Fabrication of boronic acid-functionalized covalent organic framework for the selective adsorption of cis-diol-containing compounds

Abstract

In this work, we report a post-synthetic modification strategy to synthesize a boronic acid-functionalized porphyrin-based covalent organic framework (denoted as BA-COF) via the Suzuki-Miyaura cross-coupling reaction. Interestingly, BA-COF exhibits excellent selectivity in adsorbing cis-diol-containing compounds (CDC). The selective adsorption mechanism was addressed in detail, which is probably due to the boronate affinity from boronic acid group, hydrophilic interaction from the nitrogen-rich framework as well as "host–guest" interaction from the unique "trap" structure of porphyrin-based COF. The characterized results demonstrated its uniform morphology, large specific surface area, and excellent thermal stability. The adsorption kinetics demonstrated that the adenosine adsorption onto BA-COF conformed to the pseudo-second-order kinetic model and belonged to chemisorption. Based on the fitting of adsorption isotherms and thermodynamic analysis, the adenosine adsorption onto BA-COF was monomolecular layer adsorption and was a spontaneous endothermic reaction. Moreover, the reuse performance of BA-COF was investigated through consecutive adsorption–desorption cycle experiments. This work also demonstrates the potential of BA-COF for effective and selective adsorption of CDC in real sample.