Arborols synthesis

The use of dendrimers as micelles was envisaged by Newkome in 1985 and was the driving force behind the gronp s original arborol synthesis however, it was not nntil 1989 that the first evidence for this phenomenon was reported by Tomalia et al. Dramatic decreases in the T relaxation times for nuclei of acetylsalicylic acid were observed when measured in solution with PAMAM dendrimers above the fourth generation, when compared to measurements recorded in solutions that contained lower generation dendrimers. This result indicated that the acetylsalicylic acid probes were at least transiently encapsulated within dendrimers. Turro and coworkers have also demonstrated encapsulation of metal ions within dendritic structures when solutions of Cu(II) and acid-terminated... 

The synthesis and study of dendrimers is a relatively new branch of macro-molecular chemistry. It began in 1985 with the publication of two landmark papers (D.A. Tomalia, H. Baker, J. Dewald, J.M. Hall, G. Kallos, R. Martin and J. Ryder, Polym. J., 1985,17,117-132 and G.R. Newkome, Z. Yao, G.R. Baker and V.K. Gupta, J. Org. Chem., 1985, 50, 2003-2004), and has grown to become a very vibrant research field. The word dendrimer comes from the Greek word dendra, meaning tree, and was applied to these compounds by Tomalia et al. in their very first paper. Newkome s team, by contrast, called their molecules arborols from the Latin word arbor, which also means a tree. The term cascade molecule has also been used, but the word dendrimer is the one that is used most widely throughout the literature, and is also used in the present chapter. 

Astruc and co-workers were the first to report divergent a[ roaches to the construction of organometallic molecular trees. A representative example of their exciting synthetic strategy for the synthesis of multimetallic arborols is illustrated in Scheme 8. The growing step is based on the fact that the n-com-plexation of aromatic compounds by electron-withdrawing cationic organo-transi-... 

Since these arborols (111) are comprised of two hydrophilic groups connected by a hydrophobic linkage, they fit the simple definition of a bolaamphiphile a term derived from bolaform amphiphile, originally introduced in 1951 by Fuoss and EdlesonJ128 In 1984, when Fuhrhop and Mathieu 129 reported the synthesis and self-assembly of several bolaamphiphiles, these two-directional surfactant-like macromolecules represented a simple entrance to the bolaamphiphile field this subject has recently been highlighted1130 and reviewed.1131 ... 

Scheme 5.24. Shinkai et al. s[731 procedure for the synthesis of crowned arborols ...

Since 1985, Newkome and co-workers [92-94] have reported the synthesis of related symmetrically branched macromolecules which they refer to as arborols . These macromolecules are highly branched dendrimers which are not amenable to size control as a function of generation in that reiterative chemistry for advancing concentric growth has not been reported. These prototypes have been used successfully for controlling molecular shape and, in some cases, surface moieties. To date, examples of uni-, di- and tri-dendron arborols have been reported [92-94] (see Sect. 5). 

Vogtle s early work on cascade molecules was followed by the synthesis of highly branched polyols in the laboratory of Newcome (Fig. 3) [62], Since the first polyol structures reminded him of small trees, they were named arboroles (lat. arbor - tree). However, it has been the Greek-derived term dendrimer (8ev5pov - tree, pspcx - particle), which has become the most popular term for highly branched monodisperse molecules with fractal character, as first used in a patent... 

Tomalia, Denkewalter and Newkome followed the cascade synthesis for the preparation of Starburst polyamidoamines, polylysines, and arborols during the 80 s and developed the dendrimer chemistry to a high skill. [1]... 

Synthesis and characterization of a zinc(II) phthalocya-nine[8] -arborol. J. Chem. Soc. Chem. Commun. 1997, (13). 1215-1216. 

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