Orderly MOF-Assembled Hybrid Monolithic Stationary Phases for Nano-Flow HPLC

Abstract

We report an approach that polymerizable handle-modified nanosized metal organic frameworks (MOFs) are used as independent monomers to be covalently organized by crosslinking molecules (CLMs) into an orderly MOF-assembled hybrid monolithic stationary phase, overcoming the respective problems of previously reported MOF-mixed or embedded stationary phases so far. It has a hierarchical micro-, meso-, and macropore structure throughout the monolithic matrix that is donated from MOF themselves, formed via CLM crosslinking in-between MOFs and expended by porogenic solvents, and a tunable surface chemistry derived inherently from MOFs, regulated by CLMs and initiated by the mobile phases as well. Such a pore structure and surface chemistry display multiplex interactions of sieving and electrostatic repulsion in addition to the polarity-based interactions that synergistically govern the partitioning way and degree of target molecules between the stationary and mobile phases, thus offering the ability to simultaneously separate small and large molecules during one chromatographic run on a nano-flow capillary high-performance liquid chromatography platform. A baseline mutual separation with the HETP and R s of, for example, 9.2 μm butylbenzene and 4.56 (butylbenzene and pentylbenzene), 7.9 μm (phenylalanine) and 3.50 (tryptophan and phenylalanine), and 7.0 μm (myoglobin) and 1.91 (bovine serum albumin and myoglobin) was achieved when UiO-66/NHmethacrylate was exemplified as a model of MOFs and 1,6-hexanediol dimethacrylate and stearyl methacrylate together as CLMs. Not limited to the MOFs and CLMs demonstrated here, other available MOFs and CLMs or newly designed and synthesized ones are expected to be used for constructing one's own desired monolithic stationary phases toward her/his particular purposes.

Recent trends on the implementation of reticular materials in column‐centered separations

“…The direct incorporation of MOFs in a polymer monolith has been improved by using the functional MOF linker 2‐aminoterephthalic acid [ 39 ] used for the synthesis of the MOF NH 2 ‐UiO‐66. The amino group present in the organic linker does not participate in the coordination process with Zr(IV) but remains available for postsynthetic modification.…”

Gold Nanoparticle-Decorated Porous Silica for Surface-Enhanced Raman Scattering-Based Detection of Trace Molecules in Liquid Phase

“…Monolith is a 3D porous structured material with micrometer- to nanometer-sized continuous interconnected fluidic channel networks. − As the traditional stationary phase in liquid chromatography, monolith not only has a unique characteristic of supporting the rapid permeation of the aqueous phase while offering short characteristic diffusion lengths, but also provides a high specific surface area and active sites for enhancing analyte–monolith interactions . Monolith has the potential advantage that the unique porous network provides a high surface area, resulting in much more active sites participating in Raman scattering.…”

Homomesoporous Metal–Organic Framework for High-Performance Electrochromatographic Separation

“…Up to now, a growing amount of research has focused on the huge potential of MOFs in chromatographic stationary phases including high-performance liquid chromatography, , gas chromatography, − and capillary electrochromatography (CEC). , However, since most of the previously reported MOF-based stationary phases only have microporous (<2 nm) structures, they usually suffer from critical issues such as high mass transfer resistance, limited available interaction sites, and inaccessibility of the internal space in MOFs, which place severe limitations on the electrochromatographic separation performance . To settle these problems, an alternative way is to augment the channel sizes of MOF-based stationary phases to the mesoporous range (2–50 nm). , In our previous study, the nanoscale hierarchically porous MOFs (NHP-MOFs)-based stationary phase, NHP-UiO-66, consisting of microporous and mesoporous structures, was explored for electrochromatographic separation with remarkably improved resolution and column efficiency, benefiting from the good mass transfer performance and abundant available interaction sites of NHP materials.…”