Synthesis of Calix[4]arene‐Based Porous Organic Cages and Their Gas Adsorption

Abstract

AbstractTwo crystalline large‐sized porous organic cages (POCs) based on conical calix[4]arene (C4A) were designed and synthesized. The four‐jaw C4A unit tends to follow the face‐directed self‐assembly law with the planar triangular building blocks such as tris(4‐aminophenyl)amine (TAPA) or 1,3,5‐tris(4‐aminophenyl)benzene (TAPB) to generate a predictable cage with a stoichiometry of [6+8]. The formation of the large cages is confirmed through their relative molecular mass measured using MALDI‐TOF/TOF spectra. The protonated molecular ion peaks of C4A‐TAPA and C4A‐TAPB were observed at m/z 5109.0 (calculated for C336H240O24N32: m/z 5109.7) and m/z 5594.2 (calculated for C384H264O24N24: m/z 5598.4). C4A‐POCs exhibit I‐type N2 adsorption‐desorption isotherms with the BET surface areas of 1444.9 m2 ⋅ g−1 and 1014.6 m2 ⋅ g−1. The CO2 uptakes at 273 K are 62.1 cm3 ⋅ g−1 and 52.4 cm3 ⋅ g−1 at a pressure of 100 KPa. The saturated iodine vapor static uptakes at 348 K are 3.9 g ⋅ g−1 and 3.5 g ⋅ g−1. The adsorption capacity of C4A‐TAPA for SO2 reaches to 124.4 cm3 ⋅ g−1 at 298 K and 1.3 bar. Additionally, the adsorption capacities of C4A‐TAPA for C2H2, C2H4, and C2H6 were evaluated.