Synthesis of Side-Chain-Free Hydrazone-Linked Covalent Organic Frameworks through Supercritical Carbon Dioxide Activation

• Main Authors: Shashini D. Diwakara, Gregory T. McCandless, Sampath B. Alahakoon, Ronald A. Smaldone
• Format: Article
• Language: English
• Published: Georg Thieme Verlag 2021-04-01
• Series: Organic Materials
• Subjects: covalent organic frameworks; hydrazones; supercritical carbon dioxide
• Online Access: http://www.thieme-connect.de/DOI/DOI?10.1055/a-1477-5123
• ISSN: 2625-1825

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.