T. Brietzke, T. Dietz, A. Kelling, U. Schilde, J. Bois, H. Kelm, M. Reh, M. Schmitz, T. Körzdörfer, S. Leimkühler, U. Wollenberger, H.-J. Krüger, H.-J. Holdt
The 1,6,7,12-Tetraazaperylene Bridging Ligand as an Electron Reservoir and Its Disulfonato Derivative as Redox Mediator in an Enzyme-Electrode Process
Chemistry - A European Journal 2017, 23, 15583
DOI: 10.1002/chem.201704226
The homodinuclear ruthenium(II) complex [{Ru(l-N₄Me₂)}₂(μ-tape)](PF₆)₄ {[1](PF₆)₄}(l-N₄Me₂=N,N′-dimethyl-2,11-diaza[3.3](2,6)-pyridinophane, tape=1,6,7,12-tetraazaperylene) can store one or two electrons in the energetically low-lying π* orbital of the bridging ligand tape. The corresponding singly and doubly reduced complexes [{Ru(l-N₄Me₂)}₂(μ-tape.−)](PF₆)₃ {[2](PF₆)₃} and [{Ru(l-N₄Me₂)}₂(μ-tape2−)](PF6)₂ {[3](PF₆)₂}, respectively, were electrochemically generated, successfully isolated and fully characterized by single-crystal X-ray crystallography, spectroscopic methods and magnetic susceptibility measurements. The singly reduced complex [2](PF₆)₃ contains the π-radical tape.− and the doubly reduced [3](PF₆)₂ the diamagnetic dianion tape2− as bridging ligand, respectively. Nucleophilic aromatic substitution at the bridging tape in [1]4+ by two sulfite units gave the complex [{Ru(l-N₄Me₂)}₂{μ-tape-(SO3)₂}]2+ ([4]2+). Complex dication [4]2+ was exploited as a redox mediator between an anaerobic homogenous reaction solution of an enzyme system (sulfite/sulfite oxidase) and the electrode via participation of the low-energy π*-orbital of the disulfonato-substituted bridging ligand tape–(SO₃3)₂2− (Ered1=−0.1 V versus Ag/AgCl/1 m KCl in water).
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