Functionalization of PAMAM dendrimers with [RuIII(edta)(H2O)]−

The anchoring of K[RuIII(edta)(Cl)] on poly(amidoamine) dendrimers (PAMAM of three generations Gx/Ru (x = 0, 2 and 3)) through a peptide type bond yielded the aquo species, [RuIII(edta)(H2O)] on dendrimer surface, and upon NO exposure, yielded their nitrosyl analogues, Gx/RuNO. Characterization of these compounds by elemental analysis, and a UV–vis, IR and 13C NMR spectroscopies indicated the immobilization of 4, 12 and 29 molecules of [RuIII(edta)(H2O)] or of the nitrosyl complex [RuII(edta)NO] on the dendrimer surface for GX = 0, 2 and 3, respectively. For each complex the electrochemical spectrum presented only one redox process with redox potential values of −0.20 and −0.32 V(vs SCE) attributed to the RuIII/RuII and NO+/NO0 couples in Gx/Ru and Gx/RuNO, respectively. The one-electron reduction of Gx/RuNO+ generates Gx/RuNO0, which undergoes aquation with a k–NO of 2.1 ± 0.7 × 10−3 s−1 (pH 1.0, μ = 0.2 mol/L, CF3COOH/NaCF3COO, 25 °C). The Gx/RuNO species induced a relaxing effect in aortic rings denuded of endothelium and exhibited in vitro assay trypanocidal activity.