Macrocyclic surfactants

Conventional SERS substrates typically have disordered nanoscale features, such as that found in electrochemically roughened Au or Ag surfaces.170 SERS substrates can also be rationally designed by lithography, by self-assembly, or a combination of the two. Both supramolecular and nanoscale self-assembly methods can be used to fabricate two-dimensional Au nanoparticle arrays with tunable optical properties.33 171172 For example, macrocyclic surfactants based on resorcinarenes (a subclass... 

Ru(bipy)2 a nd pyrene. In all those cases no hack reaction between oxidized donor and Ag is observed. Apparently, through electrostatic interactions, the donor cation is ejected from the positively charge aggregates before back electron transfer can take place. Once in the aqueous phase, the reentry of in the micelle is prevented by the repulsive surface charge. We conclude that in the photoinduced reduction of Ag" " to silver atoms the fimctional macrocyclic surfactant serves three important purposes through high local concentration of the acceptor one accelerates drastically the forward rate - and hence the yield - of reaction the Ag atom is stabilized by the macro-cyclic ligand and finally, the back electron transfer prevented by the microscopic electrostatic barrier provided by the lipid/water interface. 

In summary, it can be stated that for screening approaches in CE, only CD derivatives have been used. Other chiral selectors occasionally applied in CE, such as crown ethers, macrocyclic antibiotics, and chiral surfactants [39], were not found to be involved in (generic) screening approaches for chiral separations. 

Based on the theory, the separation of enantiomers requires a chiral additive to the CE separation buffer, while diastereomers can also be separated without the chiral selector. The majority of chiral CE separations are based on simple or chemically modified cyclodextrins. However, also other additives such as chiral crown ethers, linear oligo- and polysaccharides, macrocyclic antibiotics, chiral calixarenes, chiral ion-pairing agents, and chiral surfactants can be used. Eew non-chiral separation examples for the separation of diastereomers can be found. 

The Diels-Alder reaction is an important and widely used reaction in organic synthesis (Sauer and Sustmann, 1980), and in the chemical industry (Griffiths and Previdoli, 1993). Rate enhancement of this reaction has been achieved by the use of solvents such as water, surfactants, very high pressure, lithium amides, alkylammonium nitrate salts, and macrocyclic hosts (Sherman et ak, 1998). Diels-Alder reactions can be ran in neutral ionic liquids (such as 1-butyl-3-methylimidazolium trifluoromethanesulfo-nate, l-butyl-3-methylimidazolium hexafluorophophate, l-butyl-3-methylimidazolium tetrafluoroborate, and l-butyl-3-methylimidazolium lactate). Rate enhancements and selectivities are similar to those of reactions performed in lithium perchlorate-diethyl ether mixtures. 

Nevertheless, pendant arm derivatives of [9]aneN3 and other polyaza-macrocycles have garnered great interest in recent years for their use in many different chemical applications such as catalysis [24-30], selective cation binding [30-32], surfactants [33, 34], mimicry of enzymes and siderophores [35-39], tumor-directed radioisotope carriers, and use in magnetic resonance imaging reagents [40],... 

Kuwamura, T. Yoshida, S., (1980) Surface-active crown ethers. 2. Synthesis, surfactant properties, and catalytic action of macrocyclic polyethers possessing a 4-alkyl-l,3,5-triazine subunit Nippon Kagaku Kaishi 427 [Chem. Abstr. 493 28168e],... 

Pendant donor macrocycles have heen investigated as a basis for producing cationic surfactants. The potential hgands 86-90 can easily be produced in an elegant two-step synthesis starting from 84 (93, 94). 

Experimentally, the macrocyclic trichothecenes satra-toxin G, isosatratoxin F, and roridin A have been shown to cause nasal and pulmonary toxicity when administered intranasally or intratracheally to mice. Intranasal exposure of satratoxin G and roridin A induced apoptosis of olfactory sensory neurons resulting in atrophy of the olfactory epithelium and olfactory nerve layer of the olfactory bulb in the frontal brain (Islam et al, 2006, 2007). Alveolar-type II cells and alveolar macrophages were injured following intratracheal instillation of isosatratoxin F or Stachybotrys spores with marked changes in surfactant synthesis and secretion (Rand et al, 2002). 

Biehl MP, Izatt RM, Lamb JD, and Christensen JJ. Use of a macrocyclic crown ether in an emulsion (Uquid surfactant) membrane to effect rapid separation of Pb from cation mixtures. Sep Sci Technol 1982 17 289-294. 

Tang J and Wai CM. Transport of trivalent lanthanides through a surfactant membrane containing an ionizable macrocyclic polyether. J Membr Sci 1989 46 349-356. 

Other spectrophotometric organic reagents used for the determination of silver include 2-(3,5-dibromo-2-pyridylazo)-5-diethylaminophenol (3,5-diBr-PADAP) in the presence of the anionic surfactant lauryl sulphate (e = 7.7-10 ) [43] and dodecyl sulphate (e = 6-10 ) [44], 4-(3,5-dibromo-2 pyridylazo)-V,V-diethylaniline in the presence of dodecyl sulphate [45], Cadion 2B in the presence of Triton X-100 (e = 1.0-10 ) [46], 4-(2-quinolylazo)phenol [47], 4-(p-nitrophenylazo)-l-amino-3-pyridynol (e = 1.07-10 at 605 nm) [48], and thyrodine (after extraction of silver with the use of macrocyclic compounds) [5,49]. 

Second group is water-immiscible primary, secondary, tertiary amines, and their derivatives, quaternary amine salts and other proton acceptors (see respective chapters). Considerable effort has been devoted to the development of anion transporting agents, playing an important role in the biological and biochemical processes. Several amines, their derivatives, surfactants, lipophilic metal complexes, macrocycles with positively charged subunits are known and developing as anion carriers [22-24, 27-29, 44-46]. 

Macrocyclic compounds with a paraffinic chain have first been described by Cinquini et al.107). In aqueous solution they form readily micelles with CMC values ranging between 10-5 and 10-3 M depending on the exact nature of the head group and the chain length168,169). Crown ether surfactants are particularly suited to serve as electron relays in redox events since different metal ions covering a wide range of standard potentials may be inserted into the macrocyclic ring. Consider, for example, the crown 5-n-tetradecyl-... 

---