Ionic liquids amphiphiles

Intrinsic to ionic surfactants and amphiphiles are solvophihc (or ionophilic) groups. We were therefore interested in learning whether the simple dialkylammonium bromides (2C,jN, n = 12, 14 Figure. d) that belong to the original family of synthetic bilayer membranes [10] form a bilayer in ionic liquids. Amphiphiles 2C N" were dispersed in three ionic hquids (Schemes 11.1-11.2) by ultrasonication (concentrations, 10 mM). While 2C12N+ as homogeneously dispersed in the conventional... 

D NOESY NMR spectroscopy were used to examine the manner in which ionic liquid amphiphile self-assembles with an ionic surfactant in solution. ... 

Singh, K Marangoni, D. G. Quinn, J. G. Singer, R. D. (2009). Spontaneous vesicle formation with an ionic liquid amphiphile. /. Colloid Interface Sci., 335,105-111. 

Jiao, J., et al., Decorating multi-watted carbon nanotubes with Au nanoparticles by amphiphilic ionic liquid self-assembly. Colloids and Surfaces A Physicochemical and Engineering Aspects, 2012. 408 p. 1-7. 

Sirieix-Plenet, ]., Gaillon, L., and Letellier, R, Behaviour of a binary solvent mixture constituted by an amphiphilic ionic liquid, l-decyl-3-methylimidazolium bromide and water. Potentiometric and conductimetric studies, Talanta, 62, 979,... 

Bowers, J., Vergara-Gutierrez, M. C., and Webster, J. R. R, Surface ordering of amphiphilic ionic liquids, Langmuir, 20, 309-312, 2004. 

The lyophilization of enzymes from solutions containing salts or amphiphilic compounds is known to increase the activity in organic media by up to several orders of magnitude. Thus, the transesterification activity of a-chymotrypsin was increased 82-fold by co-lyophilization with pentaglyme [75]. The colyophilization of lipases and (poly ethylene)glycol (PEG) led to an enhanced transesterification activity in various ionic liquids [76, 77]. 

Cook, A. G., Baumeister, U., Tschierske, C., Supramolecular dendrimers Unusual mesophases of ionic liquid crystals derived from protonation of DAB dendrimers with facial amphiphilic carboxylic acids. J. Mater. Chem. 2005, 15, 1708-1721. 

Unlike the conventional ionic liquid 3, both of the amphiphiles were homogeneously dispersed in the ether-containing ionic liquids and gave translucent dispersions. The 2Ci2N" showed an endothermic peak at 52°C (AH, 18.0 kJ moP AS, ... 

It should be now be clear that the molecular assembly in ionic liquids is governed by (1) the balance of ionophilicity and ionophobicity of the constituent molecules and (2) the chemical structure of the ionic liquids. It may well be that an increase in intermolecular interactions in the bilayer-forming amphiphiles makes their... 

Clearly, there are some similarities between the structural features of ionic liquids and those displayed by some amphiphilic molecules, namely ionic surfactants. 

Greavesa TL, Drummond CJ (2008) Ionic liquids as amphiphile self-assembly media. Chem Soc Rev 37 1709 1726... 

Liquid crystal phases, or mesophases, are characterized by a partial order, intermediate between the full orientational and translational disorder of the isotropic liquid phase and the full orientational and translational order of the crystalline phase. Thermotropic liquid-crystal phases are obtained for a given compound (or possibly a mixture) as a function of temperature, while the so-called lyotropic liquid-crystal phases are obtained as a function of the concentration of a given solute in a solvent Typical examples of the latter systems are the various types of aggregates formed by amphiphilic molecules either in water or in organic solvents. In this chapter we will be interested only in thermotropic systems. An interesting review on lyotropic ionic liquid crystals can be found in Ref. [2],... 

Li W, Zhang J, Li B et al (2009) Branched quaternary ammonium amphiphiles nematic ionic liquid crystals near room temperature. Chem Commun 35 5269-5271... 

Other important biphasic concepts are based on the use of room-temperature ionic liquids (cf. Section 7.3) and, more recently, supercritical C02 (cf. Section 7.4) [31]. In addition, the second phase needs not necessarily to be another solvent. An amphiphilic approach can also be based on the use of micellar systems or vesicles formed by surfactants (cf. Section 4.5). A properly functionalized ligand itself can also function as the surfactant (cf. Section 3.2.4), which can even result in the formation of very stable aggregates [32]. 

Last but not least, the success of aqueous-phase catalysis has drawn the interest of the homogeneous-catalysis community to other biphasic possibilities such as or-ganic/organic separations, fluorous phases, nonaqueous ionic liquids, supercritical solvents, amphiphilic compounds, or water-soluble, polymer-bound catalysts. As in the field of aqueous-phase catalysis, the first textbooks on these developments have been published, not to mention Job s book on Aqueous Organometallic Catalysis which followed three years after our own publication and which put the spotlight on Job s special merits as one of the pioneers in aqueous biphasic catalysis. Up to now, most of the alternatives mentioned are only in a state of intensive development (except for one industrial realization that of Swan/Chematur for hydrogenations in scC02 [2]) but other pilot plant adaptations and even technical operations may be expected in the near future. 

The concept of the dual templating method was further extended by Zhou et al. [131], who introduced amphiphilic ionic liquids (AILs) as structuredirecting agents. The use of l-hexadecyl-3-methylimidazolium chloride as AIL provides the following advantages. It structures the silica walls around the macropores of the inverse opal in a highly ordered, microporous lamellar fashion. The interlayer periodicity of the lamellae is about 2.7 nm, with ca. 

The most severe dra wback in homogeneous catalysis is the separation of the catalyst from the reaction mixture. The industrial success of the aqueous two-phase hydroformylation ofpropene to n-butanal [1] in Ruhrchemie AG in 1984 represents the considerable progress in this field. However, aqueous/organic biphasic catalysis has its limitations when the water solubility of the starting materials proves too low, as in hydroformylation of higher olefins (see Chapter 1). To solve this issue, a variety of approaches have been attempted. Additions of co-solvents [2] or surfactants [3, 4] to the system or application of tenside ligands [5, 6] and amphiphilic phosphines [7, 8] are ways to increase the reaction rates. Other approaches such as fluorous biphase system (FBS see Chapter 4) [9], supported aqueous phase catalysis (SAPC see Section 2.6) [10], supercritical CO2 (cf. Chapter 6) [11] and ionic liquids (cf Chapter 5) [12] have also been introduced to deal with this problem. 

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