The 1,6,7,12-Tetraazaperylene Bridging Ligand as an Electron Reservoir and Its Disulfonato Derivative as Redox Mediator in an Enzyme–Electrode Process

5 years ago

The 1,6,7,12-Tetraazaperylene Bridging Ligand as an Electron Reservoir and Its Disulfonato Derivative as Redox Mediator in an Enzyme–Electrode Process

Uwe Schilde, Hans-Jörg Krüger, Hans-Jürgen Holdt, Harald Kelm, Ulla Wollenberger, Manuel Reh, Thomas Brietzke, Julianae Bois, Silke Leimkühler, Markus Schmitz, Thomas Dietz, Thomas Körzdörfer, Alexandra Kelling

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–(SO3)22− (Ered1=−0.1 V versus Ag/AgCl/1 m KCl in water). Full of negativity: The redox-active bridging ligand 1,6,7,12-tetraazaperylene (tape) contained in a dinuclear ruthenium(II) complex can store up to two electrons, demonstrated by the isolation and characterization of the singly and doubly reduced dinuclear complexes. The high π-accepting potential of the tetraazaperylene bridge can be increased further by introducing two sulfonato groups. The corresponding complex works as a redox mediator in a voltammetric enzyme–electrode system.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/chem.201703639