A nanocrystalline metal organic framework confined in the fibrous pores of core-shell silica particles for improved HPLC separation

A hybrid material was prepared from a metal-organic framework (MOF) and core-shell silica by using a kinetic controlling approach. The nanocrystalline MOF (HKUST-1) was prepared from 1,3,5-benzenetricarboxylate and copper(II) by tuning the reaction rate via the fraction of ethanol in the solvent. After the reaction rate was reduced to a certain degree, the pore surface would be well covered with Cu(II), which initiated the formation of a nanocrystalline HKUST-1. The resulting hybrid material was packed into a stainless-steel column (4.6 × 150 mm) and used as a stationary phase in high performance liquid chromatography. SiO 2 @ d SiO 2 -HKUST-1 combined the merits of the high separation performance of the core-shell particles and the unique selectivity of the HKUST-1 nanocrystals. A separation efficiency as high as almost 140,000 plates per meter was achieved for the model analyte styrene. The material was stable and exhibited a highly reproductivity. The relative standard deviations of column-to-column, intra-day, and inter-day reproducibility of the SiO 2 @ d SiO 2 -HKUST-1 packed columns for the retention time of styrene were 4.7%, 0.3%, and 0.4%, respectively. HKUST-1 nanocrystals were coated onto the porous surface of core-shell silica spheres under careful kinetic control. The resulting particles were packed into the column, and a separation performance of up to 140,000 plates per meter was achieved.