Synthesis of ru(bpy)3-viologen and its complex included by p-sulfonatocalix[4]arene in a U-type binding manner

A novel Ru(bpy)3–viologen guest RPV and a reference compound PV are well designed and synthesized. Ru(bpy)3 based guest compound RPV prefers to form a novel U-type complex RPV⊂SC4 with p-sulfonatocalix[4]arene (SC4) host. Binding manner of the complex has been fully studied by 1H NMR, ESI-MS and 2D NOE NMR spectra. The 1:1 Binding ratio is confirmed by UV–Vis measurement and the association constant is determined by 1H NMR titration. In this host–guest system, both Ru(bpy)3 and viologen group show strong interactions with the host SC4. Due to the unique U-type structure of RPV⊂SC4, the competitive interactions between Ru(bpy)3 and viologen group were investigated as well.