Multifunctional chiral cationic porous organic polymers: gas uptake and heterogeneous asymmetric organocatalysis

Abstract

Porous organic polymers (POPs) are of increasing interest as heterogeneous organocatalysts because they are robust, non-toxic, metal-free and environmentally friendly. Here, a series of chiral cationic porous organic polymers (CC-NSA_R-HCPs@X) obtained by a convenient and economical synthesis protocol not only have a high Brunauer–Emmett–Teller (BET) specific surface area (549–788 m² g⁻¹) and a satisfactory pore volume (0.422–0.618 cm³ g⁻¹), but also exhibit excellent thermal stability and chemical stability. Interestingly, we found that the chiral cationic network CC-NSA_Naph-HCP@Br serving as a metal-free, heterogeneous organocatalyst towards alkylation of N-(diphenylmethylene)glycerine tert-butyl ester with alkyl bromides displays high catalytic efficiency, wide substrate adaptability and good recyclability. Furthermore, by comparison, CC-NSA_Ph-HCP@Br is found to exhibit the highest hydrogen uptake due to its inherent ultra-microporous structure.