Porous Organic Polymers Derived from Ferrocene and Tetrahedral Silicon-Centered Monomers for Carbon Dioxide Sorption

Herein, we present two novel ferrocene-containing porous organic polymers, FPOP-1 and FPOP-2, by the Heck reactions of 1,1'-divinylferrocene with two tetrahedral silicon-centered units, i.e., tetrakis(4-bromophenyl)silane and tetrakis(4'-bromo-[1,1'-biphenyl]-4-yl)silane. The resulting materials possess high thermal stability and moderate porosity with the Brunauer-Emmer-Teller (BET) surface areas of 499 m² g^-1 (FPOP-1) and 354 m² g^-1 (FPOP-2) and total pore volumes of 0.43 cm³ g^-1 (FPOP-1) and 0.49 cm³ g^-1 (FPOP-2). The porosity is comparable to previously reported ferrocene-containing porous polymers. These materials possess comparable CO₂ capacities of 1.16 mmol g^-1 (5.10 wt%) at 273 K and 1.0 bar, and 0.54 mmol g^-1 (2.38 wt%) at 298 K and 1.0 bar (FPOP-1). The found capacities are comparable to, or higher than many porous polymers having similar or higher surface areas. They have high isosteric heats of up to 32.9 kJ mol^-1, proving that the affinity between the polymer network and CO₂ is high, which can be explained by the presence of ferrocene units in the porous networks. These results indicate that these materials can be promisingly utilized as candidates for the storage or capture of CO₂. More ferrocene-containing porous polymers can be designed and synthesized by combining ferrocene units with various aromatic monomers under this strategy and their applications could be explored.