Atom Transfer Radical Polymerization Preparation and Photophysical Properties of Polypyridylruthenium Derivatized Polystyrenes

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• 作者：Zhen Fang ; Akitaka Ito ; Shahar Keinan ; Zuofeng Chen ; Zoe Watson ; Jason Rochette ; Yosuke Kanai ; Darlene Taylor ; Kirk S. Schanze ; Thomas J. Meyer
• 刊名：Inorganic Chemistry
• 出版年：2013
• 出版时间：August 5, 2013
• 年：2013
• 卷：52
• 期：15
• 页码：8511-8520
• 全文大小：510K
• 年卷期：v.52,no.15(August 5, 2013)
• ISSN：1520-510X

文摘

A ruthenium containing polymer featuring a short carbonyl-amino-methylene linker has been prepared by atom transfer radical polymerization (ATRP). The polymer was derived from ATRP of the N-hydroxysuccinimide (NHS) derivative of p-vinylbenzoic acid, followed by an amide coupling reaction of the NHS-polystyrene with Ru(II) complexes derivatized with aminomethyl groups (i.e., [Ru(bpy)₂(CH₃-bpy-CH₂NH₂)]²⁺ where bpy is 2,2鈥?bipyridine, and CH₃-bpy-CH₂NH₂ is 4-methyl-4鈥?aminomethyl-2,2鈥?bipyridine). The Ru-functionalized polymer structure was confirmed by using nuclear magnetic resonance and infrared spectroscopy, and the results suggest that a high loading ratio of polypyridylruthenium chromophores on the polystyrene backbone was achieved. The photophysical properties of the polymer were characterized in solution and in rigid ethylene glycol glasses. In solution, emission quantum yield and lifetime studies reveal that the polymer鈥檚 metal-to-ligand charge transfer (MLCT) excited states are quenched relative to a model Ru complex chromophore. In rigid media, the MLCT-ground state band gap and lifetime are both increased relative to solution with time-resolved emission measurements revealing fast energy transfer hopping within the polymer. Molecular dynamics studies of the polymer synthesized here as well as similar model systems with various spatial arrangements of the pendant Ru complex chromophores suggest that the carbonyl-amino-methylene linker probed in our target polymer provides shorter Ru鈥揜u nearest-neighbor distances leading to an increased Ru*-Ru energy hopping rate, compared to those with longer linkers in counterpart polymers.