Large ferrocenyl dendrimer

Convergent and Divergent Syntheses of Large Ferrocenyl Dendrimers with Good Redox Stabilities 421... 

Dendrimers are large molecules, and their solubility is often an issue. Thus, it is not surprising that dendrimers can be good candidates to precipitate upon and thus modify the surface of an electrode. Dendrimers with ferrocenyl peripheral units were shown to display well-defined redox waves with the ferrocenyl units oxidizing independently.176-178 These molecules oxidatively precipitated onto the electrode surface and were characterized electrochemically and by atomic force microscopy.44 It was later shown that cyclodextrin complexation increased the solubility of these molecules.179 Similar results were obtained with dendrimers containing pendant ruthenium tris (bipyridine) and bis(terpyridine) groups.180... 

A number of research groups have reported the preparation of a large number of star-shaped molecules and dendrimers containing ferrocenyl or arene cyclopentadienyliron complexes at the core or the peripheries.300-320 A number of these dendrimers were prepared via cyclopentadienyliron-mediated per-alkylation, -benzylation and -allylation reactions of cationic tri-, tetra- and hexamethylbenzene complexes. These dendrimers were multifunctional materials and have been used in the synthesis of branched organic and organometallic polymers. 

The versatile chemistry of the ferrocenyl moiety has also allowed for the preparation of a large number of dendrimeric structures with this group at the periphery (116-118). A series of dendrimers based upon polypropylenimine cores have been reported (119,120) and star-shaped macromolecules with ferrocene units at the periphery have been produced (121), as well as amido-ferrocene dendrimers (eg, 38) (122). A convergent approach has allowed for the synthesis of dendrimers (39) for which the ferrocene units at the periphery display electronic interaction (123). 

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