Porous Polyketones with a Well-Defined 1,3,5-Triphenyloylbenzene Subunit via Cyclotrimerization of Enaminones for Gas Separations

Porous organic polymers (POPs) functionalized with carbonyl groups have attracted much attention not only due to the inherent properties of polyketones but also for their rich postfunctionalizations. However, the synthesis of porous polyketone is very limited, mainly through AlCl₃-mediated Friedel-Crafts acylation polymerization of aromatic hydrocarbons, which faced issues such as undefined polyacylation products, reactivity decreasing with polymerization going on, and the residual AlCl₃ in the polymers. In order to have a well-defined structure of porous polyketones to advance the research of porous materials, this Article developed cyclotrimerization polymerization of tris-enaminones to access a class of porous polyketones based on 1,3,5-triphenylacetylbenzene structural units named BIT-POP-80 ∼ BIT-POP-82, with a BET surface area up to 580 m² g^-1. Considering the affinity of the carbonyl group to CO₂, the as-synthesized porous polyketones were doped into the polysulfone matrix as a porous filler to make mixed matrix membranes (MMMs). It is found that the MMMs effectively improved the permeability of CO₂ by 150% as well as the gas pair selectivity of CO₂/CH₄. The cyclotrimerization polymerization of enaminones reported in this paper provided a powerful approach to functionalized porous polymer materials with well-defined structure.