Cuprous Cluster-Based Coordination Sheets as Photocatalytic Regulators to Activate Oxygen, Benzoquinone, and Thianthrenium Salts

Abstract

Cuprous clusters are well known for their important fluorescent properties and tunable redox behavior, but the coordinated protecting groups restrict their application in photocatalysis, in particular, the inner-sphere activation of substrates. By modifying fluorescent cuprous clusters with terminal iodides into two-dimensional coordination sheets, we report a photocatalytic regulator to synergistically combine electron transfer and energy transfer for the oxidative coupling of benzoquinone and terminal alkynes. Under visible light irradiation, the well-modified excited state of the cuprous clusters in the coordination sheets reduces benzoquinones to generate aoxy radicals through electron transfer and activates oxygen through energy transfer. The aoxy radicals interact with copper-coordinated phenylacetylene to form an active intermediate, which is further oxidized by the in situ formed active oxygen species and aryl ketones are obtained. The warranted potential of the excited coordination sheets enables the reductive activation of thianthrenium salts as radical precursors, facilitating radical capture and further C−N coupling via an inner-sphere activation mechanism. The new catalytic approach optimizes the redox properties and excited-state lifetime, shortens the electron transfer steps, and promotes the potential collision of a low concentration of active species in tandem catalytic cycles, thus paving a new way to develop ecologically benign, cost-effective, multipurpose, and flexible catalytic systems.

Ligand-regulated metal–organic frameworks for synergistic photoredox and nickel catalysis

“…4d and S23†). 73 These experimental results indicate that these crystals may undergo in situ exfoliation to form the nanosheets during the visible-light-driven catalysis. 74 The in situ exfoliation was supposed to be the breaking of the weak interactions by the mechanical shearing forces during stirring.…”

Anthraquinone-Based Metal–Organic Frameworks as a Bifunctional Photocatalyst for C–H Activation

“…72,73 Meanwhile, the in situ exfoliated nanosheet from the crystal blocks of Co−AQ could be easily observed using SEM and TEM (Figure S12). 74 In addition, both the light on−off experiments under alternating periods of irradiation and darkness (Figure 4d) and the quantum yield (Φ = 4.60%) of the photochemical reaction (Figure S13) confirmed that the radical chain mechanism in the oxidation turned out not to be predominant. 75,76 Meanwhile, the almost linear dependency of the yield on the irradiation power and the double ratio of k F to k H could rule out the mechanism of the overall two-photon excitation process, suggesting that this photocatalytic system parallelly absorbed two photons to accomplish the oxidation reaction (Figure 4e,f).…”

Controlled Partial Linker Thermolysis in Metal‐Organic Framework UiO‐66‐NH2 to Give a Single‐Site Copper Photocatalyst for the Functionalization of Terminal Alkynes

“…The resulting radical of THF further interacts with Cu‐acetylide intermediate to furnish the product. Similarly, the photoreduction of electron deficient benzoquinone generates a radical anion, [46] which interacts further with Cu‐acetylide intermediate to afford the product in reaction B . The formation of dipolar Cu‐complex from acetylide‐Cu intermediate and benzoquinone radical is indicated by spectrum studies (Figure S20).…”