Supramolecular Engineering of Discrete Pt(II)···Pt(II) Interactions for Visible-Light Photocatalysis

Visible-light photosensitizers have emerged as a sustainable and environmentally friendly medium for organic transformation. Herein, we have developed a supramolecular strategy for manipulating visible-light photosensitization and photocatalytic efficiencies. With the elaborate manipulation of aggregated Pt­(II)···Pt­(II) interactions, the discrete tetranuclear Pt complexes not only show high binding affinity (<i>K</i>_a ∼ 10⁶ M^–1) but also feature bathochromic-shifted metal–metal-to-ligand charge transfer transitions. Both factors are crucial for their ¹O₂ generation capability upon low-energy visible-light irradiation (λ ≥ 590 nm). More interestingly, when a terpyridine moiety is embedded in the structure of a supramolecular photosensitizer, breakup of tetranuclear Pt­(II)···Pt­(II) complexation can be realized upon addition of Zn­(OTf)₂. As a consequence, photo-oxidation of a secondary amine to the corresponding imine can be deactivated and reactivated, via the sequential addition of Zn­(OTf)₂ and unsubstituted terpyridine as the competitive ligand. Hence, the current study proves that intelligent visible-light photocatalysts can be achieved via rational supramolecular design

Mechanical Activation of Platinum–Acetylide Complex for Olefin Hydrosilylation

Harnessing mechanical forces to activate latent catalysts has emerged as a novel approach to control the catalytic reactions in organic syntheses and polymerization processes. However, using polymer mechanochemistry to activate platinum-based catalysts, a class of important organometallic catalysts in industry, has not been demonstrated so far. Here we show that the platinum–acetylide complex is mechanoresponsive and can be incorporated into a polymer backbone to form a new mechanophore. The mechanically induced chain scission was demonstrated to be able to release catalytically active platinum species which could catalyze the olefin hydrosilylation process. Various control experiments were conducted to confirm that the chain scission and catalytic reaction were originated from the ultrasound-induced dissociation of platinum–acetylide complex. This work further exemplifies the utilization of organometallic complexes in design and synthesis of latent catalysts for mechanocatalysis and development of self-healing materials based on silicone polymers