A Phenanthroline-Based Porous Organic Polymer for the Iridium-Catalyzed Hydrogenation of Carbon Dioxide to Formate
The Phenanthroline unit represents one of the most significant ligand frameworks in coordination chemistry. Constructing phenanthroline-based porous organic polymers with nonreactive functional groups in the polymer skeleton is a very promising goal in the field of heterogeneous catalysis, because it would offer a novel platform for doping molecular catalytic modules and generating single-site, stable, and porous heterogeneous catalytic entities for a wide range of catalytic applications. In this regard, a unique strategy to construct phenanthroline-based porous organic polymer (phen-POP) without other reactive/coordinating functional groups in the polymer skeleton has been designed for the first time, and synthesized via solvent knitting Friedel-Crafts polymerization method with a high BET surface area of 560 m2 g‒1. The well-defined and isolated phen sites of phen-POP can serve as a platform for immobilizing transition metal catalysts through N-N coordination bond. The post-synthetic metallation of iridium(III) chloride onto phen-POP afforded the highest active (initial turnover frequency of 40,000 h-1), simple and selective heterogeneous Ir catalyst for the hydrogenation of CO2 to formate. Thus, the work is significant in constructing novel POP-based heterogeneous catalysts for the development of industrially viable hydrogenation catalysts.