Surface-active crown ethers

We recently synthesized several reasonably surface-active crown-ether-based ionophores. This type of ionophore in fact gave Nernstian slopes for corresponding primary ions with its ionophore of one order or less concentrations than the lowest allowable concentrations for Nernstian slopes with conventional counterpart ionophores. Furthermore, the detection limit was relatively improved with increased offset potentials due to the efficient and increased primary ion uptake into the vicinity of the membrane interface by surfactant ionophores selectively located there. These results were again well explained by the derived model essentially based on the Gouy-Chapman theory. Just like other interfacial phenomena, the surface and bulk phase of the ionophore incorporated liquid membrane may naturally be speculated to be more or less different. The SHG results presented here is one of strong evidence indicating that this is in fact true rather than speculation. 

During the past ten years, there have been numerous reports on the synthesis and the application of crown ethers of specific character to various fields. There have been also a few studies of the surface and micellar properties of crown ethers with hydrophobic groups (J - 17). The author has called them surface active crown ethers as a new class of surfactant possessing a promising function (11). 

Surface-active crown ethers are distinctly differ from usual type of nonionics in salt effect on the aqueous properties, due to the selective complexing ability with cations depending on the ring size of the crown. As shown in Figure 3 (22), the cloud point of the crowns is selectively raised by the added salts. This indicates that the degree of cloud point increase is a measure of the crown-complex stability in water (23). 

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],... 

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],... 

Because of the need for basic initiators, cyanoacrylate adhesives do not perform well on acidic surfaces, such as wood. However, the addition of sequestering agents, such as crown ethers [30], 10, or calixarenes [31], 11, and others [32] to the adhesive improves the reactivity of the adhesive on less active surfaces. 

Ikeda, I. Iwaisako, K. Nakatsuji, Y. Okahara, M., (1986) Surface active properties of long chain alkoxymethyl hydroxy crown ethers. Yukagaku 35, 1001 (Chem. Abstr. 106 86714). 

Subsequently, the ion channel activity of 34 was studied using planar bilayer methods.50c Peptide 34 was either introduced to the bulk KC1 solution or mixed with the lipid sample prior to bilayer formation. In the first method, incorporation proved difficult, possibly due to the high tendency of 34 to form aggregates. In the second method the stability of the bilayer was perturbed and single-channels were not obtained. It was postulated that this was due to the adsorption of the peptide onto the surface of the membrane due to electrostatic interactions of the crown ethers with the polar head groups. However as soon as the peptide was incorporated successfully into the bilayer, i.e. peptide parallel to the lipid hydrocarbons, singlechannel events were recorded indicative of 34 functioning in a unimolecular fashion. 

Dendrimers with up to 96 redox-active TTF moieties on the periphery, which allow the generation of polycationic species bearing up to 192 positive charges on the surface, were incorporated into electrodes. These dendrimer-modified electrodes find application in electrochemical sensing of metal cations (i.e., Ba ), thanks to the grafting of crown ether/TTF units on the periphery of dendrimers < 2001AGE224>. 

At high temperature and in the presence of Mo complexes, THF is polymerized to yield crown ethers (scheme 3) [4], Probably, this reaction is responsible for deactivation of the bimetallic catalysts supported on Slbunit. The monometallic catalysts are not deactivated even at high yields of resin complexes and high temperature. It is likely that the polymers do not deposit on the active component and the support surface. 

Reductive alkylation of nitrile by secondary amines having the same or different alkyl chains is another alternative for tertiary amine preparation. Many other special cationics, N-alkyl monoaza crown ethers [53], for example, can be classified as tertiary amines. The surface-active tertiary amine compounds are used as such (as corrosion inhibitors, dopes, antistatics, reagents in mineral processing) or as semifinished products. Alkyldimethylamines and dialkylmethylamines were run on a commercial level, e.g., by Albemarle (former Ethyl Corp.) as ADMA Tertiary Amines and DAMA Tertiary Amines , respectively. 

Use of one-component compositions, including functional groups and crown-ethers, for impregnation. These crown-ethers form complexes with metal atoms located on the surface of the materials being impregnated. The complexes possess catalytic activity and can initiate and accelerate polymerization of the compositions. 

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