Self dendrimer

The sequential growth and branching involved in the preparation of dendrimers had been considered by Flory many years before they were actually prepared. Flory developed a sound understanding of the kind of processes that would occur in the self-polymerization of a molecule of the type ABj most of which have been shown to be correct by the relatively recent experimental studies. In particular, the existence of a limit to growth was predicted. This limit has become known as the starburst limit, and is the reason for the highly monodisperse nature of fully developed dendrimers. 

There are a variety of routes currently utilized to fabricate a wide range of hollow capsules of various compositions. Among the more traditional methods are nozzle reactor processes, emnlsion/phase-separation procednres (often combined with sol-gel processing), and sacrificial core techniques [78], Self-assembly is an elegant and attractive approach for the preparation of hollow capsules. Vesicles [79,80], dendrimers [81,82], and block hollow copolymer spheres [83,84] are all examples of self-assembled hollow containers that are promising for the encapsnlation of various materials. 

Keywords. Rotaxane dendrimers. Host-guest interaction, Recognition, Self-assembly, Supra-molecular chemistry... 

The use of ordered supramolecular assemblies, such as micelles, monolayers, vesicles, inverted micelles, and lyotropic liquid crystalline systems, allows for the controlled nucleation of inorganic materials on molecular templates with well-defined structure and surface chemistry. Poly(propyleneimine) dendrimers modified with long aliphatic chains are a new class of amphiphiles which display a variety of aggregation states due to their conformational flexibility [38]. In the presence of octadecylamine, poly(propyleneimine) dendrimers modified with long alkyl chains self-assemble to form remarkably rigid and well-defined aggregates. When the aggregate dispersion was injected into a supersaturated... 

Self-assembly of functionalized carboxylate-core dendrons around Er +, Tb +, or Eu + ions leads to the formation of dendrimers [19]. Experiments carried out in toluene solution showed that UV excitation of the chromophoric groups contained in the branches caused the sensitized emission of the lanthanide ion, presumably by an energy transfer Forster mechanism. The much lower sensitization effect found for Eu + compared with Tb + was ascribed to a weaker spectral overlap, but it could be related to the fact that Eu + can quench the donor excited state by electron transfer [20]. 

Self-assembly of aromatic dendron subunits has been tried by the design of coordination to multivalent metal cations (i.e., metal-cored dendrimer complexes). Several metal-cored dendrimer complexes have successfully exhibited luminescence by antenna effects. 

We have found that dendrimers can be used to encapsulate active moieties, thereby preventing them from interacting. This passivation effect limits inter-molecular interactions such as self-aggregation and molecular clustering. We also found that dendrimers can be made dipolar. This asymmetry in molecular orientation enables dendrimers to be used in NLO. In this chapter we describe our application of dendrimers to lasers and NLO. 

Figure 8.9 Schematic representation of a conical monodendron self-assembled into a supramolecular spherical micellar dendrimer, and then into an fm3m cubic mesophase.

SELF-IMMOLATIVE DENDRIMERS BASED ON QUINONE METHIDES... 

ENZYMATIC ACTIVATION OF SECOND-GENERATION SELF-IMMOLATIVE DENDRIMERS... 

Amir, R. J. Shabat, D. Self-immolative dendrimer biodegradability by multi-enzymatic triggering. Chem. Commun. 2004, 1614-1615. 

Adler-Abramovich, L. Perry, R. Sagi, A. Gazit, E. Shabat, D. Controlled assembly of peptide nanotubes triggered by enzymatic activation of self-immolative dendrimers. Chem. Biochem. 2007, 8, 859-862. 

Shabat, D. Self-immolative dendrimers as novel drug delivery platforms. J. Polym. Sci. A Polym. Chem. 2006, 44, 1569-1578. 

Gopin, A. Ebner, S. Attali, B. Shabat, D. Enzymatic activation of second-generation dendritic prodrugs conjugation of self-immolative dendrimers with poly(ethylene glycol) via click chemistry. Bioconj. Chem. 2006, 17, 1432-1440. 

Many opportunities conversely are supported by reversible reactions of QM despite the noted complications. One example includes the synthesis and chiral resolution of binaphthol derivatives by two cycles of QM formation and alkylation.77 The reversibility of QM reaction may also be integrated in future design of self-assembling systems to provide covalent strength to the ultimate thermodynamic product. To date, QMs have already demonstrated great success in supporting the opposite process, spontaneous disassembly of dendrimers (Chapter 5). 

Self-Immolative Dendrimers Based on Quinone Methides 119... 

Cleavage Signal Conduction in Self-Immolative Dendrimers 154... 

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