Preparation of Magnetic Molecularly Imprinted COF-like Polymer for Diosmetin Separation from Natural Extracts

A magnetic molecularly imprinted covalent organic framework-like polymer (MMICP-DT/DAAQ) was prepared based on a multivariate synthetic strategy, utilizing 4,4′-diamino-terphenyl (DT)/2,6-diaminoanthraquinone (DAAQ) as functional monomers, 2,4,6-triformylphloroglucinol (TP) as the cross-linker, amino-functionalized magnetic nanoparticles (Fe3O4–NH2) as the support, and diosmetin as the template molecule. The microscopic structure and surface functional groups of MMICP-DT/DAAQ were further modified by adjusting the molar ratio of DT/DAAQ. The obtained MMICP-DT/DAAQ exhibited a high specific surface area (157.7 m2/g), favorable magnetic properties (30.6 emu/g), and a prominent adsorption capacity (106.5 mg/g). Meanwhile, the material also displayed excellent specific recognition ability (imprinting factor of 2.33) and satisfactory reusability with the retained adsorption capacity remaining at 69.5% of the initial value after nine cycles of adsorption and desorption. Notably, the adsorption capacity of MMICP-DT/DAAQ was determined by the imprinted-cavity complementarity rather than the specific surface area. Furthermore, the MMICP-DT/DAAQ, as a specific adsorbent, could extract and preliminarily purify diosmetin from various natural product extracts, with extraction efficiencies ranging from 63.8% to 77.4%. This work offers a design strategy for the preparation of MMICPs and also provides a simple and rapid method for preliminary purification of diosmetin across different matrices.