Shape surface chemistry

D. A. Tomalia, A. M. Naylor, and W. A. Goddard, Starburst dendrimers-molecular level control of size, shape, surface chemistry, topology, and flexibility from atoms to macroscopic matter, Angew. Chem. Int. Ed. Engl., 29 (1990) 138-175. 

This lecture exposed these rather revolutionary concepts to an elite scientific community in Europe. Secondly, an invitation by Dr. P. Golitz (Editor, Angew. Chem.) to publish an important review [20] entitled Starburst dendrimers molecular-level control of size, shape, surface chemistry, topology and flexibility from atoms to macroscopic matter provided broad exposure to the basic concepts underlying dendrimer chemistry. Finally, important contributions by key researchers significantly expanded the realm of dendrimer chemistry with the convergent synthesis approach of Frechet and Elawker [37] (Figure 4), as well as the systematic and critical photophysical characterization of Turro et al [38],... 

Tomalia DA, Naylor AM, Goddard HI WA. Starburst dendrimers control of size, shape, surface chemistry, topology and flexibility in the conversion of atoms to macroscopic materials. Angew Chem 1990 102 119-157. 

The core (ingredients, size, shape, surface chemistry, physical attributes, etc.)... 

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. 

In addition to size, the toxicity of nanomaterials depends on the shape, surface chemistry, surface charge, and chemical composition of the particle, among other characteristics. For example, nanoparticles of cobalt and manganese can enter cells, although salts of cobalt and manganese cannot. These nanoparticles are significantly more toxic than their salt counterparts. There is no scientific consensus about which characteristics are the most important determinants of toxicity. ... 

The physical properties of QDs are ultimately the end products of a complex interplay of several fundamental processes that need to be recognised and understood before these materials may be used efficiently in devices. The optical properties of nanomaterials arise from interactions between electrons, holes, and their local environments. These properties may be affected by parameters such as size, shape, surface chemistry, dopants, the presence of other nanostructures, as well as other still undetermined characteristics of the surrounding environment. Spectroscopic probes of such optical properties thus convey a wealth of information on the behaviour and... 

Tomalia, D.A., Naylor, A.M., Goddard, W.A. Starburst Dendrimers - Molecular-Level Control of Size, Shape, Surface-Chemistry, Topology, and Flexibility from Atoms to Macroscopic Matter. Angew. Chem. Int. Edit. 29(2), 138-175 (1990). doi 10.1002/Anie. 199001381... 

The biotic molecular evolution was defined by the respective CADPs of the combined (atoms) required to produce this new molecular level order. It is now known that within this hierarchical level, new sizes, shapes, surface chemistries (functional groups/nonbonding interactions), flexibilities (conformations), and topologies (architectures) arise. These parameters may be visualized by the various shapes, valencies, and polarizabilities associated with the element carbon in its well-known sp, sp, or sp hybridized states. We define fhese unique features as critical small molecule design parameters — CSMDPs. Molecular entities in this domain are generally < 1000 atomic mass units, thus they occupy space of up to approximately 10 A (1 nm) in diameter, when normalized as spheroids. They may be thought of as subnanoscale in dimension. 

The stmcture-controlled features manifested by dendrons/dendrimers, such as size, shape, surface chemistry, flexibility/rigidity, elemental composition, and architecture, have provided a unique window to a new systematic concept for unifying nanoscience and will be described later in Section 6. These nanolevel structure-controlled features are referred to as critical nanoscale design parameters (CNDPs). 

We now examine recent progress reported by Percec, Rosen and colleagues [151] that has clearly demmistrated the first working examples of predictive, Mendeleev-like nano-periodic tables. These Percec nano-periodic tables clearly demonstrate a priori predictions for the mode of [S-l]-type amphiphilic dendron self-assembly into supramolecular dendrimers with 85-90% accuracy. Quite remarkably, as proposed in the original concept [137], these self-assembly modes may be accurately predicted based on simply knowing the CNDPs (size, shape, surface chemistry, and flexibility) for the amphiphilic dendron primary structure, as will be described in the next sectimi. 

Furthermore, it was shown by Percec and coworkers [151] that simply by knowing the four CNDPs (size, shape, surface chemistry, and flexibility) of the primary dendron stmcture, one could predict self-assembly patterns leading to tertiary and quaternary structures with greater than 85-93% accuracy, as shown in Fig. 36. 

Figure 4.73. PRINT particles varying in size, shape, surface chemistry, and deformability. The particle composition for all of these particles was approximately the same and included PEG (bulk of the matrix), a cross-linker, and a linker group for conjugation of stabilizing groups (such as PEG) or targeting ligands...

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