Abstract
Supercritical carbon dioxide (scCO2 ) activation provides milder conditions to process covalent organic frameworks (COFs) without compromising their crystallinity and porosity. To this end, three hydrazone COFs (TFPB-DHz COF, TFPT-DHz COF, Py-DHz COF) were synthesized with a terephthaloyl dihydrazide linker (DHz ) which has no substituents. To date, the synthesis of hydrazone COFs without a narrow range of alkoxy linkers has not been possible. The scCO2 -activated hydrazone-linked COFs in this study were crystalline and had high surface areas (surface areas of TFPB-DHz COF, TFPT-DHz COF, and Py-DHz COF were 790, 1199, and 932 m2 /g, respectively). This study shows the significance of using milder activation methods for making hydrazone-linked COF structures that were previously inaccessible.
Key words covalent organic frameworks - hydrazones - supercritical carbon dioxide