Conjugated Microporous Polymers with Extended π-Structures for Organic Vapor Adsorption

Abstract

Conjugated microporous polymers (CMPs), which are organic porous materials with π-conjugated skeletons, have attracted considerable attention in recent years owing to their distinct properties. Here, two sp2 carbon CMPs with analogous structures, namely, BO-CMP-1 and BO-CMP-2, were prepared through palladium-catalyzed Suzuki–Miyaura cross-coupling reaction. BO-CMP-1 and BO-CMP-2 possess high surface areas and can be further modulated by postoxidation reaction to form networks with enhanced rigidity, as denoted by oBO-CMP-1 and oBO-CMP-2, respectively. The oxidation process transforms biolefin benzoquinone blocks within the skeletons into tetrabenzocoronene segments and endows the resultant oBO-CMPs with extended π-structures. The postoxidation provides a feasible approach to obtain CMPs with large π-systems. This approach prevents the disadvantages of direct synthesis by using monomers with extended π-structures, which often suffers low polymerization degree from strong π–π stacking of the monomers. The N2 and CO2 adsorption analysis confirms the effective changes in the parent materials during the oxidation process, suggesting that the approach can well modulate the porosities and adsorption properties of CMPs. Furthermore, owing to their aromatic nature, BO-CMPs and oBO-CMPs exihibit good affinity toward aromatic molecules, showing high uptake of benzene and toluene. For example, BO-CMP-2 captures 112.5 wt % toluene and 95.0 wt % benzene at 298 K and P/P0 = 0.99, indicating their promising capability to remove toxic organic vapors.