Birth of a new macromolecular architecture: dendrimers as quantized building blocks for nanoscale synthetic polymer chemistry

This review is introduced by an examination of the historical roles that quantized building blocks, such as atoms and monomers have played in the development of small molecule and traditional polymer synthesis, respectively. The unique features of traditional macromolecular architectures (i.e. linear, crosslinked, branched), as well as controlled nanostructures in biology were used as frames of reference to anticipate potential new properties, phenomena and synthetic constructs that should be expected to emerge at the interface of the 'dendritic architectural state' with the nanotechnology revolution. Intrinsic new properties associated with the 'dendritic architectural state', such as the ability to control monodisperse nanoscale sizes, shapes and presentation of surface functionality are reviewed. Unique 'dendritic effects' related to de Gennes dense packing (i.e. unimolecular encapsulation, periodic nanocontainer properties), polyvalency (nanoscaffolding), as well as shape designing both within (i.e. cystamine core dendrimers) and beyond dendrimers (i.e. core-shell tecto(dendrimers)) to mimic biological proteins are described. The precise, quantized coreshell architectural properties and monomer shell filling features of dendrimers are compared to the electron shell filling patterns of elemental atoms by utilizing the Niels Bohr Periodic Table. This comparison has provided a rationale for explaining autoreactivity patterns observed at the sub-nanoscale (atoms), lower nanoscale (dendrimers) and higher nanoscale levels involving either unsaturated electron shells, monomer shells or dendrimer shells, respectively. Clearly, dendritic polymers, especially dendrons and dendrimers are expected to fulfill important roles as fundamental, reactive modules for nanoscale polymer syntheses. (c) 2005 Elsevier Ltd. All rights reserved.