Crown ethers in hydrogenated graphene

2021 ◽  
Author(s):  
Kai Guo ◽  
Sitong Liu ◽  
Haoming Tu ◽  
Zhikun Wang ◽  
Liang Chen ◽  
...  
Keyword(s):  
Crown Ether ◽  
Crown Ethers ◽  
Hydrogenated Graphene ◽  
High Flexibility

Crown ethers could serve as hosts to selectively incorporate various guest atoms or molecules within the macrocycles. However, the high flexibility of crown ether molecules limits their applications in areas...

1,8-Dioxyanthracene-Derived Crown Ethers: Synthesis, Complexation with Paraquat and Assembly of a Tetracationic Cyclophane-Crown Ether Based [2]Catenane

2014 ◽  
Vol 2014 (31) ◽  
pp. 6925-6934 ◽  
Author(s):  
Bo Tang ◽  
Hong-Mei Yang ◽  
Wen-Jing Hu ◽  
Ming-Liang Ma ◽  
Yahu A. Liu ◽  
...  
Keyword(s):  
Crown Ether ◽  
Crown Ethers

ChemInform Abstract: Synthesis of Two 1,3-2,4-Calix[4]bis-crown Ethers Containing Two 1,2-Phenylene and One Pyridine or Anisole Units in Each Crown Ether Moiety.

ChemInform ◽  
2010 ◽  
Vol 31 (25) ◽  
pp. no-no
Author(s):  
Guo-Ping Xue ◽  
Jerald S. Bradshaw ◽  
Ning Su ◽  
Krzysztof E. Krakowiak ◽  
Paul B. Savage ◽  
...  
Keyword(s):  
Crown Ether ◽  
Crown Ethers ◽  
Crown Ether Moiety

Polycarboxylate crown ethers from meso-tartaric acid

1991 ◽  
Vol 69 (1) ◽  
pp. 12-19 ◽  
Author(s):  
Frank R. Fronczek ◽  
Richard D. Gandour ◽  
Thomas M. Fyles ◽  
Philippa J. Hocking ◽  
Susan J. McDermid ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Crown Ether ◽  
Tartaric Acid ◽  
Crown Ethers ◽  
Nmr Spectra ◽  
Product Distribution ◽  
Complexing Agents ◽  
Triclinic Space Group ◽  
The Stability ◽  
Ether Synthesis

The synthesis of crown ethers derived from meso-tartaric acid was investigated. The sodium salt of the bis(dimethylamide) of meso-tartaric acid reacted with diethylene glycol ditosylate to give a mixture of 18-crown-6 tetraamide and 27-crown-9 hexaamide crown ethers. The 2R,3S,11S,12R 18-crown-6 isomer crystallized in triclinic space group [Formula: see text] (a = 7.557(2), b = 8.866(2), c = 10.4133(13) Å, α = 94.13(2), β = 95.86(2), γ = 99.26(2)°, R = 0.040 for 2090 observed of 3129 unique reflections). The structures of the remaining products were then assigned from the NMR spectra. The solution conformations of the amide crown ethers were examined by NMR, and provide a rationale for the product distribution obtained. One of the 18-crown-6 isomers and a mixture of the two 27-crown-9 isomers were hydrolyzed to the respective crown ether carboxylic acids, and the stability constants for complexation of cations were determined by potentiometric titration. The meso tetra- and hexacarboxylates are remarkably nonselective and inefficient cation complexing agents, compared to related crown ethers from R,R-(+)-tartaric acid, due to the unfavorable conformational control exerted by the tartaro units. Key words: crown ether synthesis, complexation, crown ether conformation, meso-tartaric acid, crystal structure.

scholarly journals Flat Crown Ethers with Planar Tetracoordinate Carbon Atoms

2020 ◽  
Author(s):  
Venkatesan Thimmakondu ◽  
Krishnan Thirumoorthy
Keyword(s):  
Carbon Atom ◽  
Crown Ether ◽  
Crown Ethers ◽  
In Silico ◽  
Alkaline Earth ◽  
Experimental Studies ◽  
Building Blocks ◽  
Binding Energies ◽  
High Symmetry ◽  
Structural Rigidity

