UiO-66@SiO₂ core–shell microparticles as stationary phases for the separation of small organic molecules

Abstract

Composite particles containing the Zr-based metal-organic framework (MOF) UiO-66 were prepared using microwave-assisted solvothermal synthesis. Scanning electron microscopy, infrared spectroscopy, powder X-ray diffraction and nitrogen physisorption studies confirmed the deposition of 100-300 nm microporous particles with the UiO-66 topology on the surface of mesoporous 5 μm and non-porous 2.1 μm silica particles. The core-shell particles exhibited a unique flow-dependent separation selectivity (FDSS) effect which allows changes in both the retention and separation selectivity of small molecules by simple variation of the mobile phase flow rate under isocratic conditions. The impact of the loading of UiO-66 as well as the porosity of the underlying silica core (mesoporous and non-porous) on the FDSS effect was evaluated. The prepared adsorbents were also tested for the normal-phase (NP) and reversed-phase (RP) separation of xylene isomers, substituted benzenes and polyaromatic hydrocarbons (PAHs). Efficiencies of up to 32 400 plates per m (styrene, k 1.59) and 37 200 plates per m (anisole, k 2.90) were achieved under NP and RP modes, respectively. The results demonstrate the potential of novel MOF-based stationary phases for the separation of closely related compounds (e.g. positional isomers).

Emerging materials for sample preparation

“…The resulting material was washed to remove the undesired reagents and products, and the growth step was repeated a number of times until an MOF coating with the desired thickness was obtained. This method was applied to beads with a small particle size, and the so prepared MOF beads were subsequently used as stationary phases for LC .…”

Core–shell microspheres with porous nanostructured shells for liquid chromatography

“…However, only water‐stable MOFs are usually employed to produce silica‐MOF core–shell particles or other MOFs if the mobile phase contains no water. The MOFs mostly investigated in this regard include zeolitic imidazolate framework (ZIF‐8) , Universitetet i Oslo (UiO‐66) and Hong Kong University of Science and Technology (HKUST‐1) . This is likely because these MOFs can be readily formed on the silica surface with reasonable coverage and not too harsh conditions.…”

Ultra-Stable UiO-66 Involved Molecularly Imprinted Polymers for Specific and Sensitive Determination of Tyramine Based on Quartz Crystal Microbalance Technology

“…UiO-66 owned excellent chemical and thermal stability in water and can be well applied to the adsorption of various organic molecules [41]. The regulatable pore size of UiO-66 is one of its superior advantages as an adsorbent [42].…”

“…The morphology and uniform sizes of UiO-66 can be adjusted by adding acid [39] and controlling the concentrations of reagents and modulators [40]. UiO-66 owned excellent chemical and thermal stability in water and can be well applied to the adsorption of various organic molecules [41]. The regulatable pore size of UiO-66 is one of its superior advantages as an adsorbent [42].…”