Supramolecular liquid-crystalline dendrimers

Ponomarenko, S.A., Boiko, N.I., Shibaev, V.P., Richardson, R.M., Whitehouse, I.J., Rebrov, E.A., et al., 2000. Carbosilane liquid crystalline dendrimers from molecular architecture to supramolecular nanostructures. Macromolecules 33, 5549—5558. 

This chapter highlights with selected examples some relevant results we have obtained in the field of fullerene-containing thermotropic liquid-crystalline dendrimers. These examples will demonstrate the wide application of dendrimers in designing supramolecular fullerene materials. In the following sections, the structures and properties will be presented according to the nature of the dendrimers and mesogenic units. 

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... 

Such mesogenic systems represent a class by themselves often referred to as dendromesogens. The dendritic concept results from the self-organization of these dendromesogens into various liquid crystalline morphologies. Cylindrical supramolecular dendrimers are generally obtained by the self-assembly... 

Wedge-shaped dendrons such as those described above form mainly columnar and cubic phases. However, a liquid-crystalline phase with a tetragonal three-dimensional unit cell (Tet phase) containing 30 globular supramolecular dendrimers has been reported recently. Each of these supramolecular dendrimers is the result of the self-assembly of 12 dendrons, as is shown in Fig. 8 [120,121]. Interestingly, the complex tetragonal phase of symme-... 

C.J. Hawker and J.M.J. Fechet, Preparation of polymers with controlled molecular architecture. A new covergent approach to dendritic macromolecules, J. Am. Chem. Soc., 1990, 112, 7638 F. Zeng and S.C. Zimmerman, Dendrimers in supramolecular chemistry from molecular recognition to self-assembly, Chem. Rev., 1997, 97, 1681 D.J.P. Yeardley, G. Ungar, V. Percec, M.N. Holerca and G. Johnsson, Spherical supramolecular minidendrimers self-organized in an inverse micellar -like thermotropic body-centered cubic liquid crystalline phase, J. Am. Chem. Soc., 2000, 122, 1684. 

Percec V, Johansson G, Ungar G, Zhou JP (1996) Fluorophobic effect induces the self-assembly of semifluorinated tapered mtmodendrons containing crown ethers into supramolecular columnar dendrimers which exhibit a hraneotropic hexagonal columnar liquid crystalline phase. J Am Chem Soc 118(41) 9855-9866... 

Balagurusamy VSK, Ungar G, Percec V, Johansson G (1997) Ratiraial design of the first spherical supramolecular dendrimers self-organized in a novel thermotropic cubic liquid-crystalline phase and the determination of their shape by X-ray analysis. J Am Chem Soc 119 (7) 1539-1555. doi 10.1021/ja963295i... 

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