A new green approach to synthesizing MIP-202@porous silica microspheres for positional isomer/enantiomer/hydrophilic separation

Abstract

Metal-organic frameworks (MOFs) with superior physicochemical properties have great potential for applications in chromatographic separation. However, currently popular methods for the synthesis of MOF-based silica composite materials usually require the use of harmful organic solvents and long-term high-temperature sealing reactions. In order to respond to the needs of green chromatography, it is urgent to develop a new green organic-solvent-free strategy for the synthesis of MOF@SiO2 composites. MIP-202 is a zirconium-MOF constructed from zirconium ion and L-aspartic acid, which features green synthesis as well as good hydrolytic stability and chemical stability. In this paper, SiO2-NH2 was first prepared in a hydrophilic deep eutectic solvent, and then an amino acid-based MOF material (MIP-202) was modified on the surface of the SiO2-NH2 in an aqueous solution to obtain a MIP-202@SiO2 composite material. The multi-mode separation performance of MIP-202@SiO2 as a promising liquid chromatographic stationary phase was particularly evaluated and the separation mechanisms were discussed. The MIP-202@SiO2 column exhibited excellent separation ability for aromatic positional isomers. In addition, chiral enantiomers and hydrophilic analytes were also satisfactorily detected and separated. This work provides a new approach for the facile synthesis of MOF-based liquid chromatographic separation material by using green deep eutectic solvent and water as the reaction media.