Turning on Visible-Light Photocatalytic C−H Oxidation over Metal–Organic Frameworks by Introducing Metal-to-Cluster Charge Transfer

Abstract

The tailorable structure and electronic structure of metal−organic frameworks (MOFs) greatly facilitate their modulated light harvesting, redox power, and consequently photocatalysis. Herein, a representative MOF, UiO-66, was furnished by installing Fe 3+ onto the Zr-oxo clusters, to give Fe-UiO-66, which features extended visible light harvesting, based on metal-to-cluster charge transfer (MCCT). The Fe-UiO-66 with unique electronic structure and strong oxidizing power exhibits visible light-driven water oxidation, which is impossible for pristine UiO-66. More strikingly, under visible irradiation, the generated holes over Fe-UiO-66 are able to exclusively convert H 2 O to hydroxide radicals, initiating and driving the activation of stubborn C-H bond, such as toluene oxidation. The electrons reduce O 2 to O 2•radicals that further promote the oxidation reaction. The related catalytic mechanism and the structure−activity relationship have been investigated in detail. As far as we know, this is not only an unprecedented report on activating "inert" MOFs for photocatalytic C-H activation but also the first work on extended light harvesting and enhanced photocatalysis for MOFs by introducing an MCCT process.

Precise Construction of Stable Bimetallic Metal–Organic Frameworks with Single-Site Ti(IV) Incorporation in Nodes for Efficient Photocatalytic Oxygen Evolution

“…22,26 Recent studies further demonstrate the capabilities of heterometallic clusters as the nodes of multivariate MOFs for heterogeneous catalysis. [27][28][29][30] These findings suggest it highly promising to achieve both stability and reactivity of Co-MOF photocatalysts by introducing proper high-valent cations into Co(II) clusters as heterometallic nodes. Nevertheless, such Co-MOFs have been rarely reported so far, 31 mostly due to the challenging fabrications tending toward the mixtures of monometallic MOFs or incomplete substitutions in the metal nodes.…”

Cationic Covalent‐Organic Framework as Efficient Redox Motor for High‐Performance Lithium–Sulfur Batteries

“…[28][29][30][31][32][33][34] However, even the carbon materials with good electrical conductivity could facilitate the transformation of the electrons and power the redox reaction in Li-S batteries, the vast majority of common carbon materials are amorphous and structurally uncertain, resulting in uneven characters of the materials and unclear mechanism of the interaction between host materials and sulfur. Nowadays, crystalline metal-organic frameworks (MOFs) with precise structure, [35,36] diverse species, [37][38][39][40][41] and adjustable aperture size [42] have been utilized as the potential cathode host for Li-S batteries. [17,43] MOFs with open metal sites can anchor the soluble PSs and thus suppress the shuttle effects, endowing the MOF-based Li-S batteries with high specific capacity and satisfactory cycling stability.…”

Synthesis and Photocatalytic Properties of Titanium‐Porphyrinic Aerogels

“…In addition, in view of the anionic nature of 1.5 wt %‐TPA, the diffusion of electron‐rich substrates into its pores should be more difficult than that of bare benzylamine, and the corresponding reaction can therefore be retarded. The related mechanism was probed by conducting the reaction in the presence of 2‐methylfuran as a 1 O 2 scavenger, [27] 2,6‐di‐ t ‐butyl‐4‐methylphenol as an O 2 .− scavenger, [26] and phenol as a hole scavenger [9b] . The yield of N ‐benzylidenebenzylamine decreased to 16 % in the presence of 1 O 2 or .…”