Heptazine-Based Porous Framework for Selective CO2 Sorption and Organocatalytic Performances

A new heptazine-based polymer network (Cy-pip) with highly rich nitrogen sites has been synthesized via catalyst-free direct coupling of cyameluric chloride (Cy) and piperazine (Pip). Cy-pip exhibits large CO2 uptake capacity (103.4 mg/g, 9.4 wt %, 1 bar/273 K) with high selectivity (117) toward CO2 over N2. Furthermore, this framework with high Lewis basic nitrogen sites has also been exploited as heterogeneous catalyst for Knoevenagel reaction of aromatic and heterocyclic aldehydes with active methylene compounds. Moreover, the catalyst can recycle up to four times with only a minor loss of activity.