Genealogically directed synthesis: Starburst/cascade dendrimers and hyperbranched structures

Abstract

A paradigm shift is in progress which is directed at the mimicry of complex, highly sophisticated biomolecular architecture and phenomena. Mimicry of these targeted phenomena and structures is driven by the realization that these prototypes have been derived and perfected over billions of years in a dazzling molecular level effort to introduce and sustain life. In the past, natural product synthesis or de novo protein/polynucleic acid syntheses have been targeted to produce direct equivalency to various prototypes in biomolecular schemes. Unlike this objective, synthetic structures and strategies in this account will focus on the mimicry of architecture and phenomena found in life processes, utilizing less complex reagents and protocol to give novel products not found in Nature. With this in mind we introduce a new organic synthesis strategy which we refer to as ''genealogically directed synthesis'' (GDS). Simply stated the central theme of this strategy utilizes mimicry of seven key phenomena/architectural criteria invoked by Nature to initiate and sustain life. These criteria deal with the flow and transfer of molecular level information through a chemical hierarchy, be it abiotic or biological. A comparison of such GDS mimicry with certain targeted biomolecular phenomena/-structures is listed below: [GRAPHICS] These seven italicized criteria are integrated into a variety of (GDS) schemes thus allowing construction of hyperbranched macromolecular structures referred to as ''dendrons'' or ''dendrimers''. A direct consequence of this strategy is a systematic ''molecular morphogenesis'' [1] with an opportunity to control ''critical molecular design parameters'' (CMDP's); (i.e., size, shape, surface chemistry, topology and flexibility) as one advances with covalent connectivity from molecular reference points (seeds) of picoscopic/sub-nanoscopic size (i.e.. 0.01-1.0 nm) to precise macromolecular structures of nanoscopic dimensions (i.e., 1.0-100 nm) [2]. Genealogically directed synthesis offers a broad and versatile approach to the construction of precise, abiotic nanostructures with predictable sizes, shapes and surface chemistries.