Evidence for enhanced dipolar interactions between Pt centers in binuclear phosphorescent complexes

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• 作者：Xiangfei Qi ; P.I. Djurovich ; N.C. Giebink ; M.E. Thompson ; S.R. Forrest
• 关键词：Autoimmunity ; EAE/MS ; Tolerance ; T cell receptors ; Peyer's patch
• 刊名：Chemical Physics Letters
• 出版年：2008
• 期刊代码：7_00092614
• 类别：ph
• 出版时间：17 June 2008
• 卷：458
• 期：4-6
• 页码：323-328
• 文件大小：668 K

摘要

Transient studies are used to examine the radiative decay dynamics in a series of phosphorescent platinum binuclear complexes. The complexes studied consist of square planar (2-(4′,6′-difluorophenyl)pyridinato-N,C^2′)Pt units bridged by either pyrazole or thiopyridine ligands. We observe an increase in radiative lifetime as temperature is reduced from 300 K to 4 K when the binuclear complexes, named ng>1ng>, ng>2ng> and ng>3ng> with Pt–Pt spacings 3.19 Å, 3.05 Å, and 2.83 Å, respectively, are doped into a p-bis(triphenylsilyly)benzene wide energy gap host. The lifetimes for ng>1ng>, ng>2ng> and ng>3ng> are τ = 6.3 ± 0.1 μs, τ = 2.3 ± 0.1 μs, and τ = 2.0 ± 0.1 μs at T = 295 K, respectively. At T = 4 K, those values increase to τ = 8.6 ± 0.1 μs, τ = 14.4 ± 0.1 μs, and τ = 17.0 ± 0.1 μs, suggesting that the neighboring heavy metal centers in compounds ng>2ng> and ng>3ng> have significant orbital overlap. A three-level zero-field splitting model yields the lowest triplet energy splittings of 28 ± 3 cm⁻¹, 142 ± 9 cm⁻¹, and 113 ± 10 cm⁻¹ for compounds ng>1ng>, ng>2ng> and ng>3ng>, respectively.