Reduced Graphene Oxide-Immobilized Tris(bipyridine)ruthenium(II) Complex for Efficient Visible-Light-Driven Reductive Dehalogenation Reaction

A sodium benzenesulfonate (PhSO₃Na)-functionalized reduced graphene oxide was synthesized via a two-step aryl diazonium coupling and subsequent NaCl ion-exchange procedure, which was used as a support to immobilize tris­(bipyridine)­ruthenium­(II) complex (Ru­(bpy)₃Cl₂) by coordination reaction. This elaborated Ru­(bpy)₃-rGO catalyst exhibited excellent catalytic efficiency in visible-light-driven reductive dehalogenation reactions under mild conditions, even for ary chloride. Meanwhile, it showed the comparable reactivity with the corresponding homogeneous Ru­(bpy)₃Cl₂ catalyst. This high catalytic performance could be attributed to the unique two-dimensional sheet-like structure of Ru­(bpy)₃-rGO, which efficiently diminished diffusion resistance of the reactants. Meanwhile, the nonconjugated PhSO₃Na-linkage between Ru­(II) complex and the support and the very low electrical conductivity of the catalyst inhibited energy/electron transfer from Ru­(II) complex to rGO support, resulting in the decreased support-induced quenching effect. Furthermore, it could be easily recycled at least five times without significant loss of catalytic reactivity.