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Porous organic polymers (POPs) incorporating macrocyclic units have been investigated in recent years in an effort to transfer macrocycles' intrinsic host–guest properties onto the porous networks to achieve complex separations. In this regard, highly interesting building blocks are presented by the family of cyclotetrabenzoin macrocycles with rigid, well-defined, electron-deficient cavities. This macrocycle shows high affinity towards linear guest molecules such as carbon dioxide, thus offering an ideal building block for the synthesis of CO2-philic POPs. Herein, we report the synthesis of a POP through the condensation reaction between cyclotetrabenzil and 1,2,4,5-tetraaminobenzene under ionothermal conditions using the eutectic zinc chloride/sodium chloride/potassium chloride salt mixture at 250 °C. Notably, following the condensation reaction, the macrocycle favors three-dimensional (3D) growth rather than a two-dimensional one while retaining the cavity. The resulting polymer, named 3D-mPOP, showed a highly microporous structure with a BET surface area of 1142 m2 g−1 and a high carbon dioxide affinity with a binding enthalpy of 39 kJ mol−1. Moreover, 3D-mPOP showed very high selectivity for carbon dioxide in carbon dioxide/methane and carbon dioxide/nitrogen mixtures. 

The development of porous materials is of great interest for the capture of CO₂from various emission sources, which is essential to mitigate its detrimental environmental impact. In this direction, porous organic polymers (POPs) have emerged as prime candidates owing to their structural tunability, physiochemical stability and high surface areas. In an effort to transfer an intrinsic property of a cyclotetrabenzoin‐derived macrocycle – its high CO₂affinity – into porous networks, herein we report the synthesis of three‐dimensional (3D) macrocycle‐based POPs through the polycondensation of an octaketone macrocycle with phenazine‐2,3,7,8‐tetraamine hydrochloride. This polycondensation was performed under ionothermal conditions, using a eutectic salt mixture in the temperature range of 200 to 300 °C. The resulting polymers, named 3D‐mmPOPs, showed reaction temperature‐dependent surface areas and gas uptake properties. 3D‐mmPOP‐250 synthesized at 250 °C exhibited a surface area of 752 m² g⁻¹and high microporosity originating from the macrocyclic units, thus resulting in an excellent CO₂binding enthalpy of 40.6 kJ mol⁻¹and CO₂uptake capacity of 3.51 mmol g⁻¹at 273 K, 1.1 bar.