title: Coumarin phosphorescence observed with N^N Pt(II) bisacetylide complex and its applications for luminescent oxygen sensing and triplet-triplet-annihilation based upconversion.
abstract: A dbbpy platinum(II) bis(coumarin acetylide) complex (Pt-1, dbbpy = 4,4'-di-tert-butyl-2,2'-bipyridine) was prepared. Pt-1 shows intense absorption in the visible region (λ(abs) = 412 nm, ε = 3.23 × 10(4) M(-1) cm(-1)) compared to the model complex dbbpy Pt(II) bis(phenylacetylide) (Pt-2, λ(abs) = 424 nm, ε = 8.8 × 10(3) M(-1) cm(-1)). Room temperature phosphorescence was observed for Pt-1 ((3)IL, τ(P) = 2.52 μs, λ(em) = 624 nm, Φ(P) = 2.6%) and the emissive triplet excited state was assigned as mainly intraligand triplet excited state ((3)IL), proved by 77 K steady state emission, nanosecond time-resolved transient absorption spectroscopy and DFT calculations. Complex Pt-1 was used for phosphorescent oxygen sensing and the sensitivity (Stern-Volmer quenching constant K(SV) = 0.012 Torr(-1)) is 12-fold of the model complex Pt-2 (K(SV) = 0.001 Torr(-1)). Pt-1 was also used as triplet sensitizer for triplet-triplet-annihilation based upconversion, upconversion quantum yield Φ(UC) up to 14.1% was observed, vs. 8.9% for the model complex Pt-2.
authors.affiliation: State Key Laboratory of Fine Chemicals, School of Chemical Engineering, Dalian University of Technology, Dalian, 116024, PR China.
authors.forename: Haiyang
authors.initials: H
authors.lastname: Sun
authors.forename: Huimin
authors.initials: H
authors.lastname: Guo
authors.forename: Wenting
authors.initials: W
authors.lastname: Wu
authors.forename: Xin
authors.initials: X
authors.lastname: Liu
authors.forename: Jianzhang
authors.initials: J
authors.lastname: Zhao