Preparation of Pt Nanoparticles Templated by Poly(amidoamine) Dendrimers

The complexation of pt(2+) ions with G5.5-COOCH3 PAMAM dendrimers was investigated by UV-VIS and FT-IR spectral methods, showing that Pt2+ ions are coordinated with the interior amino groups of dendrimers. It needs more time for the complexation reaction to come to balance with the increase of molar ratios of pt(2+) ions to dendrimers. The maximum loadings of 50 similar to 55 Pt2+ ions within the G5.5-COOCH3 dendrimers were also obtained. Following reduction with NaBH4 resulted in spherical and well-dispersed Pt nanoparticles (average size < 2 nm) encapsulated in the dendrimers as shown in HRTEM images. When the ratio of pt2+ Ions to dendrimers was 10, the yielded Pt nanoparticles with smaller sizes and a narrow distribution were intradendrimer templated. When the ratio of Pt2+ ions to dendrimers was 50, new partially formed Pt nanoparticles with larger sizes and a broad distribution were interdendrimer templated.