Preparation of a pinoresinol diglucoside imprinted polymer using metal organic frame as the matrix for extracting target compound from Eucommia ulmoides

Fabrication of a post-synthesis imprint modification method for metal-organic frameworks in order to improve its selectivity in the field of separation and analysis is of great interest. For this purpose, a pinoresinol diglucoside (PDG) imprinted polymer was attempted to graft on the surface of metal-organic frameworks MIL-101 to produce a new composite material named MIPs@ED-MIL-101. This modification procedure was monitored by using X-Ray Diffraction, fourier transforms infrared spectroscopy and scanning electron microscopy in the crystal structure, chemical groups and particles topography, respectively. Adsorption kinetics and thermodynamics behavior, rebinding selectivity and applicability in solid-phase extraction for this new material obtained were evaluated. The kinetics test indicated this composite material improved adsorption dynamics relative to the MIL-101, with a 28.6% decrease in adsorption equilibrium time. The adsorption capacity for the MIPs@ED-MIL-101 toward PDG was shown higher than that for the MIL-101 and nonimprint-modified material NIPs@ED-MIL-101 at the same substrate concentration when adsorption was carried out at 298 K in acetonitrile-H2O mixed solution (1:1, V/V). Freundlich model can best fit the isotherm data for the MIPs@ED-MIL-101, indicating site heterogeneity in this composite material and mean adsorption energy of 19.60 kJ mol-1 obtained by Dubinin-Radushkevich model fitting might imply chemical adsorption the main rebinding process. In addition, this imprint composite material could selectively bind template and be utilized as the adsorbent in solid-phase extraction to capture target compound from plant crude extract. This new material can also be reused many times with a slight decrease in adsorption capacity.

Automated summary

A post-synthesis imprint modification method was developed for metal-organic frameworks to improve selectivity in separation and analysis. The PDG imprinted polymer was successfully grafted onto the MIL-101 surface to create the MIPs@ED-MIL-101 composite material, which showed enhanced adsorption capacity and kinetics compared to non-imprinted materials. The composite material exhibited site heterogeneity and chemical adsorption as the main rebinding process, making it suitable for solid-phase extraction and selective binding of target compounds.