Dendrons/dendrimers: quantized, nano-element like building blocks for soft-soft and soft-hard nano-compound synthesis

Abstract

It was A. Lavoisier's original thinking in Traite Elementaire de Chemie (1789) followed by J. Dalton's seminal “atom/molecular hypothesis” (i.e., New System of Chemical Philosophy, 1808) that defined “first principles” for much of our contemporary small molecule chemistry. Dalton's concept, advocating atom-based (elemental) building blocks (0.1–0.6 nm) for the synthesis of well defined small molecules, has emerged as a fundamental theme over the past 200 years. It initiated fundamental concepts such as well defined mass combining ratios, stoichiometries, valency and compound formation which have defined the “central dogma” and underpinned the traditional fields of both organic/polymer and inorganic sciences. As such, these historical examples portend the significant role that similar well defined, quantized soft nano-matter, modules such as dendrons and dendrimers (1.0–20 nm) might be expected to play in the emerging science of nano-syntheses. Dendrimers are well defined collections of atoms that may be viewed as core-shell type atom mimics (i.e., soft nano-element like modules). More than 12,000 published references in the dendrimer field have clearly demonstrated the ability to structure control important Critical Nanoscale Design Parameters (CNDPs) such as: (a) size, (b) shape, (c) surface chemistry, (d) flexibility and (e) architecture over a wide range of structures and compositions. These are features shared with elemental atoms and account for unique atom-like combining properties exhibited by dendrimers to yield well defined nano-module stoichiometries. We report first steps, including many literature examples that demonstrate the construction of well defined soft-soft and soft-hard matter nano-compounds. A variety of dendrimer surface reactions or guest-host assemblies have been shown to produce stoichiometric nano-compounds such as: (a) dendrimer-dendrimer, (b) dendrimer-protein (c) dendrimer-fullerene and dendrimer-metal nanocluster structures, to mention a few. These literature examples provide compelling evidence for the emergence of an active dendron and dendrimer module based synthetic nano-chemistry platform.