title: Visible light-harvesting trans bis(alkylphosphine) platinum(II)-alkynyl complexes showing long-lived triplet excited states as triplet photosensitizers for triplet-triplet annihilation upconversion.
abstract: Symmetric and asymmetric linear trans-bis(tributylphosphine) Pt(II) bis(acetylide) complexes with functionalized aryl alkynyl ligands (coumarin, naphthalimide and phenyl acetylides) were prepared, which show enhanced absorption in the visible region (molar absorption coefficients up to 76,800 M(-1) cm(-1) at 459 nm) and long-lived triplet excited states (up to 139.9 μs). At room temperature, the naphthalimide acetylide-phenyl acetylide complex (Pt-4) shows dual emission (fluorescence-phosphorescence), whereas other complexes show only fluorescence emission. The triplet excited states of the complexes were studied with nanosecond time-resolved transient difference absorption spectroscopy and DFT calculations on the spin density surface. The complexes were used as triplet photosensitizers for ratiometric O2 sensing, as well as triplet-triplet annihilation (TTA) upconversion (upconversion quantum yield up to 27.2%). The TTA upconversion of the complexes requires triplet acceptors with different T1 state energy levels and was studied with nanosecond time-resolved emission spectroscopy. Our results are useful for designing new Pt(II) complexes that show strong absorption of visible light and long-lived triplet excited states, as well as for the application of these complexes as triplet photosensitizers for O2 sensing, photocatalysis and TTA upconversion.
authors: State Key Laboratory of Fine Chemicals, School of Chemical Engineering, Dalian University of Technology, E 208 Western Compus, 2 Ling-Gong Road, Dalian 116012, P. R. China.
authors: Lianlian
authors: L
authors: Liu
authors: Dandan
authors: D
authors: Huang
authors: Sylvia M
authors: SM
authors: Draper
authors: Xiuyu
authors: X
authors: Yi
authors: Wanhua
authors: W
authors: Wu
authors: Jianzhang
authors: J
authors: Zhao