A Thiol-Functionalized UiO-67-Type Porous Single Crystal: Filling in the Synthetic Gap

Abstract

Thiol groups (−SH) offer versatile reactivity for functionalizing metal–organic frameworks, and yet thiol-equipped MOF solids remain underexplored due to synthetic challenges. Building on the recent breakthrough using benzyl mercaptan as the sulfur source and AlCl3 for uncovering the thiol function, we report on the thiol-equipped linker 3,3′-dimercaptobiphenyl-4,4′-dicarboxylic acid and its reaction with Zr­(IV) ions to form a UiO-67-type MOF solid with distinct functionalities. The thiol-equipped UiO-67 scaffold shows substantial stability toward oxidation, e.g., it can be treated with 30% H2O2 to afford oxidation of the thiol to the strongly acidic sulfonic function while maintaining the ordered porous MOF structure. The thiol groups also effectively take up palladium­(II) ions from solutions to allow for comparative studies on catalytic activities and to help elucidate how the spatial configuration of the thiol groups can be engineered to impact the performance of heterogeneous catalysis in the solid state. Comparative studies on the stability in the solventless (activated) state also help to highlight the steric factor in stabilizing UiO-67-type frameworks.

Reticular Chemistry for Ionic Liquid-Functionalized Metal–Organic Frameworks with High Selectivity for CO2

“…H 2 BPDC-MIMS is a derivative with one zwitterionic MIMS group substituted on the 2-position of 4,4′-biphenyl-dicarboxylate acid (H 2 BPDC) (Scheme ). Identical powder X-ray diffraction (PXRD) patterns of UiO-67-MIMS ( x ) ( x = 0.15, 0.20, 0.25, 0.30, 0.35, 0.50, 0.75, 1) indicate their same structure as that of the parent UiO-67 (Figure a). , So, the imidazolium sulfonate group (MIMS) and different BPDC-MIMS:BPDC ratios did not affect the framework structure of UiO-67-MIMS ( x ) due to the same linker length of H 2 BPDC-MIMS as that of H 2 BPDC …”

“…Identical powder X-ray diffraction (PXRD) patterns of UiO-67-MIMS (x) (x = 0.15, 0.20, 0.25, 0.30, 0.35, 0.50, 0.75, 1) indicate their same structure as that of the parent UiO-67 (Figure 1a). 19,30 So, the imidazolium sulfonate group (MIMS) and different BPDC-MIMS:BPDC ratios did not affect the framework structure of UiO-67-MIMS (x) due to the same linker length of H 2 BPDC-MIMS as that of H 2 BPDC. 31 The FT-IR spectra of UiO-67-MIMS (x) (Figure 1e) show the characteristic peaks of −SO 3 − of the MIMS group, with antisymmetric (ν a SO 3 − ) and symmetric stretching (ν s SO 3 − ) bands at 1180 cm −1 (ν a SO 3 − ), 1043 cm −1 (ν a SO 3 − ), and 877 cm −1 (ν s SO 3 − ).…”

Metal–Organic Frameworks Bearing Dense Alkyl Thiol for the Efficient Degradation and Concomitant Removal of Toxic Cr(VI)

“…It is well-documented that the thiol groups can not only form a Cr­(VI)–thiolate complex with Cr­(VI) under acidic conditions − but also further degrade Cr­(VI) and immobilize Cr­(III) via electrostatic interactions with sulfonic acid moieties resulting from the oxidation of thiol groups (as shown in Scheme A). , These greatly inspire us that an efficient solid adsorbent for toxic Cr­(VI) decontamination might be fabricated if we can integrate highly active and accessible thiol groups into the pore space of MOFs in advance. Unfortunately, the thiol-functionalized MOFs are often applied to the removal of Hg, while their other functions are neglected. − At present, most thiol-functionalized MOFs require a multistep ligand synthesis process, which is relatively complex and has a high cost. − Moreover, the sulfur atoms in the thiol-functionalized MOFs are usually connected with the benzene ring, and such a conjugation effect may enhance the stability of the S atom and weaken its reducibility. Therefore, the development of uncomplicated, easily accessible and highly active thiol-functionalized MOFs to effectively degrade Cr­(VI) and immobilize concomitant Cr­(III) is desirable.…”

High stability of ultra-small and isolated gold nanoparticles in metal–organic framework materials

“…Ru, Pt, Pd, Cu, Ni, Au). [12][13][14][15][16][17][18] MOFs are porous crystalline three-dimensional materials that can be synthesized with tailored pore sizes [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] and can even support internal functionalization, 25, [34][35][36][37][38][39] useful for applications such as pollutant sequestration, catalysis, photocatalysis, sensors, gas adsorption, fuel production, and biomedicine. [40][41][42][43][44][45][46] A few strategies have been proposed, such as impregnation of Au salt/alcohol mixtures with a gas-flow reduction, 36 direct incorporation of Au NPs during MOF synthesis, 47,48 or the growth of a MOF shell surrounding pre-existing Au NPs, [49][50][51] all of which suffer serious drawbacks such as contamination resulting from incomplete removal of metal precursor ligands or reductive agents.…”