The Redox Coupling Effect in a Photocatalytic Ru^II‐Pd^II Cage with TTF Guest as Electron Relay Mediator for Visible‐Light Hydrogen‐Evolving Promotion

Abstract

A nanocage coupling effect from a redox RuII‐PdII metal–organic cage (MOC‐16) is demonstrated for efficient photochemical H2 production by virtue of redox–guest modulation of the photo‐induced electron transfer (PET) process. Through coupling with photoredox cycle of MOC‐16, tetrathiafulvalene (TTF) guests act as electron relay mediator to improve the overall electron transfer efficiency in the host–guest system in a long‐time scale, leading to significant promotion of visible‐light driven H2 evolution. By contrast, the presence of larger TTF‐derivatives in bulk solution without host–guest interactions results in interference with PET process of MOC‐16, leading to inefficient H2 evolution. Such interaction provides an example to understand the interplay between the redox‐active nanocage and guest for optimization of redox events and photocatalytic activities in a confined chemical nanoenvironment.

Host–Guest-Induced Electron Transfer Triggers Radical-Cation Catalysis

“…The use of encapsulated transition metal catalysts, as exemplified by Toste, Raymond, and Bergman, can be viewed as a form of biomimetic holocatalysis. While common in nature, manipulation of redox properties using synthetic hosts is much less common, even less so for catalytic applications . Herein we show that the binding of several commercially available quinones by a simple coordination cage generates catalytic activity not inherent in either component.…”

Perylene Diimide-Based Multicomponent Metallacages as Photosensitizers for Visible Light-Driven Photocatalytic Oxidation Reaction

“…[12][13][14][15][16][17][18][19] This strategy takes the highly directional metal-coordination bonds to prepare SCCs spontaneously and endows the SCCs with high structural and functional diversity. [20][21][22][23][24][25][26][27][28] Especially, the preparation of photosensitizers using this method not only avoids their self-aggregation through the formation of geometric structures, but also facilitates the intersystem crossing owing to the introduction of heavy metal atoms, giving high 1 O 2 generation ability and photostability. [29][30][31][32][33][34] Moreover, different buliding blocks capable of generating 1 O 2 can be integrated into a single metallacage.…”

Modifying electron injection kinetics for selective photoreduction of nitroarenes into cyclic and asymmetric azo compounds

“…Recent advances have demonstrated that dye-loaded redox-active capsules are capable of enhancing the stability of charge separation states 13 , via the fast pseudo-intramolecular electron transfer from the excited state of dyes to the metal ions, for light-driven hydrogen evolution and hydrogenation reactions using the in situ formed green H-source 14 , 15 . We envisioned that fine tuning the entry behavior of electron donors into the hosts would balance the kinetics between electron injection and substrate reduction, generating unique selectivity different from the reported abiotic manifolds 16 , One of the important catalytically relevant but still sluggish conversions is selective reduction of nitroarenes into azo products 17 – 20 , due to the inherent complexity of the nitro reduction processes 21 – 24 and the distinctive application of azo compounds in the areas of liquid crystals, photochemical switches and sensitive shuttles (Fig.…”