Thienyltriazine-based porous organic polymers with nitrogen rich moieties: synthesis and gas selectivity study

Abstract

Here, we present the synthesis of a series of thienyltriazine-containing nitrogen-rich porous organic polymers by making use of Sonogashira coupling reaction (for TT-CBz, TT-BCBz and TT-TPA) and FeCl₃-mediated polymerization (for TT-TCBz-(a–g)). The FeCl₃-mediated polymerization was performed under different reaction conditions, such as oxidative polymerization, Friedel–Crafts polymerization, and competitive oxidative/Friedel–Crafts polymerizations. Polymer TT-TCBz-b, synthesized at room temperature in the presence of FeCl₃ and MeNO₂, displayed the highest BET surface area of approximately 1059 m² g⁻¹. However, the percentage of micropore volume was largest for TT-TCBz-f and TT-TCBz-g, which can be attributed to their highly cross-linked structure. All of the polymers exhibited notable thermal stability, with the TT-TCBz series polymers reaching stability as high as 580 °C. The polymers of the TT-TCBz series were also used for CO₂ adsorption studies. The rich heteroatom content, presence of an electron-rich carbazole unit and high micropore volume make these polymers attractive candidates for sequestration of Lewis acidic CO₂ gas. A maximum CO₂ uptake of 16.5 wt% at 263 K and 100 kPa has been observed for TT-TCBz-g attributed to its high surface area and high percentage of micropore volume. IAST results further revealed that in TT-TCBz-g the selectivity for the CO₂ : N₂ mixture (15 : 85) is around 65.