Compounds amphiphilic

Iwahashi M, Kikuchi K, Achiba Y, Ikemoto I, Araki T, Mochida T, Yokoi S-l, Tanaka A and Iriyama K 1992 Morphological study ofthin-film systems of pure fuiierene (Cgg) and some other amphiphilic compounds on the electron microscopic scale Langmuir 8 2980-4... 

The so-called self-assembly technique has its origin in 1946, when a paper was published by Bigelow et a] [116] and tluis is slightly younger tlian tlie LB teclmique. The autliors noted tliat a hydrophilic surface exposed to an amphiphilic compound dissolved in a non-polar solvent induces tlie amphiphilic material to fonn a monolayer on it. 

A microemulsion (p.E) is a thermodynamically stable, transparent (in the visible) droplet type dispersion of water (W) and oil (O a saturated or unsaturated hydrocarbon) stabilized by a surfactant (S) and a cosurfactant (CoS a short amphiphile compound such as an alcohol or an amine) [67]. Sometimes the oil is a water-insoluble organic compound which is also a reactant and the water may contain mineral acids or salts. Because of the small dispersion size, a large amount of surfactant is required to stabilize microemulsions. The droplets are very small (about 100-1000 A [68]), about 100 times smaller than those of a typical emulsion. The existence of giant microemulsions (dispersion size about 6000 A) has been demonstrated [58]. 

All the fullerene-containing dendrimers reported to date have been prepared with a Cgo core but never with fullerene units at their surface or with Cgg spheres in the dendritic branches. We have recently started a research program on the synthesis of dendrons substituted with fullerene moieties. These fulleroden-drons are interesting building blocks for the preparation of monodisperse fullerene-rich macromolecules. In addition, they are also amphiphilic compounds capable of forming stable Langmuir films at the air-water interface. 

Micelles the mostly spherical nanoscale aggregates formed by amphiphilic compounds above their critical micelle concentration in aqueous solution have a narrow size distribution and are dynamic, because there is a fast exchange of amphiphiles in solution and those incorporated in micelles. However, micelles are defined as self-assembled structures, since the structure is in thermodynamical equilibrium. 

These emerging structural requirements of enhancement have launched a quest for new, even more powerful enhancers. Several potent amphiphilic compounds have surfaced from this pursuit that, at their worst, are only mildly tissue provocative, key examples... 

Fatty alcohol and fatty acid ethoxylates are amphiphilic compounds that are commonly used as nonionic surfactants and emulsifiers in many applications, such as cosmetic and care products and in textile fabrication. They serve as antistatic lubricants and viscosity regulators. 

The cardanyl glycolipids behave as amphiphilic compounds and are able to self-assemble in water to form twisted fibers, helical coils, and high axial ratio nanotubes... 

The most plausible components are amphiphilic compounds. Growth occurs by means of chemical transformation of simple molecules into amphiphilic species. 

D. W. Deamer and J. P. Dworkin have reported in detail on the contribution of chemistry and physics to the formation of the first primitive membranes during the emergence of precursors to life the authors discussion ranges from sources of amphiphilic compounds, growth processes in protocells, self-organisation mechanisms in mixtures of prebiotic organic compounds (e.g., from extracts of the Murchison meteorite) all the way to model systems for primitive cells (Deamer and Dworkin, 2005). 

Liquid crystalline phases1 can be divided into two classes thermotropic phases are obtained by temperature variations and exist in a limited temperature interval (see Figure 7.1) lyotropic phases are instead formed by mixing two or more substances, for example, water and amphiphilic compounds or polymers and a solvent. Especially for amphiphilic compounds in water, temperature may play a role in determining the phase behavior. 

Amphiphilic compounds and other chemicals used are shown in Figs. 5 [3,4] and 6 [36] together with their abbreviations. The synthetic procedures for A-S-D triad, A-S dyad, and H light harvesting antenna molecules in Fig. 5 were described previously [3,37,38]. A cationic cyanine dye with two long alkyl chains (CD) in Fig. 5 was purchased from Japanese Research Institute for Photosensitizing Dyes,... 

