Hyper-crosslinked beta-cyclodextrin porous polymer: an adsorption-facilitated molecular catalyst support for transformation of water-soluble aromatic molecules

A hyper-crosslinked beta-cyclodextrin porous polymer (BnCD-HCPP) was designed and synthesized facilely by beta-cyclodextrin benzylation and subsequent crosslinking via a Friedel-Crafts alkylation route. The BnCD-HCPP shows an extremely high BET surface area, large pore volume, and high thermal stability, making it a highly efficient adsorbent for removal of aromatic pollutants from water. The adsorption efficiency in terms of distribution coefficient, defined as the ratio of adsorption capacity to equilibrium adsorbate concentration, ranged from 103 to 106 mL g(-1) within a concentration of 0-100 ppm, one order of magnitude higher than that of other beta-cyclodextrin-based adsorbents reported previously. The molar percentage of adsorbate to beta-cyclodextrin exceeded 300%, suggesting that the adsorption occurred not only in the cyclodextrin cavities via a 1 : 1 complexation, but also in the nanopores of the BnCD-HCPP created during the hyper-crosslinking. The BnCD-HCPP can be further functionalized by incorporation of gold nanoparticles for catalytic transformation of adsorbed phenolic compounds such as 4-nitrophenol to 4-aminophenol.