Host-guest chemistry of dendritic molecules

In this chapter we will discuss the contribution of dendritic macromolecules to the field of supramolecular host-guest chemistry. Since the first publications on dendrimers more than two decades ago, their properties as molecular recognition compounds have been discussed many times. A brief introduction to the common host-guest interactions in the traditional supramolecular field is accompanied by a short overview of specific properties of these highly branched, three-dimensional macromolecules. Emphasis will be placed on the existence of internal voids in the dendritic interior. Subsequently, an overview will be given of the reported host-guest systems based on dendritic molecules. The host-guest systems discussed are arranged by type of interactions: from topological encapsulation to electrostatic, hydrophobic or hydrogen-bonding interactions. This review will emphasize contributions in which the pre-organized three-dimensional dendritic structure and the high local concentrations of sites display cooperative effects and which could be of interest towards future applications

Some unique features of dendrimers based upon self-assembly and host-guest properties

This chapter has sections titled: Introduction Self-Assembly of Dendrimers Host-Guest Chemistry of Dendritic Macromolecules Conclusion and Prospects Reference

Liquid-liquid extractions using poly(propylene imine) dendrimers with an apolar periphery

The prepn. and ESR spectroscopy of a series of fully functionalized poly(propylenimine) dendrimers (DAB-dendr-(NH2)n; n = 2, 4, 8, 16, 32, 64) with 3-carboxy-PROXYL radical end groups is described. The pendant nitroxyl end groups exhibit a strong exchange interaction. As a consequence, the ESR spectrum directly reveals the no. of end groups from the splitting between the hyperfine transitions for the lower generations. For the higher generations an increasingly exchanged-narrowed ESR spectrum is obsd. The temp. and solvent dependency of the exchange interaction is used to assess the dynamic behavior of the dendritic branches. FT-IR spectroscopy shows that a hydrogen-bonded network between the amide functionalities is present, consistent with the obsd. solvent effect on the ESR spectr

Polystyrene-dendrimer amphiphilic block copolymers with a generation-dependent aggregation

Contains fulltext : 17220.pdf (publisher's version ) (Open Access

Structure of dendrimer-dye host-guest complexes as revealed by small-angle X-ray scattering

Small angle X-ray scattering (SAXS) expts. were performed on dil. aq. solns. of a new type of water-sol. ethyleneoxy-terminated poly(propyleneimine) dendrimer system. They reveal that the dimensions and d. distributions of the dendrimer are hardly affected by a change in the degree of protonation. This is in contrast to recent predictions regarding the structure of polyelectrolyte dendrimers but in line with the results of recent structural studies on charged PAMAM dendrimers. These dendrimer systems were applied as nanosized containers for guests like xanthene dyes. Structural studies with SAXS provide clear evidence for a complex formation but despite higher molar mass the max. dimensions of the complex are only slightly changed compared to the dendritic host. Since the radius of gyration represents the second moment of the electron d. distribution it appears to be very sensitive to changes in this distribution upon encapsulation of heavy-atom contg. guest mols. These are reflected in a decrease of the radius of gyration upon an increase of the guest-host ratio in the soln., a behavior that strongly indicates an accumulation of guest mols. in the center of the dendritic host. [on SciFinder (R)

Amphiphilic block copolymers based on quaternized poly(propylene imine) dendrimers

Contains fulltext : 17237.pdf (publisher's version ) (Open Access