Synthesis of functional ionic liquid modified silica and its excellent performance in selective separation of artemisinin/artemisitene

Abstract

To ensure the safety of drugs in clinical use and avoid side effects, the impurity content should be strictly controlled. Artemisitene (ARE) has quite similar structure to that of the antimalarial artemisinin, and thus is difficult to be removed from the target drug. The traditional column chromatography method to purify artemisinin has low separation efficiency and needs lots of organic solvents. In this work, functional ionic liquid (IL), 1-(trimethoxysilyl) benzene-3-vinylimidazolium chloride, modified silica materials were synthesized. Composition of the functional materials were characterized by energy dispersive spectroscopy, FT-IR, and X-ray photoelectron spectroscopy. It was indicated that the designed ionic liquid was successfully grafted onto SiO2. Adsorption capacity of the prepared ionic liquid-based material for artemisinin and artemisitene was evaluated, and it was demonstrated that adsorption of ARE by the functional material was a quick process, and the adsorption kinetics followed the Elovich Model. This kind of IL@SiO2 material exhibited excellent performance in selective separation of artemisitene from artemisinin. Mechanism exploration by spectroscopic analysis revealed that π-π conjugated interactions between the unsaturated bond (the C=C bond and aromatic ring) in the ionic liquid and artemisitene enhanced the molecular recognition capability of IL@SiO2 for ARE, resulting in selective separation of these two structurally analogues.