Carbamate-Isocyanurate-Bridged Periodic Mesoporous Organosilica for van der Waals CO₂ Capture

We synthesized a new organosiloxane bridge on the basis of an isocyanurate derivative through a simple melt-fusion approach by the reaction of 3-isocyanatopropyltriethoxysilane (IPTES) with 1,3,5-tris­(2-hydroxyethyl)-1,3,5-triazinane-2,4,6­(1H,3H,5H)-trione (THEIC). The obtained carbamate-isocyanurate-based organosiloxane bridge precursor was used for the preparation of chemo- and thermostable periodic mesoporous organosilica (PMO-THEIC) on condensation with tetrathoxysilane silicon precursor through a soft-template approach. Furthermore, the synthesized PMO-THEIC with unique surface functionality was investigated for CO₂ capture. The results show that the PMO-THEIC has higher activity than pure SBA-15 for CO₂ capture due to the high affinity of carbamate functionalities embedded within the pore walls toward CO₂ molecules. The affinity of organosiloxane bridge for CO₂ molecules is mainly facilitated via the van der Waals force with carbamate functional groups rather than the isocyanurate ring, according to the density functional calculations.