High-Crystallinity Covalent Organic Framework Synthesized in Deep Eutectic Solvent: Potentially Effective Adsorbents Alternative to Macroporous Resin for Flavonoids

Abstract

A critical challenge in the enrichment of active ingredients in natural medicines is the design of adsorbents with high selectivity and adsorption capacity. Covalent organic frameworks (COFs), which have adjustable pores and high specific surface areas, could be effective as adsorbents for active ingredients. This study used an environmentally friendly deep eutectic solvent (DES) instead of organic solvents as the reaction solvent, and high-crystallinity COF-DES was successfully prepared. The COF-DES fabricated using 1,3,5-tris(4-aminophenyl)benzene and 2,5-dihydroxyterephthalaldehyde as building blocks showed good dispersibility, large surface area (444.56 m 2 •g −1 ), and suitable pore size (25.9 Å). Owing to its unique structure and functional group properties, COF-DES can prevent interferences from other compounds such as alkaloids, resulting in outstanding selective adsorption performance for flavonoids. Furthermore, under optimized adsorption conditions, the adsorption effects of the COF-DES on flavonoids were much better than those of the effects of macroporous resins, indicating the potential of the COF-DES as a selective adsorbent for flavonoids. Finally, a flavonoid-possessing rich natural medicine, Abelmoschus manihot (Linn.) Medicus flower, was used as a sample to study the application potential of the COF-DES. The results showed that the COF-DES had good adsorption and selection capability for flavonoids in actual samples. Moreover, compared with solid-phase extraction (SPE) columns based on macroporous resins, a COF-DES based SPE column showed superior adsorption performance for an actual complex sample, indicating the potential to COF-DES as an effective adsorbent alternative to macroporous resins. Additionally, the COF-DES had great commercial value as an adsorbent for SPE flavonoid columns.

Design Strategy and Application of Deep Eutectic Solvents for Green Synthesis of Nanomaterials

“…The as-prepared TpPa-COOH had open channels and exhibited good porosity and crystallinity under the low vapor pressure of DESs. Recently, Gao and coworkers described COF-DES inferred from 1,3,5-tris(4-aminophenyl)benzene and 2,5-dihydroxyterephthalaldehyde ( Figure 3 ) [ 108 ]. The DES has been used as a reaction medium instead of organic solvents to adjust pores and specific regions with high crystallinity.…”

High‐Affinity Adsorbent with Honeycomb Structure for Efficient Acteoside Separation

“…[11] Among them, adsorption method is widely used for adsorption and separation of bioactive components from natural production because of its high efficiency, reusable, lowenergy consumption etc. [12] For example, Li et al [13] synthesized rosin-based polymer microspheres, which used ethylene glycol maleic rosin acid acrylate as crosslinking agent and methacrylic acid (MAA) as functional monomer to adsorb berberine hydrochloride (BBH) in Coptidis rhizoma. This cross-linking agent reduced the secondary pollution of organic reagent adsorption.…”

One-Pot Synthesis of Deep Eutectic Solvents Containing Three-Dimensional Polymeric Materials with Excellent Catalytic Activity in the Knoevenagel Condensation Reaction

“…At the same time, we reported a new carboxyl-functionalized 2D COF synthesized in DESs for removing organic dyes from wastewater . Xia and Gao et al synthesized a high-crystallinity COF behaving as an effective adsorbent for flavonoids . However, not only the type and amount of POPs synthesized in DESs but also the subsequent applications of POPs were limited.…”

“…33 Xia and Gao et al synthesized a high-crystallinity COF behaving as an effective adsorbent for flavonoids. 34 DESs were loaded in the extended networks of the assynthesized 3D polymers (termed as TAM-BPA-DESs); moreover, the catalytic activity of the DESs-loaded polymeric materials in the Knoevenagel condensation reaction was revealed.…”