Sequential Modifications of Metal–Organic Layer Nodes for Highly Efficient Photocatalyzed Hydrogen Atom Transfer

Abstract

Herein, we report the synthesis of a bifunctional photocatalyst, Zr-OTf-EY, through sequential modifications of metal cluster nodes in a metal–organic layer (MOL). With eosin Y and strong Lewis acids on the nodes, Zr-OTf-EY catalyzes cross-coupling reactions between various C–H compounds and electron-deficient alkenes or azodicarboxylate to afford C–C and C–N coupling products, with turnover numbers of up to 1980. In Zr-OTf-EY-catalyzed reactions, Lewis acid sites bind the alkenes or azodicarboxylate to increase their local concentrations and electron deficiency for enhanced radical additions, while EY is stabilized by site isolation on the MOL to afford a long-lived catalyst for hydrogen atom transfer. The proximity between photostable EY sites and Lewis acids on the nodes of Zr-OTf-EY enhances the catalytic efficiency by approximately 400 times over the homogeneous counterpart in the cross-coupling reactions.

Two-Dimensional Sulfonate-Functionalized Metal–Organic Framework Membranes for Efficient Lithium-Ion Sieving

“…However, it requires both angstrom precision and ample active sites in the nanochannels for separating alkali metal and alkaline-earth metal ions of subnanometer size, which could be achieved by using MOFs. Typically, Zr-BTB (BTB = 1,3,5-(4-carboxylphenyl)-benzene) MOFs have been widely used in light-harvesting, catalyst, , and isomer separation . According to Pearson’s hard–soft acid base (HSAB) principle, the MOFs constructed by hard Lewis-acid (Zr 4+ ) and hard Lewis-base (carboxylates) processes are well water stabile, holding the potential to work in an aqueous environment.…”

“…First, we used the bottom-up approach to directly synthesize the ultrathin 2D Zr-BTB MOF nanosheets, between Zr IV salts and the H 3 BTB bridging ligands. Formic acid served as a saturated modulator to overcome high surface energy and suppress the growth along the vertical direction. , The six-connected Zr 6 secondary building units (SBUs) and the three-connected BTB ligands link to each other to form a 2D network with (3,6)-connected kagome dual (kgd) topology , (Figure b). Besides the connection with six carboxylate groups within the layer, the capping formate ions above and below the layer are unstable and can be removed by activation. , Then, a sulfonate-functionalized MOF (Zr-BTB/PSS) was synthesized by functionalizing Zr-BTB with sulfonate groups of PSS, forming a coordination bond , between terminal −SO 3 and the unsaturated Zr IV sites (Figure c, left).…”

Advances and Applications of Metal‐Organic Frameworks (MOFs) in Emerging Technologies: A Comprehensive Review

“…A bifunctional photocatalyst MOF, Zr‐OTf‐EY (EY = Eosin Y dye) wherein EY acts as a Lewis acid on metal cluster nodes in MOF underwent cross‐coupling catalytic reaction of C‐H compounds with electron‐deficient alkenes or azodicarboxylate, giving rise to C‐C and C‐N products with a TON (Turn‐over number) of 1980 ( Figure 4 a ). [ 129 ] The proximity between photoactive EY and nodes of MOF increased the catalytic performance ≈ 400 times. In this reaction, EY acted as a long‐lived catalyst for H atom transfer by stabilizing in the site isolation on the metal‐organic layer (MOL).…”

“…Reproduced with permission. [ 129 ] Copyright 2023, American Chemical Society. b) Polymolybdate‐based MOFs as highly active electrocatalysts for hydrogen generation from water.…”

Modulating Charge Transfer Pathways to Enhance Photocatalytic Performance of the Metal–Organic Layer Nanosheet

“…Recently, 2D MOF nanosheets, also named 2D metal–organic layers (MOLs), have attracted great research interest due to their outstanding physical and chemical properties, such as ultrathin layer thickness, high specific surface area, abundant unsaturated metal sites, tunable chemical composition, and recognizable surface atomic structure, which facilitates contact between reactants and active sites, rapid diffusion of reactants and products, and promotes rapid surface redox reactions in the photocatalysis process. – The reduced diffusion pathway from photogenerated carriers to reactants and the increased opportunity for contact between the reactant substrate and the active surface often lead to better catalytic activity of 2D MOF nanosheets than the corresponding 3D stacked structures. – The shortcomings of current research focus on how to expose more metal active sites and the lack of effective strategies to further modify the charge transfer pathways in 2D MOFs. The proper charge transfer pathways in 2D MOFs are very favorable for the generation of photogenerated electron–hole pairs, which are very favorable for SET and energy transfer (ET) of photocatalysts, such as promoting the generation of O 2 to reactive oxygen species.…”