Design and Synthesis of 3D Covalent Organic Frameworks

Abstract

<p>The results of the COP26 summit showed an increased commitment both from politicians and businessmen to phase out the production of internal combustion engines within the next two decades. Within this period, there is a need to provide solutions to the technological gaps to help lower the operational and manufacturing costs of zero emission vehicles and improve their marketability. Fuel cell vehicles have the greatest potential as the sustainable alternative for light and heavy vehicles. In line with this, this project aims to improve the hydrogen storage capacity of the tanks by using adsorbents made from stable, lightweight porous materials with high surface areas, by designing and synthesizing highly crystalline imine-based 3D covalent organic frameworks (COFs) that can meet the operational targets set by the US DOE. The design of the proposed 3D COF was inspired by the non-interpenetrated acs topology of the MOF NU-1501-Al which currently boasts the highest %H2 deliverable capacity. Computational simulations showed that the COF design can surpass its MOF counterpart. To achieve the desired COF, the key monomer with a trigonal prismatic geometry must be synthesized first. Of the two monomers, only the formyl bearing monomer TIAM was successfully synthesized and characterized by MS, NMR and single crystal data. However, attempts to form the target 3D COFs both failed due to lack of reaction time and heating, as evidenced from the FTIR and PXRD data. While the amine-bearing monomer was not synthesized, the key intermediate - the boronate ester of the aryl bearing the Boc-protected amine groups - was successfully synthesized; thus, it is a step closer to the synthesis of the amine-bearing monomer. While the attempts to synthesize a 3D COF failed, the successful synthesis of TIAM adds an additional type of monomer to the limited pool of available monomers for 3D COFs.</p>