Crown ethers amphiphilic

Shinkai and coworkers prepared numerous novel amphiphilic crowns (Shinkai, 1990) and incorporated them into membranes, formed membranes from them, or used them in liquid crystalline assemblies to control properties (He et al., 1990). Interest in this area continues. Four chiral amphiphilic crown ethers were recently reported that recognize enantiomeric amino acids when examined as Langmuir films (Badis et al., 2004). Finally, it is interesting to note that liposomes formed from amphiphiles (e.g., crown ethers) having neutral headgroups (i. e., niosomes) have been studied as drug delivery vehicles (Uchegbu and Vyas, 1998). 

Badis, M. Tomaszkiewicz, I. Joly, J.-P. Rogalska, E., (2004) Enantiomeric recognition of amino acids by amphiphilic crown ethers in langmuir monolayers Langmuir 20, 6259-6267. 

Furusawa, K. Obata, C. Matsumura, H. Takeuchi, M. Kuwamura, T., (1990) Bilayer membranes of amphiphilic crown ethers with amino acid residue Chem. Lett. 1047-1050. 

Ikeda, I. Tsuji, T. Okahara, M., (1988) Synthesis of amphiphilic crown ethers and their ability to form molecular aggregation film. Kenkyu Hokoku - Asahi Garasu Kogyo Gijutsu Shoreikai 53, 311-315 [Chem. Abstr. 112 98500],... 

Amphiphilic macrocyclic host molecules have been investigated for many years. Among others, it is known that amphiphilic crown ethers, " cryptands, calixarenes, cyclodextrins, and curcubitnrils can form bilayer vesicles in aqueous solution. However, the host-guest chemistry of such host vesicles remained largely unexplored for many years. Darcy and Ravoo prepared bilayer vesicles composed entirely of amphiphilic cyclodextrin host molecules. These vesicles have a membrane that displays a high density of embedded host molecules that bind hydrophobic guest molecules such as f-butylbenzyl and adamantane derivatives. The characteristic size-selective inclusion behavior of the cyclodextrins is maintained, even when the host molecules are embedded in a hydrophobic... 

A benzo[18]crown-6 adduct (72) of Cgg (not shown) has been synthesized by the addition of the corresponding o-quinodimethane 71 in toluene [58]. The solubility of 72 in pro tic solvents such as MeOH strongly increases after the complexation of ions, as shown by extraction experiments. The combination of the crown ether and the fullerene moiety in 72 provides a highly amphiphilic character. This behavior allowed the preparation of Langmuir-Blodgett films of monolayers on mica of 72 and its complex. 

Figure 11.40 (Left) Stmcture of the Pao et al. s (2001) amphiphilic monodendron and the space-filling model showing a possible conformation at the water-air interface. (Right) The chains are assumed to extend vertically away from the water surface, and the crown ether group is assumed to extend into the water. Reprinted from Pao et al. (2001). Copyright 2001 American Chemical Society.

Delmau et al. (129) studied the self-association of fluorinated alcohols used as diluent modifiers for the selective extraction of cesium from caustic media by calixarene-crown ethers. They found that the salt distribution ratio is enhanced by the modifiers and explained this by a solubilization effect of the modifier due to its amphiphilic properties. 

Ikeda, I. Takayuki, K. Tanaka, K. Takeda, T. Kurosawa, H. Okahara, M., (1990) Synthesis and vesicleforming ability of an amphiphilic compounds composed of a single lipophilic chain and a crown ether ring as a hydrophilic moiety. Nippon Kagaku Kaishi 1059-1064 [Chem. Abstr. 114 26193],... 

Inokuma, S. Ito, D. Kuwamura, T., (1988) Surface active crown ethers. XII. Synthesis and properties of amphiphilic monoazacrown ethers possessing a hydroxyl group in the side chain Yukugaku 37, 441-446 [Chem. Abstr. 109 131255],... 

Munoz, S. Mallen, J. V. Nakano, A. Chen, Z. Echegoyen, L. Gay, I. Gokel, G. W., (1992) Lariat ether bola-amphiphiles formation of crown ether based bola-amphisomes Chem. Commun. 520-522. 

A new family of crown-ether-based bolaamphiphiles, 21, that aggregate into a previously unknown type of bolaamphisome was prepared by Gokel and coworkers [50]. Evidence was presented on vesicle formation from the aqueous suspension of such bolaform amphiphiles. Several reports describing the synthesis of various macrocyclic models related to archael compounds have also appeared in the literature [51]. Fyles et al. prepared a novel series of asymmetric bis-macrocyclic bolaphiles, 22, and evaluated their transport activities in vesicles and planar bilayer membranes [52]. 

Langmuir films of rod-shaped amphiphilic ionophores 9 with laterally grafted crown ether units of different ring size (n = 1—3) have been successfully exploited to investigate alkali metal ion molecular recognition processes at the air-water interface <1998L5245>. 

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