Effect of Building Block Transformation in Covalent Triazine Based Frameworks for Enhanced CO2 Uptake and Metal Free Heterogeneous Catalysis.

Covalent Triazine Frameworks (CTFs) have provided a unique platform in functional material design for a wide range of applications. Herein, we report a series of new CTFs with two new heteroaromatic building blocks (pyrazole and isoxazole groups) aiming for carbon capture and storage (CCS) and catalysis. The CTFs were synthesized from their respective building blocks [(4,4'-(1H-pyrazole-3,5-diyl)dibenzonitrile (pyz) and 4,4'-(isoxazole-3,5-diyl)dibenzonitrile (isox))] under ionothermal conditions using ZnCl 2 . Both of the building blocks were designed by an organic transformation of an acetylacetone containing dinitrile linkers to pyrazole and isoxazole groups respectively. Due to this organic transformation, (i) linker aromatization, (ii) higher surface areas and nitrogen contents, (iii) higher aromaticity and (iv) higher surface basicity was achieved. Due to these enhanced properties, CTFs were explored for CO 2 uptake and metal free heterogeneous catalysis. Among all, the isox-CTF, synthesized at 400 °C, showed the highest CO 2 uptake (4.92 mmol/g at 273K and 2.98 mmol/g at 298 K at 1 bar). Remarkably, these CTFs showed excellent metal-free catalytic activity for the aerobic oxidation amine at mild reaction conditions. On studying the properties of the CTFs, it was observed that organic transformations and ligand aromatization of the materials are crucial factor to tune the important parameters that influence the CO 2 uptake and the catalytic activity.