This way and that: Triazolylbiferrocenyl dendrimers can be synthesized with up to 729 termini. Oxidation results in isolable mixed‐valence dendrimers (see picture). In electrochemical studies, these species can recognize ATP2− and PdII, and they can be used to stabilize Pd nanoparticle catalysts.

Several strategies have been used to functionalize 1,3,5-trisubstituted arene-cored dendrimers with the organometallic electron-reservoir moiety [Fe(eta(5)-C(5)H(5))(eta(6)-C(6)Me(6))](+), 1, to provide dendritic multielectron reservoirs. They all start from the carboxylic acid [Fe(eta(5)-C(5)H(4)COOH)(eta(6)-C(6)Me(6))][PF(6)], 2, or its acyl chloride derivative [Fe(eta(5)-C(5)H(4)COCl)(eta(6)-C(6)Me(6))][PF(6)], 3. For this purpose, a series of new polyamine dendrimers from G(0) to G(2) with 1--> 3 C connectivity of the branching to the core have been synthesized. Amide, "click" and ionic ammonium carboxylate linkage successfully provided G(0), G(1), and G(2) metallodendrimers with 9, 27, and 81 cationic terminal organoiron groups respectively. Further construction of large metallodendrimers up to G(7) with approximately 14 000 organoiron termini was only possible by combining amide, "click", and tether lengthening strategies to avoid steric bulk at the dendrimer periphery. Reduction of the 18-electron Fe(II) metallodendrimers, exemplified by a G(4)-DAB-64-Fe(II) complex, was achieved exergonically using the parent electron-reservoir complex [Fe(eta(5)-C(5)H(5))(eta(6)-C(6)Me(6))], 1a, at -30 degrees C in MeCN, which allowed further reduction of 64 equiv of C(60) to C(60)(*-) using the 19-electron Fe(I) metallodendrimer.

Production of hydrogen (H2) upon hydrolysis of inorganic hydrides potentially is a key step in green energy production. We find that visible-light irradiation of aqueous solutions of ammonia-borane (AB) or NaBH4 containing "click"-dendrimer-stabilized alloyed nanocatalysts composed of nanogold and another late transition-metal nanoparticle (LTMNP) highly enhances catalytic activity for H2 generation while also inducing alloy to Au core@M shell nanocatalyst restructuration. In terms of visible-lightinduced acceleration of H2 production from both AB and NaBH4, the Au1Ru1 alloy catalysts show the most significant light boosting effect. Au-Rh and Au-PtNPs are also remarkable with total H2 release time from AB and NaBH4 down to 1.3 min at 25 °C (AuRh), three times less than in the dark, and Co is the best earth-abundant metal alloyed with nanogold. This boosting effect is explained by the transfer of plasmon-induced hot electron from the Au atoms to the LTMNP atoms facilitating water O-H oxidative addition on the LTMNP surface, as shown by the large primary kinetic isotope effect kH/kD upon using D2O obtained for both AB and NaBH4. The second simultaneous and progressive effect of visible-light irradiation during these reactions, alloy to Au core@M shell restructuration, enhances the catalytic activity in the recycling, because, in the resulting Au core@M shell, the surface metal (such as Ru) is much more active that the original Au-containing alloy surface in dark reactions. There is no light effect on the rate of hydrogen production for the recycled nanocatalyst due to the absence of Au on the NP surface, but it is still very efficient in hydrogen release during 4 cycles, due to the initial light-induced restructuration, although it is slightly less efficient than the original nanoalloy in the presence of light.The dendritic triazole coordination on each LTMNP surface appears to play a key role in these remarkable light-induced processes.