A N-heterocyclics induced π-π interaction strategy to synthesis hyper-crosslinked polymers with enhanced porosity for xenon adsorption

Hyper-crosslinked polymers (HCPs) with large specific surface areas play an important role in gas adsorption and separation. However, the method to enhance the specific surface area of HCPs and gas adsorption performance without changing the polyaromatic hydrocarbons (PAHs) monomer structure and reaction condition is still missing. Here, we present a general and facile N-heterocyclics induced π-π interaction strategy to increase the specific surface area of HCPs by simply adding N-heterocyclics during the Friedel-Crafts alkylation reaction. The specific surface areas of HCP (tetraphenylmethane based HCPs, TPMBPy-TCM) increased up to 7.78 times compared to the one without adding N-heterocyclics. The crosslinking and stacking of PAHs was influenced by the π-π stacking between the N-heterocyclic complexes and PAHs. More importantly, N-heterocyclics coordinated with Lewis acids have lower electron density and do not react with PAHs in the Friedel-Crafts alkylation reaction, which can be removed easily from HCPs. The HCPs obtained shown good xenon adsorption performance with Xe uptake of 3.63 mmol/g, which is the highest value for organic adsorbents reported in literature. This work provides new insight into the preparation of high-performance HCPs.