Mechanochemical synthesis of highly crystalline boroxine-linked covalent organic frameworks (COFs) via trimethylboroxine Ehsan Hamzehpoor 1 , Farshid Effaty 1,2 , Xavier Ottenwaelder 2 , Tomislav Friščić 1 and Dmytro F. Perepichka 1 1 Department of Chemistry, McGill University, Canada, 2 Department of Chemistry and Biochemistry, Concordia University, Canada Boroxine is one of the first and most studied synthons of covalent organic frameworks (COFs). Despite their wide application in the design of functional COFs over the last 15 years, their synthesis still relies on the original Yaghi’s solvothermal condensation of boronic acids with itself,1 some of which are difficult to prepare, poorly soluble, or unstable in the presence of water at elevated temperatures. Inspired by our recent modification to the original solvothermal reaction,2 we propose a liquid-assisted grinding (LAG) mechanochemical approach to boroxine COFs using trimethylboroxine (TMB) as the dehydrating agent. Using this approach highly crystalline COFs were synthesized at room temperature with quantitative yields in less than one hour and in the absence of bulk solvent, The liquid additive used in liquid-assisted grinding proves to be highly versatile showing high crystallinity in a different range of solvents which is not possible in the solvothermal method.
References 1. A. P. Côté, A. I. Benin, N. W. Ockwig, M. O’Keeffe, A. J. Matzger, O. M. Yaghi, Science, 2005, 310, 1166–1170. 2. E. Hamzehpoor, A. Jonderian, E. McCalla, D. F. Perepichka, J. Am. Chem. Soc. 2021, 143, 13274–13280.
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