Dialkyl amphiphiles structures

Another important area of progress is the enlargement of the scope of the structure of aqueous aggregates. The bilayer membrane formed from dialkyl amphiphiles belongs to a new class of the aqueous aggregate, totally different from the conventional surfactant micelle. A trialkylammonium compound gives yet another type of aggregation. 

As discussed in the preceding sections, fluid, globular micelles are formed from monoalkyl surfactants, whereas the liquid-crystalline bilayer structure is formed from a variety of dialkyl amphiphiles and from single-chain amphiphiles with rigid hydrophobic segments. It may then be asked what structure is expected from amphiphiles with three alkyl chains. 

Chiral dialkyl amphiphiles [61] and [62], prepared from alanine and glutamic acid (Kunitake et al., 1979b), also form bilayer structures when dispersed in water. Chiral bilayers should be interesting because they provide... 

Complexes based on the double-helix DNA and oppositely charged surfactants are formed in aqueous solution due to Coulombic attraction between the polyanion chain units and surfactant ions, and they are stabilized by hydro-phobic interaction of nonpolar fragments of the surfactant [4-5]. One can expect that such amphiphilic structure of DNA-surfactant complexes will also promote solubility in low-polarity organic solvents. At present, there is lack of information on the behavior of DNA-surfactant complexes in nonaqueous organic solvents. However, some studies indicate that the complexes based on DNA and cationic dialkyl amphiphiles can be soluble in organic media in the presence of a small amount of water [6]. We... 

Several laboratories have described systems by which synthetic linear peptide chains self-assemble into desirable secondary and tertiary structures. One self-assembly approach has been the creation of a peptide-amphiphile, whereby a peptide head group has the propensity to form a distinct structural element, while a lipophilic tail serves to align the peptide strands and induce secondary and tertiary structure formation, as well as providing a hydrophobic surface for self-association and/or interaction with other surfaces. The preparation of a dialkyl ester tail first involves the acid-catalyzed condensation of H-Glu-OH with the appropriate fatty acid alcohol to form the dialkyl ester of H-Glu-OH a typical example is shown in Scheme 7. The assembly of peptide-amphiphiles with mono- and dialkyl ester tails is shown in Scheme 8. A series of studies have demonstrated that triple-helical and a-helical protein-like molecular architecture is stabilized in the peptide-amphiphile 44,63-65 ... 

All the characteristics expressed in the biological lipids and phospholipids are also expressed in peptide amphiphiles. A variety of alkyl and dialkyl oligoglutamates will be initially discussed as representative of such molecules, which helped in the determination of the structure/assembly relationship (Figure 7.9). The latest advances that demonstrate how using this knowledge, peptide-derived materials were tailored for the construction of functional nanostructures amphiphiles will also be discussed. 

The structure of donor-acceptor porphyrin complexes such as 68 has very recently been modified to make a new family of amphiphilic porphyrin dyes with polar pyridinium acceptor head groups and hydrophobic dialkyl-aniline donors (Figure 1.34). The free porphyrins and... 

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