(384d) Scalable Routes to Synthesis and Processing of Imine-Linked Cofs | AIChE

(384d) Scalable Routes to Synthesis and Processing of Imine-Linked Cofs

Authors 

Verduzco, R. - Presenter, Rice University
Zhu, D., Rice Univeristy
Covalent Organic Frameworks (COFs) are crystalline, porous organic materials with promise for applications including catalysis, energy storage, electronics, gas storage, water treatment, and drug delivery. However, challenges in both synthesis and processing limit their development for various applications. Conventional solvothermal synthesis approaches require elevated temperatures, inert environments, and long reaction times and produce insoluble powders that are difficult to process. In this presentation, we present novel synthesis and processing strategies that greatly facilitate the development and incorporation of COFs for various applications. First, we report that transition metal nitrates catalyze the rapid synthesis of imine COFs at ambient conditions. We first tested a series of transition metal for the synthesis of a model COF and found that all transition metal nitrates tested produced crystalline COF product even in the presence of oxygen. Fe(NO3)3·9H2O was found to produce the most crystalline product, and crystalline COF could be produced within 10 minutes by optimizing the catalyst loading. Fe(NO3)3·9H2O was further tested as a catalyst for 6 different COF targets varying in linker lengths, substituents, and stabilities, and it effectively catalyzed the synthesis of all imine COFs tested. This catalyst was also successful in the synthesis of 2D imine COFs with different geometries, 3D COFs, and azine-linked COFs. Next, we demonstrate a novel and simple approach to synthesize pure crystalline COF aerogels. In contrast to previously re-ported methods for fabricating COF foams and aerogels, our method does not require any additives that remain in the final COF or acids which can degrade or disrupt the COF crystallinity. In brief, our method involves using dimethyl sulfoxide (DMSO) as the reaction solvent and 6M acetic acid as the catalyst. We tested this solvent and catalyst combination for the synthesis of six different imine COFs. These macroscopic COF aerogels retain the shape of the reaction vial, feature hierarchical micropores and mesopores, and show excellent adsorption capacities. We demonstrate that these COFs could be easily effectively implemented in adsorption and decontamination applications. This work is significant because it provides a straightfor-ward and general route to produce macroscopic COF aero-gels, and our method will be of interest to those interested in developing COFs for membrane-based separations, energy storage applications, decontamination and remediation, and other applications which benefit from macroscopic and po-rous COF scaffolds. Altogether, these demonstrated approaches to COF synthesis and processing will significantly lower the barrier for the development of COFs for applications.