Novel flat crown ether molecules have been characterized in silico using DFT hybrid and hybrid-meta functionals. Monomer units of Si2C3 with a planar tetracoordinate carbon atom have been used as building blocks. Alkali (Li+, Na+, K+, Rb+, and Cs+) and alkaline-earth (Ca2+, Sr2+, and Ba2+) metals, and uranyl (UO2+ 2 ) ion selective complexes have also been theoretically identified. The high symmetry and higher structural rigidity of the host molecules may likely to impart higher selectivity in chelation. Theoretical binding energies have been computed and experimental studies are invited.

scholarly journals Extraction of short-lived zirconium and hafnium isotopes using crown ethers: A model system for the study of rutherfordium

2006 ◽  
Vol 94 (3) ◽  
Author(s):  
Ralf Sudowe ◽  
M.G. Calvert ◽  
Ch. E. Düllmann ◽  
L. M. Farina ◽  
C. M. Folden ◽  
...  
Keyword(s):  
Crown Ether ◽  
Crown Ethers ◽  
Ion Association ◽  
Extraction Yield ◽  
Chloro Complex ◽  
Acid Media ◽  
Hafnium Isotopes ◽  
Group 4 ◽  
Extraction Behaviour ◽  
Hydrochloric Acid Media

SummaryThe extraction of zirconium and hafnium from hydrochloric acid media was studied using the crown ethers dibenzo-18-crown-6 (DB18C6), dicyclohexano-18-crown-6 (DC18C6) and dicyclohexano-24-crown-8 (DC24C8) as extractants. The goal was to find an extraction system that exhibits a high selectivity between the members of group 4 of the periodic table and is suitable for the study of rutherfordium. It was found that Zr and Hf are both extracted using DB18C6, DC18C6 and DC24C8. The extraction yield increases with increasing acid concentration and increasing concentration of crown ether. The extracted species most likely consists of an ion-association complex formed between a Zr or Hf chloro complex and a hydronium crown ether complex. Conditions can be found for each extractant that provide for the separation of Zr from Hf. This selective separation between Zr and Hf makes the extraction with crown ethers from HCl well suited to study the extraction behaviour of Rf and compare it to the behaviour of Zr and Hf. These extraction systems can be used to determine whether the extraction behaviour of Rf is similar to Zr, similar to Hf or follows the trend established by the lighter homologs. The extraction kinetics are fast enough for the study of the 78-s isotope

scholarly journals Surface Engineering of Fluoropolymer Films via the Attachment of Crown Ether Derivatives Based on the Combination of Radiation-Induced Graft Polymerization and the Kabachnik–Fields Reaction

Polymers ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1337 ◽  
Author(s):  
Omichi ◽  
Yamashita ◽  
Okura ◽  
Ikutomo ◽  
Ueki ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Crown Ether ◽  
Crown Ethers ◽  
Graft Polymerization ◽  
Surface Engineering ◽  
Ammonium Cation ◽  
Three Component Reaction ◽  
Radiation Induced ◽  
Fluoropolymer Films

In this manuscript, we present the successful attachment of crown ether moieties onto fluoropolymer surfaces, via the combination of radiation-induced graft polymerization and a subsequent surface Kabachnik–Fields three-component reaction. The obtained crown ether-tethered fluoropolymer films exhibited an ammonium cation capturing ability, owing to the host–guest interactions (i.e., hydrogen bonding) between the surface-anchored crown ethers and the guest ammonium cations.

ChemInform Abstract: Investigations in the Crown Ether Series. Part 3. Catalytic Activity of Crown Ethers and Their Immobilized Analogues.

ChemInform ◽  
1988 ◽  
Vol 19 (28) ◽  
Author(s):  
N. I. ABAKUMOVA ◽  
I. P. KOLENKO ◽  
L. A. PETROV ◽  
A. A. NOVOSELOVA ◽  
L. M. GUS'KOVA
Keyword(s):  
Catalytic Activity ◽  
Crown Ether ◽  
Crown Ethers

Newly synthesized tetraoxa-diaza crown ether derivatives versus commercialized crown ethers in the separation of positional isomers with capillary electrophoresis

2006 ◽  
Vol 41 (4) ◽  
pp. 1164-1170 ◽  
Author(s):  
Peter Forlay-Frick ◽  
Debby Mangelings ◽  
Tímea Iványi ◽  
István Lázár ◽  
Károly Héberger ◽  
...  
Keyword(s):  
Capillary Electrophoresis ◽  
Crown Ether ◽  
Crown Ethers ◽  
Positional Isomers
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