crown ether


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crown ether

[′krau̇n ‚ē·thər]
(organic chemistry)
A macrocyclic polyether whose structure exhibits a conformation with a so-called hole capable of trapping cations by coordination with a lone pair of electrons on the oxygen atoms.
References in periodicals archive ?
It is well known that the extractability of metal ions with macrocylic reagents such as crown ether and cryptand is governed by the stability of the metal complexes [17].
was dispersed in distilled water (~1 / 100, by weight) by stirring overnight in a beaker; then a 1 ~3 % by volume solution of crown ether in acetone (~150 mmol/ 100 g, crown ether/clay) was added slowly to the suspension.
To mimic the active site, macrocyclic compounds such as cyclodextrins [1], crown ether [2], cyclophanes [3]and calixarenes [4], each having an inclusion cavity as a basic skeleton of potent artificial monooxygenase, were usually employed.
When compared to crown ethers and cryptants, calixarenes carry metal cations from one phase to the other more selectively.
This research introduces the use of crown ethers to shield the growing chains from such unwanted interactions.
He also holds a patient on hydroxamic acid crown ethers.
Part F includes Chapters on a New General Method for the Synthesis of O- and S-Glucosides; Chiral Crown Ethers Incorporating D-Glucose; Biomass Production of Industrial Sweet Potato as Influenced by Vesicular Arbuscular Mycorrhizal Fungal Inoculation; Mesta as a Potential Source of Carbohydrate via Organosolv Delignification; Scanning Electron Microscopic Studies of the Surface Texture of Controlled Release Matrices of Carboxymethylcellulose; Study on Thermal Degradation of Ispaghula Esters; Synthesis of Quaternary Ammonium Compounds of Hydroxyethyl Guar Gum as Catalysts for Curing of Epoxy Resins.
Rogers utilizes his diffractometer in separations research to study the structures of metal coordination spheres in inorganic complexes with crown ethers and polyethylene glycols.
MeasurementsBuschmann's methodA spectrophotometric method to determinethe complex stability constants of the ammonium and alkylammonium ions with many of dibenzo crown ethers in aqueous solution was developed by K= [LM ] [L] [Mn+] (2) Buschmann [17].
These consisted of helixes with polar crown ethers to act as the "jumping points" for the ions.