Generating and optimizing the catalytic activity in UiO-66 for aerobic oxidation of alkenes by post-synthetic exchange Ti atoms combined with ligand substitution

Abstract

Generating and optimizing the catalytic activity in UiO-66 for aerobic oxidation of alkenes by post-synthetic exchange Ti atoms combined with ligand substitution.

Engineering catalytic sites for oxidation and condensation reactions using metal-organic frameworks or graphene-based materials

“…No significant differences in thermal stability were observed for both materials. XPS of the MIL-101(Cr)-X (X: H, NO2, SO3H and NH2) solids confirms the presence and types of the individual atoms expected for the corresponding MOF (C, O, Cr, N or S) in agreement with previous reports (Fig.S6-S9) 48. Specifically, it shows the presence of two individual components attributed to the aromatic carbons at 284.6 eV and carboxylate groups at 288.06 eV.…”

“…9). [46][47][48][49][50][51] Currently, thousands of MOFs have been prepared using transition metal ions, as well as alkaline earth metal ions as metal nodes coordinated with a large variety of organic ligands. 50,[52][53][54] Fig.…”

“…One of the MOF families that has attracted most interest for the development of several applications that include catalysis is denoted as MIL-101 (MIL stands for Materiaux of l'institut Lavoisier). 48 In MIL-101(Cr) the metal nodes are constituted by three trivalent transition metal cations (such as Cr 3+ or Fe 3+ ) connected to a central oxygen atom. The resulting nodes from Cr 3+ and Fe 3+ ions are (Cr3-µ3O) 7+ and (Fe3-µ3O) 7+ , respectively.…”

“…UiO-66(Zr)-X (X: H or NO2) solids have been prepared by adopting previously reported procedures. 48,54 Briefly, terephthalic acid or 2-nitroterephthalic acid (1 mmol) and ZrCl4 (1 mmol) were added to a Teflon autoclave containing DMF (3 mL). The autoclave was closed and heated at 220 ºC for 12 or 24 h for the preparation of UiO-66(Zr) and UiO-66(Zr)-NO2, respectively.…”

“…41 In a previous study, we have shown that MOFs can promote aerobic oxidations by activation of molecular oxygen and generation of hydroperoxyl and other reactive oxygen species. [45][46][47][48][49] Moreover it has been shown that the catalytic activity to promote aerobic oxidations is also strongly influenced by the presence of substituents on the linker. Inductive effects can increase the electronegativity of the linker and, as consequence, the oxidation potential of the nodal metal cation.…”