Bis(2,2'-bipyridine)(5,6-epoxy-5,6-dihydro-[1,10]phenanthroline)ruthenium: synthesis and electrochemical and electrochemiluminescence characterization.

In this work, an electrochemiluminescence (ECL) reagent bis(2,2'-bipyridine)(5,6-epoxy-5,6-dihydro-[1,10]phenanthroline)ruthenium complex (Ru-1) was synthesized, and its electrochemical and ECL properties were characterized. The synthesis of Ru-1 was confirmed by IR spectra, element analysis, and (1)H NMR spectra. For further study, its UV-vis absorption and fluorescence emission spectra were investigated. Ru-1 also exhibited quasi-reversible Ru (II)/Ru (III) redox waves in acetonitrile solution. The aqueous ECL behaviors of Ru-1 were also studied in the absence and in the presence of tripropylamine. The complex was fabricated on a gamma-(aminopropyl) triethoxysilane (APTES) pretreated indium tin oxide (ITO) substrate via aminolysis reaction between the 5,6-epoxy-5,6-dihydro-[1,10]phenanthroline ligand and APTES. The resulting Ru-1 modified ITO substrate exhibited a broad absorption band in the visible region (350-600 nm) and its fluorescence emission spectrum was centered at 622 nm. The Ru-1 modified ITO electrode showed relative low ECL response. To improve the solid-state ECL response, a gold nanoparticles (GNP)/Ru-1 modified ITO electrode was constructed. The mixing of GNP and Ru-1 could produce the aggregates, which were further immobilized onto a 3-mercaptopropyltrimethoxy-silane (3-MPTMS) pretreated ITO substrate via Au-S interactions to construct the GNP/Ru-1 modified electrode.