The research recently carried out in our laboratories is summarized and discussed in the literature context towards green chemistry (dendritic catalysts) and nanotechnology: (i) construction of giant dendrimers far beyond the De Gennes dense-packing limit using building blocks efficiently synthesized by organo-iron activation of simple arene; (ii) use of water-soluble star-shaped organo-iron redox catalysts for nitrate and nitrite cathodic reduction in water; (iii) synthesis of giant dendritic stars from three generations of ruthenium-carbene dendrimers using ROMP and remarkable dendritic effects; (iv) assembly of dendronized gold nanoparticles that selectively recognized H2PO4 – and ATP2–; (v) electron-reservoir metallodendrimers serving as molecular batteries and the example of C60. To cite this article: D. Astruc et al., C. R. Chimie 6 (2003).