyzed by homogeneous systems. A brief overview of the development of this heterogenization given, including the recent advances regarding electrovalent bonds by employing charged supports represented by porous ionic polymers (PIPs), which is exemplified herein with a novel single-site Rh 1 /PIP catalyst, featuring a new active site [Rh(CO)I 3 ] 2− dual-ionically bound onto a quaternary phosphonium cationic framework polymer, different from the single-ionically bound [Rh(CO) 2 I 2 ] − in previous studies. Such a u...
