Electrogenerated chemiluminescence reactions between the [Ru(bpy)3](2+) complex and PAMAM GX.0 dendrimers in an...

Electrogenerated chemiluminescence, ECL, reactions between tris(2,2'-bipyridine)ruthenium(II), [Ru(bpy)3](2+), and PAMAM GX.0 (X=1 and 2) dendrimers in an aqueous medium were carried out at pH10 (fully deprotonated dendrimer surface). ECL was detected in the presence of GX.0 dendrimers without addition of any known coreactant. Atomic force microscopy, AFM, measurements for GX.0 dendrimers in the presence of the [Ru(bpy)3](2+) complex were also done. AFM images showed the existence of aggregates (pillars) of globular shape, as well as interdendrimer networks forming fibers in the x-y direction for dendrimer aqueous solutions. ECL and AFM results in cooperation suggest that the coreactant effect of the end amine groups is improved by both the dendritic branched shells and the globular z-type aggregates. The ECL efficiency trends as a function of [GX.0] (whole range) can be interpreted taking into account the coreactant effect modulated by the presence of the z and x-y type aggregates. Importantly, ECL efficiency values can be taken as a measure of the change induced on the dendrimer aggregation in aqueous solutions when their concentrations rise. Redox potentials of the [Ru(bpy)3](3+/2+) couple in the presence of the G1.0 and G2.0 dendrimers were also determined.