Porous Metallosalen Hypercrosslinked Ionic Polymers for Cooperative CO₂ Cycloaddition Conversion

Abstract

Metallosalen-based porous ionic polymers have the potential to combine the merits of homogeneous organometallics and heterogeneous porous ionic catalysts in carbon dioxide (CO2) cycloaddition conversion. Herein, a series of porous metallosalen hypercrosslinked ionic polymers (M-HIPs) were synthesized through a simple method. The M-HIPs with high metal and Br anion concentrations were evaluated by catalyzing CO2 cycloaddition with epoxides. Because of the cooperative effect between Br anions and metal active species in the porous channel, M-HIPs exhibited a high CO2 catalytic performance even under ambient conditions. Among the M-HIPs (M = Co, Al, Zn), Co-HIP showed the best catalytic performance for various epoxides and was stable after five runs. Density functional theory calculations support the fact that Co-HIP had the lowest energy barrier, which agreed with the experimental results.

Emerging Ionic Polymers for CO

“…[18,[26][27][28] One efficient way is to utilize the unique advantages of ionic hyper-crosslinked polymers due to their large surface area, versatile architectures, and diverse ionic building blocks. [29,30] Wang et al synthesized imidazolium-functionalized hyper-crosslinked polymers (HCPs) using a series of benzylimidazole salts as the (charged) ionic monomers and a,a 0 -dibromo-p-xylene as a (neutral) crosslinking agent. [31] The connection between the phenyl ring and the imidazolium cation facilitated a hyper-crosslinking reaction through FeCl 3 -catalyzed Friedel-Crafts alkylation.…”

“…[51] Metallosalen-Based iPOPs Metallosalen-based PIPs combine the merits of both homogeneous organometallics and heterogeneous porous ionic catalysts for the CO 2 cycloaddition reaction. [30] In contrast to traditional metallosalen catalysts, incorporating metallosalen complexes into a porous framework containing free mobile anions can provide a co-operative environment to promote [46] Copyright Elsevier (2020).…”

“…[52] The nature of the metal, the spatial distance between the metal active site and the halogen anion, and the ratio of ionic:metal units in metallosalen-based iPOPs play a crucial role in the catalytic activity enhancement towards CO 2 cycloaddition. [30] In order to study the cooperative activation from the metal (Lewis acid) and halogen anions (nucleophile), Li et al prepared a series of porous metallosalen (M ¼ Co, Al, Zn) hyper-crosslinked ionic polymers by FriedelÀCrafts alkylation and quaternization. [30] Among them, the cobalt salen-based catalyst showed the highest activity.…”

“…[30] In order to study the cooperative activation from the metal (Lewis acid) and halogen anions (nucleophile), Li et al prepared a series of porous metallosalen (M ¼ Co, Al, Zn) hyper-crosslinked ionic polymers by FriedelÀCrafts alkylation and quaternization. [30] Among them, the cobalt salen-based catalyst showed the highest activity. Theoretical investigations revealed that the reduced energy barrier of the ring-opening process associated with Co is due to its efficient coordination with the oxygen atoms of epoxide compared with Al and Zn.…”

Hydroxylamino‐Anchored Poly(Ionic Liquid)s for CO2 Fixation into Cyclic Carbonates at Mild Conditions

“…[ 32 ] PILs fabricated from quaternization and F‐C alkylation was efficient in the CO 2 fixation, [ 33–36 ] it has gained a mushroom growth and was acting as an alternative for CO 2 fixation. [ 33–47 ] Also PILs based on imidazolium and bipyridine monomer were constructed and exhibited enhanced efficiency for generating of cyclic carbonates in the presence of zinc bromide. [ 48,49 ]…”