Unusual pH-regulated surface adsorption and aggregation behavior of a series of asymmetric gemini amino-acid surfactants

Lv, Jing; Qiao, Wenxiao

doi:10.1039/c5sm00041f

Cited by 26 publications

(24 citation statements)

References 40 publications

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“…Certain cationic gemini surfactants with low toxicity have a superior ability to introduce genes into cells [69][70][71][72]. pH regulation has profound effects on surface adsorption and aggregation behavior of gemini surfactants [73]. Micellar self-assembly of gemini surfactants is the focus of research largely for their potential applications due to their double chains [74].…”

Section: Greenolution Of Industrial Needs By Using Cationic Geminismentioning

confidence: 99%

Review on chemically bonded geminis with cationic heads: second-generation interfactants

et al. 2015

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Cationic gemini surfactants are a special class of second-generation smart surfactants. Since Menger first named them, gemini surfactants have drawn a wide and immense attraction from scientists throughout the whole world. These dimeric surfactants possess two or more hydrophilic with two or more hydrophobic head groups, chemically bonded with a linker, called the spacer group. These kinds of surfactants are used mainly in homogeneous catalytic reactions, as well as for solubilisation, emulsification, and many more technical applications. They are used in industries for electro-decoating, stabilization of adhesive polymer latex, antifriction agents, mining, paper manufacturing, preparation of surfactants including softeners, cosmetics, and most importantly, recent advancement in drug designing, synthesis, and application in medicine. The aim of this paper is to bring attention to the high performance second generation interfactants, with a focus on their synthesis, structure, types, and greener industrial application with high possibility of future prospect.

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Section: Greenolution Of Industrial Needs By Using Cationic Geminismentioning

confidence: 99%

Review on chemically bonded geminis with cationic heads: second-generation interfactants

et al. 2015

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“…5 Because of their special properties, several researchers became interested in asymmetric gemini surfactants. 6−8 …”

Section: Introductionmentioning

confidence: 99%

Organometallic, Nonclassical Surfactant with Gemini Design Comprising π-Conjugated Constituents Ready for Modification

et al. 2018

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Surfactants are functional molecules comprising a water-compatible head group and a hydrophobic tail. One of their features is the formation of self-assembled structures in contact with water, for instance, micelles, vesicles, or lyotropic liquid crystals. One way to increase the functionality of surfactants is to implement moieties containing transition-metal species. Ferrocene-based surfactants represent an excellent example because of the distinguished redox features. In most existing ferrocene-based amphiphiles, an alkyl chain is classically used as the hydrophobic tail. We report the synthesis and properties of 1-triisopropylsilylethynyl-1′-trimethylammoniummethylferrocene (FcNMe3TIPS). In FcNMe3TIPS, ferrocene is part of the head group (Gemini design) but is also attached to a (protected) π-conjugated ethynyl group. Although this architecture differs from that of classical amphiphiles and those of other ferrocene-based amphiphiles, the compound shows marked surfactant properties comparable to those of lipids, exhibiting a very low value of critical aggregation concentration in water (cac = 0.03 mM). It forms classical micelles only in a very narrow concentration range, which then convert into monolayer vesicles. Unlike classical surfactants, aggregates already form at a very low concentration, far beneath that required for the formation of a monolayer at the air–water interface. At even higher concentration, FcNMe3TIPS forms lyotropic liquid crystals, not only in contact with water, but also in a variety of organic solvents. As an additional intriguing feature, FcNMe3TIPS is amenable to a range of further modification reactions. The TIPS group is easily cleaved, and the resulting ethynyl function can be used to construct heterobimetallic platinum-ferrocene conjugates with trans-Pt(PEt3)2X (X = Cl, I) complex entities, leading to a heterobimetallic surfactant. We also found that the benzylic α-position of FcNMe3TIPS is rather reactive and that the attached ammonium group can be exchanged by other substituents (e.g., −CN), which offers additional opportunities for further functionalization. Although FcNMe3TIPS is reversibly oxidized in voltammetric and UV–vis spectroelectrochemical experiments, the high reactivity at the α-position is also responsible for the instability of the corresponding ferrocenium ion, leading to a polymerization reaction.

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“…Amino acid-based surfactants have become increasingly popular in recent years because they are environmentally benign, abundant, and quite versatile [11][12][13][14][15][16][17][18][19]. Surfactants with amino acid head groups have both amide and carboxylic acid functional groups; therefore, solution pH would be expected to affect the percentage ionization of the carboxylate groups and the rate at which amide protons exchange with solvent [19][20][21]. The degree of head group ionization and the amide proton solvent exchange rate would in turn be expected to affect micelle physical properties like CMC, size, and aggregation number [12,22].…”

Section: Introductionmentioning

confidence: 99%

Effect of pH on the Binding of Sodium, Lysine, and Arginine Counterions to l‐Undecyl Leucinate Micelles

Lewis

Hughes

Vasquez

et al. 2016

J Surfact & Detergents

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Micelle formation by the amino acid‐based surfactant undecylenyl l‐leucine was investigated as a function of solution pH with NMR, dynamic light scattering, and fluorescence spectroscopy. NMR and dynamic light scattering showed that 50 mM undecylenyl l‐leucine and 50 mM NaHCO3 solutions contained micelles approximately 20 Å in diameter and that micelle radius and the mole fraction of surfactant molecules associated with micelles changed very little with solution pH. The binding of the amino acids arginine and lysine to the anionic micelles was also investigated from pH 7.0 to 11.5. Below pH 9.0, the mole fraction of arginine cations bound to the micelles was approximately 0.4. Above pH 9.0, the arginine counterions became zwitterionic, and the mole fraction of bound arginine molecules decreased steadily to less than 0.1 at pH 11. When arginine dissociated from the micelles, their radii decreased from 14 to 10 Å. Similar behavior was observed with lysine; however, when lysine dissociated from the micelle surface, little change in micelle radius was observed. Two‐dimensional NMR experiments suggested that below pH 9.0, l‐arginine bound perpendicular to the micelle surface primarily though its side chain amine while l‐lysine bound parallel to the surface through both of its amine functional groups. Finally, the rate at which the amide protons on the surfactant headgoup exchanged with solvent was investigated with NMR spectroscopy. The exchange reaction was faster in solutions containing only surfactant monomers and slower when the surfactants were in micellar form and the headgoup amide protons were less exposed to solvent.

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Unusual pH-regulated surface adsorption and aggregation behavior of a series of asymmetric gemini amino-acid surfactants

Cited by 26 publications

References 40 publications

Review on chemically bonded geminis with cationic heads: second-generation interfactants

Review on chemically bonded geminis with cationic heads: second-generation interfactants

Organometallic, Nonclassical Surfactant with Gemini Design Comprising π-Conjugated Constituents Ready for Modification

Effect of pH on the Binding of Sodium, Lysine, and Arginine Counterions to l‐Undecyl Leucinate Micelles

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