A Practice of Reticular Chemistry: Construction of a Robust Mesoporous Palladium Metal–Organic Framework via Metal Metathesis

Abstract

Constructing stable palladium(II)-based metal−organic frameworks (MOFs) would unlock more opportunities for MOF chemistry, particularly toward applications in catalysis. However, their availability is limited by synthetic challenges due to the inertness of the Pd−ligand coordination bond, as well as the strong tendency of the Pd(II) source to be reduced under typical solvothermal conditions. Under the guidance of reticular chemistry, herein, we present the first example of an azolate Pd-MOF, BUT-33(Pd), obtained via a deuterated solvent-assisted metal metathesis. BUT-33(Pd) retains the underlying sodalite network and mesoporosity of the template BUT-33(Ni) and shows excellent chemical stability (resistance to an 8 M NaOH aqueous solution). With rich Pd(II) sites in the atomically precise distribution, it also demonstrates good performances as a heterogeneous Pd(II) catalyst in a wide application scope, including Suzuki/Heck coupling reactions and photocatalytic CO 2 reduction to CH 4 . This work highlights a feasible approach to reticularly construct noble metal based MOFs via metal metathesis, in which various merits, including high chemical stability, large pores, and tunable functions, have been integrated for addressing challenging tasks.

Structural Evolution of MOF-Derived RuCo, A General Catalyst for the Guerbet Reaction

“…Prior examples of the coordination of two donor ligands to the ruthenium center with transfer of the chloride ligand to a different metal center provides support for our assignment of Ru 2 Cl 4 (CO) 6 @MFU-1 as the structure shown in Figure f (Table S15, Figure S19). Because incorporation of a second-row transition metal into a MOF SBU is highly unusual, however, further studies are needed to conclusively establish the coordination geometry around ruthenium in Ru 2 Cl 4 (CO) 6 @MFU-1. , …”

“…Because incorporation of a second-row transition metal into a MOF SBU is highly unusual, however, further studies are needed to conclusively establish the coordination geometry around ruthenium in Ru 2 Cl 4 (CO) 6 @MFU-1. 69,70 Formation of the Active Catalyst under the Reaction Conditions. The reaction conditions used for the Guerbet reaction are both basic and reductive, with H 2 being evolved in the dehydrogenation of the alcohol substrate during the first step of the Guerbet mechanism.…”

A switchable sensor and scavenger: detection and removal of fluorinated chemical species by a luminescent metal–organic framework

“… 40 For example, Li and co-workers developed a series of BUT-32 and BUT-33 (BUT = Beijing University of Technology) MOFs with remarkable water stability as a result of combination of soft base pyrazole and soft acid Ni 2+ . 41,42 By use of hard acid (Hf 4+ and Zr 4+ ) and hard base carboxylate ligands PCN MOFs developed by Zhou and co-workers also demonstrate high water and acid/base stability. 43–45 …”

Boosting Electrocatalytic Oxygen Evolution: Superhydrophilic/Superaerophobic Hierarchical Nanoneedle/Microflower Arrays of CexCo3–xO4 with Oxygen Vacancies

“…A lot of alternative OER catalysts based on earth-abundant metals (e.g., Fe, Co, Ni, and Mn), including phosphates, − chalcogenides, − nitrides, , and boride, have been brought up, but most of the above catalysts are thermodynamically less stable than metal oxides in strongly oxidative environments, which are usually reconstructed to form the real active species of metal oxides/(oxy)­hydroxides during the OER measurement. ,, Among metal oxides, Co 3 O 4 has attracted tremendous attention as an OER catalyst for its excellent catalytic activity and electrochemical durability in alkaline electrolytes, but its catalytic performance is inhibited by low active site exposure, poor conductivity, and unsuited adsorption strength for intermediates. − Several strategies have been utilized to optimize the catalytic activity of metal oxides, such as incorporating foreign elements and oxygen defects to modulate electronic structure − and regulating the morphology of catalysts with larger surface area to fully expose active sites. − Recently, rare-earth elements (like Ce, Pr, and La) have made great progress in the fields of sensors, , phosphors, and catalysts. − Among rare-earth elements, Ce has unique oxophilic properties, which can modify the local electronic environment and facilitate the subsequent series of oxygen-containing intermediate adsorption and reaction conversion to accelerate the generation of oxygen. , Benefiting from the flexible transition between Ce 3+ and Ce 4+ , Ce can modify local chemical binding to increase oxygen vacancy concentration for improving the electrical conductivity of metal oxides. , In addition, Ce ion can be regarded as a hard Lewis acid for the special property of easy oxyphilic coordination with flexible and high coordination number, which makes it easy to bond with some hard oxygen ligands (like OH – ). Therefore, Ce ion can be regarded as a buffer to hinder the attack from alkaline solution, playing a role in regulating the crystal growth and overall morphology of metal oxides. ,, …”