Okayama, Japan. The synthetic procedures for S-D dyads and their reference compounds shown in Fig. 6 are illustrated in Fig. 7, where a naphthalene and a ferrocene moiety are used as an S and a D moiety, respectively. For comparison of photoinduced electron transfer rates between a single alkyl chain and a triple alkyl chain as the spacers of the S-D dyads with the same length of four-carbons, S-D dyads with a rigid spacer with a bicyclo[2.2.2]octane were synthesized [39]. The synthetic procedure for the S-D dyads with the rigid spacer is also shown in Fig. 8 [39], Other amphiphilic compounds and chemicals were commercially available. 

Figure 5. Structural formulae of amphiphilic compounds and other chemicals used for photo-electric conversion and their abbreviations.

R. Fabios, M.D. Sicilia, S. Rubio and D. Perez-Bendito, Surfactant to dye binding degree-based methodology for the determination of ionic amphiphilic compounds. Anal. Chem., 75 (2003)6011-6016. 

Surfactant molecules (also called amphiphiles or detergents) combine a polar or ionic head and a non-polar tail within the same molecule. The non-polar part, which is typically made up of one or more alkyl chains, causes these compounds to be sparingly soluble in water, whereas the polar or ionic part interacts strongly with water. Upon increasing the concentration of the amphiphilic compound in water, the solubility limit will be reached at a certain point and phase separation will set in. Due to the efficient interactions between the polar headgroups and the surrounding water molecules, a complete phase separation is usually unfavourable. Instead, the process halts in an intermediate stage... 

Figure 1 Schematic structures of micelle and liposome, their formation and loading with a contrast agent, (a) A micelle is formed spontaneously in aqueous media from an amphiphilic compound (1) that consists of distinct hydrophilic (2) and hydrophobic (3) moieties. Hydrophobic moieties form the micelle core (4). Contrast agent (asterisk gamma- or MR-active metal-loaded chelating group, or heavy element, such as iodine or bromine) can be directly coupled to the hydrophobic moiety within the micelle core (5), or incorporated into the micelle as an individual monomeric (6) or polymeric (7) amphiphilic unit, (b) A liposome can be prepared from individual phospholipid molecules (1) that consists of a bilayered membrane (2) and internal aqueous compartment (3). Contrast agent (asterisk) can be entrapped in the inner water space of the liposome as a soluble entity (4) or incorporated into the liposome membrane as a part of monomeric (5) or polymeric (6) amphiphilic unit (similar to that in case of micelle). Additionally, liposomes can be sterically protected by amphiphilic derivatization with PEG or PEG-like polymer (7) [1].

Fontell, K., Mandell, L, and Ekwall, P., Some isotropie mesophases in systems containing amphiphilic compounds, cta Chem. Scand., 22 3209 (1968). 

P. Winsor, "Solvent Properties of Amphiphilic Compounds," Butterworth Sci. Publ., London, 1954. 

Danes , P. R. Proc. ISEC 86, Munich DECHEMA, 1986 527-535 pp. Pabby, A. K. Sastre, A-M. Ion Exchange and Solvent Extraction, Marcus, Y. and Sengupta, A. K. Eds., Marcel Dekker New York, 2002 vol. 15, 331 69. Winsor, P. A. Solvent Properties of Amphiphilic Compounds, Butterworth Scientific London, 1954. 

More recently, micelles have also been proposed as contrast agents. They are colloidal particles with a hydrophobic core and a hydrophilic shell, formed by amphiphilic compounds 102). 

From the beginnings of imino sugar research and application, such lipophilic modifications as AA alkyl derivatives of 1-deoxynojirimycin and its relevant epimers have been prepared and their properties investigated. These amphiphilic compounds... 

The most elusive of self-aggregation processes is presented by the so-called hydrotropes amphiphilic compounds with the hydrophobic moiety being typically too small to induce micelle formation. Examples of hydro tropes are butylmonogly cosulfate (BMGS),/7-toluenesulfonate (PTS), and cumenesulfonate (CS) (Scheme 1). 

Scheme 11 Amphiphilic compounds by ring-opening of aldonolactones...

Perfluorocarbons bearing a polar hydrophilic head are very active surfactants. Indeed, the presence of fluorine atoms strongly lowers the critical micelle concentration (CMC) of an amphiphilic compound. Moreover, fluorination generally has important effects on micellization phenomena, especially on the size and shape of formed micelles. 

Winsor P (1954) Solvent Properties of Amphiphilic Compounds. Butterworth, London... 

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