Hexa amphiphilic

FIG. 19 H-A isotherms of amphiphilic hexa-azacrown (noted as 3 in the figure) and 1 1 mixtures with C60 andC70 (top) and for 1 1, 1 2, and 1 3 mixtures of C60 and the amphiphilic hexa-azacrown (bottom). (Reproduced from Ref. 254 with permission of the author. Copyright 1991 Wiley-VCH.)... 

Fukushima and Aida et al. reported that an achiral amphiphilic hexa-pen-hexabenzocoronene (HBC) 3 self-assembles into a helical coil and further into nanotubes in THF containing water (20% v/v) (Fig. 2) [37]. TEM revealed... 

Research on liquid crystals with a disc-like shape started in 1977 [130] when hexa(hep-tanoyl)benzene (38, first synthesized forty years earlier [131]) was proved to form a columnar mesophase (m.p.=/tj, 81.2°C, cl.p.=/ci 87.0°C) [132]. Disc-shaped amphiphilic molecules with saturated cores, such as the hexaesters 39 or even the hexa-ethers 40 of the naturally occurring scyllo-inositol [9, 109, 133-137] form columnar liquid crystals much more easily with me-sophases more stable and very much wider in range than known for the mentioned benzene derivatives. 

S. Kubowicz, U. Pietsch, M.D. Watson, N. Tchebotareva, K. Mullen, A.F. Thunemann, Thin layers of columns of an amphiphilic hexa-peri-hexabenzocotonene at silicon wafer surface. Langmuir 19, 5036-5041 (2003)... 

N. Reitzel, T. Hassenkam, K. Balashev, T.R. Jensen, P.B. Howes, K. Kjaer, A. Fechtenkotter, N. Tchebottareva, S. Ito, K. Mullen, T. Bjornholm, Langmuir and Langmuir-Blodget films of amphiphilic hexa-peri-hexabenzocoronene new phase transitions and electronic jHoperties by pressure. Chem. Eur. J. 7, 4894-4901 (2001)... 

Lee M, Kim J-W, Peleshanko S et al (2002) Amphiphilic hairy disks with branched hydrophilic tails and a hexa-pen-hexabenzocoronene core. J Am Chem Soc 124 9121-9128. doi 10.1021/ja017553... 

Fig. 3.1 Building blocks of thermotropic and lyotropic liquid crystalline phases. The upper part of the figure shows two examples of typical thermotropic mesogens. Calamitic mesogens, such as terephthal-bis-(p-butylaniline) (TBBA) [2], can be represented by prolate ellipsoids or rigid rods, while discotic mesogens, such as benzene-hexa-n-octanoate (BH8) [4], are usually described by oblate ellipsoids or discs. The lower part of the figure shows the typical surfactant molecule sodium dodecyl sulfate (SDS), which forms lyotropic phases with water [5], Such a surfactant molecule is basically composed of a polar head group and a flexible hydrophobic tail. These amphiphilic molecules aggregate into different types of micelles, which are the actual mesogens of lyotropic liquid crystals. The shape of the micelles depends mainly on the solvent concentration...

The amphiphilic hexa-peri-hexabenzocoronene (A-HBC) that contains two alkyl chains on one side and two polyethylene glycol chains on the opposite side (Figure 13b) was observed to self-assemble in tetrahydrofuran into... 

One example of amphiphilic block copolymer is poly(methoxypolyethyleneglycol cyanoacrylate-co-hexadecyl cyanoacrylate), synthesized for the first time by Peracchia et al. [35]. This polymer naturally combines the advantages of long-chain cyanoacrylates with the positives of PEG chains (amphiphilic nature) with the goal to increase the blood lifetime of nanoparticles. The copolymer can be prepared at various hexa-decyl/PEG chain ratios however, a hexadecyl/PEG ratio of 4 1 was foimd more suitable for pharmaceutical applications. In this case a good balance between hydrofilicity and lipophilicity is obtained, with low solubility in water but at the same time solubility in water-miscible solvents guaranteed [35,36]. 

The discotic 2,3,6,7,10,1 l-hexa-(l,4,7-trioxaocetyltriphenylene) amphiphilic molecule [13] in Fig. 4 (cf. also Section n.E and this volume. Chapter 2) can form single polymeric columnar assemblies stabilized by supramolecular bonds perpendicular to the monomeric surface in nematic solutions containing up to 50% solvent. The tapered 12-ABG-B15C5 compound [14] in Fig. 5, complexed with 0.4 M triflate salt per mole of the crown ether receptor B15C5, self-assem-bles into an hexagonal columnar (( ), ) mesophase revealed by X-ray and optical microscopy in the undiluted system. The column cross-section is based on disks... 

Figure 4 The discotic amphiphile 2,3,6,7,10,1 l-hexa-(l,4,7-trioxaocethyltriphenylene) is the repeating unit in a columnar stack stabilized by solvophobic interactions in D2O. The temperature versus volume fraction phase diagram shows that single stacks occur in the nematic phase (N) at volume fraction as low as 0.2. Hexagonal columnar and eventually crystalline phases evolve upon increasing concentration. (From Ref. 13.)...

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