Mixed Functionalization of Organic Ligands in UiO-66: A Tool to Design Metal–Organic Frameworks for Tailored Microextraction

Abstract

The mixed-ligand strategy was selected as an approach to tailor a metal–organic framework (MOF) with microextraction purposes. The strategy led to the synthesis of up to twelve UiO-66-based MOFs with different amounts of functionalized terephthalate ligands (H-bdc), including nitro (-NO2) and amino (-NH2) groups (NO2-bdc and NH2-bdc, respectively). Increases of 25% in ligands were used in each case, and different pore environments were thus obtained in the resulting crystals. Characterization of MOFs includes powder X-ray diffraction, infrared spectroscopy, and elemental analysis. The obtained MOFs with different degrees and natures of functionalization were tested as sorbents in a dispersive miniaturized solid-phase extraction (D-µSPE) method in combination with high-performance liquid chromatography (HPLC) and diode array detection (DAD), to evaluate the influence of mixed functionalization of the MOF on the analytical performance of the entire microextraction method. Eight organic pollutants of different natures were studied, using a concentration level of 5 µg· L−1 to mimic contaminated waters. Target pollutants included carbamazepine, 4-cumylphenol, benzophenone-3, 4-tert-octylphenol, 4-octylphenol, chrysene, indeno(1,2,3-cd)pyrene, and triclosan, as representatives of drugs, phenols, polycyclic aromatic hydrocarbons, and disinfectants. Structurally, they differ in size and some of them present polar groups able to form H-bond interactions, either as donors (-NH2) or acceptors (-NO2), permitting us to evaluate possible interactions between MOF pore functionalities and analytes’ groups. As a result, extraction efficiencies can reach values of up to 60%, despite employing a microextraction approach, with four main trends of behavior being observed, depending on the analyte and the MOF.

Building MOF Nanocomposites with Oxidized Graphitic Carbon Nitride Nanospheres: The Effect of Framework Geometry on the Structural Heterogeneity

“…The diversity of the metal centers and organic ligands leads to materials of particular crystallographic structure, texture, and chemistry. Due to these properties, MOFs have been tested for various applications such as gas separation/storage [4][5][6][7][8][9], purification [10][11][12], sensing [13][14][15][16], electrodes for batteries [17,18], microextraction [19,20], detoxification of chemical warfare agents [21][22][23][24][25], and heterogeneous catalysis [26][27][28].…”

Novel Approaches Utilizing Metal-Organic Framework Composites for the Extraction of Organic Compounds and Metal Traces from Fish and Seafood

“…As revealed from the TEM micrographs (Figure 9), the Fe 3 O 4 nanoparticles were successfully coated with a 10 nm in thickness silica layer. The XRD pattern of the Fe3O4@SiO2@UiO-66 core-shell microspheres revealed to match perfectly with UiO-66 [107,108]. As revealed from the TEM micrographs (Figure 9), the Fe3O4 nanoparticles were successfully coated with a 10 nm in thickness silica layer.…”

“…Under optimum conditions, extraction recovery ranged between 93.1-107.3%, however no potential sorbent reusability was reported [106]. The XRD pattern of the Fe 3 O 4 @SiO 2 @UiO-66 core-shell microspheres revealed to match perfectly with UiO-66 [107,108]. As revealed from the TEM micrographs (Figure 9), the Fe 3 O 4 nanoparticles were successfully coated with a 10 nm in thickness silica layer.…”

Hydrogenative Ring-Rearrangement of Furfural to Cyclopentanone over Pd/UiO-66-NO2 with Tunable Missing-Linker Defects

“…It was proposed that the Lewis acid sites provided by the unsaturated metal sites in Fe-MIL-100 played a crucial role in the furan ring-rearrangement to CPO [ 14 ]. Within the family of MOF materials, UiO-66, is a highly stable MOF [ 25 ]. The MOF is built up from [Zr 6 O 4 (OH) 4 (CO 2 ) 12 ] clusters linked with 1,4-benzenedicarboxylate ligands, featuring a porous cubic architecture.…”