关键词:
photocatalysis
photosensitizer
organometallic chemistry
Pt(II)center dot center dot center dot Pt(II) metal-metal bonds
supramolecular chemistry
摘要:
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)center dot center dot center dot Pt(II) interactions, the discrete tetranuclear Pt complexes not only show high binding affinity (K-a similar to 10(6) M-1) but also feature bathochromic-shifted metal metal-toligand charge transfer transitions. Both factors are crucial for their O-1(2) generation capability upon low-energy visible-light irradiation (lambda >= 590 nm). More interestingly, when a terpyridine moiety is embedded in the structure of a supramolecular photosensitizer, breakup of tetranuclear Pt(II)center dot center dot center dot 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.