Polyamidoamine dendrimers functionalized with electrochemiluminescent polypyridyl Ru(II) complexes

Polyamidoamine (PAMAM) dendrimers that is surface-modified with electrochemiluminescent (ECL) polypyridyl Ru(II) complexes, Dend-4-[Ru(L)2(L′)] (L = bpy, o-phen; L′ = bpy-CO-, mbpy-(CH2)3CO-), were synthesized through complexation of dendritic polypyridyl ligands to Ru(II) complexes to study the effect of both ligand and dendritic network on the ECL. Their electrochemical redox potentials, photoluminescence (PL) and relative ECL intensities were also studied. The ECL emissions produced by the reaction between electro-oxidized Ru3+ species of PAMAM dendrimers and tripropylamine as a coreactant were measured in a static system with potential cycles between 0.8 and 1.3 V or a flow injection analysis with a potential of +1.3 V and compared with that of [Ru(bpy)3](PF6)2. Dend-4-[Ru(bpy)2(mbpy-(CH2)3CO-)](PF6)8 showed two-fold intense ECL intensity, greater than that shown by [Ru(bpy)3](PF6)2 complex. It is observed that both ligand and length of spacer connected to dendrimer affected the ECL intensity.