Dendritic molecule 336 Subject

Hyperbranched and dendritic macromolecules have recently been the subject of considerable interest. Bolm developed chiral hyperbranched macromolecules 57 that catalyzed the enantioselective addition of diethylzinc to benzaldehyde [75]. The enan-tiocontrol of the hyperbranched chiral catalysts was slightly lower than for the low-molecular-weight catalyst. TADDOLs linked with dendritic molecules have been synthesized [59]. For example, use of the first generation dendrimer 58 with six terminal TADDOL units resulted in high enantioselectivity. 

Molecules can lose an electron when subjected to a high electric potential resulting in field ionization (FI) [366,534,535]. High fields can be created in an ion source by applying a high voltage between a cathode and an anode called a field emitter. A field emitter consists of a wire covered with microscopic carbon dendrites, which greatly amplify the effective field at the carbon points. 

Construction of organic nanotubes starting from porphyrin dendrimers with core/shell architecture is also feasible. Figure 8.29 also shows how covalent nanotubes can be produced by removal of the dendritic component of the molecule. A coordination polymer is first synthesised from a dendritic metallopor-phyrin with alkene end groups. This is subjected to intramolecular and intermo-lecular crosslinking by ring-closing metathesis at the periphery. 

In more recent years there is a development towards molecular recognition as a tool. Based on the increasing understanding of the weak forces between (macro) molecules we now see new concepts of material design. Chapters 1 to 3 cover three aspects of this development nanostructures that are formed by self-assembly of small molecules (chapter 1), dendritic structures (chapter 2) and polymers (chapter 3). A volume of a series like Perspectives in Supramolecular Chemistry can never claim to cover all aspects of a subject. All I can hope is that these chapters are representative of the filed of supramolecular technology. 

Its characteristic wavelength is subject to the transport of latent heat from the growing interface. This is known as Mullins-Sekerka instability (11), The interface of a growing dendritic crystal provides an open system to support die dissipative structure with its characteristic wavelength(s), and the molecules or ions incorporated into the growing crystal are regarded to be self-assembled into the specific coordinate of dendritic crystal by die assistance of the dissipative structure. 

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