نتایج جستجو برای: 18- and 24-Crown ethers

تعداد نتایج: 16918122  

Journal: :iranian journal of chemistry and chemical engineering (ijcce) 1996
mojtaba shamsipour abolfazl semnani

the complexation reactions between tl+ and pb2+ ions and crown ethers 12-crown-4(12c4), 15-crown-5 (15c5), benzo-15-crown-5 (b15c5), 18-crown-6 (18c6), dicyclohexyl-18-crown-6 (dc18c6) and aza-18-crown-6 (a18c6) were studied in 90% acetonitrile and 90% ethanol solutions at 25 °c, using an a.c. polarographic technique. the stoichiometry and stability of the complexes were determined by monitorin...

Journal: :Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy 2006
Marcin Dułak Rémi Bergougnant Katharina M Fromm Hans R Hagemann Adeline Y Robin Tomasz A Wesołowski

Experimental (IR and Raman) and theoretical (Kohn-Sham calculations) methods are used in a combined analysis aimed at refining the available structural data concerning the molecular guests in channels formed by stacked dibenzo-18-crown-6 (DB18C6) crown ether. The calculations are performed for a simplified model comprising isolated DB18C6 unit and its complexes with either H2O or H3O+ guests, w...

Journal: :Molecules 2009
Andrey G Vendilo Dmitry I Djigailo Svetlana V Smirnova Irina I Torocheshnikova Konstantin I Popov Vladimir G Krasovsky Igor V Pletnev

The pH-profiles of the extraction of Cs(+) into four conventional (1-butyl-3-methylimidazolium hexafluorophosphate and bis[trifluoromethyl)sulphonyl]imides of 1-butyl-3-methylimidazolium, 1-hexyl-3-methylimidazolium, and 1-(2-ethylhexyl)-3- methylimidazolium) and two novel (trioctylmethylammonium salicylate and tetrahexylammonium dihexylsulfosuccinate) room temperature ionic liquids have been d...

Journal: :Analytical sciences : the international journal of the Japan Society for Analytical Chemistry 2010
Hiroyuki Okamura Naoki Hirayama Kotaro Morita Kojiro Shimojo Hirochika Naganawa Hisanori Imura

The synergistic effect of 18-crown-6 derivatives, such as 18-crown-6 (18C6), cis-dicyclohexano-18-crown-6 (DC18C6) and dibenzo-18-crown-6 (DB18C6), on the extraction of trivalent lanthanoids (Ln(3+)) into an ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, with 2-thenoyltrifluoroacetone (Htta) was investigated. The extractability of lighter Ln(3+) was enhanced by ad...

2011
Fabian Mutzbauer Nikolaus Korber

The crystal structure of the title compound, [Rb(C(12)H(24)O(6))](3)[Sb(7)]·4NH(3), fills the gap between the already known Zintl anion ammoniates {[Cs(18-crown-6)](3)Sb(7)}(2)·9NH(3) [Wiesler (2007 ▶). Dissertation, Universität Regensburg, Germany] and [K(18-crown-6)](3)Sb(7)·4NH(3) [Hanauer (2007 ▶). Dissertation, Universität Regensburg, Germany]. As in the two known compounds, the anti-mony ...

Journal: :iranian journal of chemistry and chemical engineering (ijcce) 2007
massoumeh parinejad mohammad reza yaftian

crown ethers 12-crown-4 (12c4), benzo-15-crown-5 (b15c5), 18-crown-6 (18c6), nitrobenzo-18-crown-6 (nb18c6) dibenzo-18-crown-6 (db18c6) and dicyclohexyl-18-crown-6 (dc18c6), dissolved in dichloromethane, are able to form oxonium-ion complexes in contact with aqueous sulfuric and hydrochloric acid solutions. this ability allows the transfer of cr(vi) oxanions from the acid media, through an orga...

2006
Maria Atanassova

The synergistic solvent extraction of 14 trivalent lanthanoids (except Pm) with 1-phenyl-3-methyl-4-benzoyl-5pyrazolone(HP) and dibenzo-18-crown-6 (DB18C6) or dibenzo-24-crown-8(DB24C8) in 1, 2-dichloroethane has been studied. It was found that in the presence of HP alone the lanthanoids have been extracted as LnP3∙HP and in the presence of mixtures of HP and crown ethers (S) − as LnP3∙S. On th...

The complexation reactions between Tl+ and Pb2+ ions and crown ethers 12-crown-4(12C4), 15-crown-5 (15C5), benzo-15-crown-5 (B15C5), 18-crown-6 (18C6), dicyclohexyl-18-crown-6 (DC18C6) and aza-18-crown-6 (A18C6) were studied in 90% acetonitrile and 90% ethanol solutions at 25 °C, using an a.c. polarographic technique. The stoichiometry and stability of the complexes we...

2014
Cheng-Chung Lee Manuel Maestre-Reyna Kai-Cheng Hsu Hao-Ching Wang Chia-I Liu Wen-Yih Jeng Li-Ling Lin Richard Wood Chia-Cheng Chou Jinn-Moon Yang Andrew H-J Wang

Crown ethers are small, cyclic polyethers that have found wide-spread use in phase-transfer catalysis and, to a certain degree, in protein chemistry. Crown ethers readily bind metallic and organic cations, including positively charged amino acid side chains. We elucidated the crystal structures of several protein-crown ether co-crystals grown in the presence of 18-crown-6. We then employed biop...

2017
Seyed Hossein Jamali Mahinder Ramdin Tim M Becker Shwet Kumar Rinwa Wim Buijs Thijs J H Vlugt

Crown-ethers have recently been used to assemble porous liquids (PLs), which are liquids with permanent porosity formed by mixing bulky solvent molecules (e.g., 15-crown-5 ether) with solvent-inaccessible organic cages. PLs and crown-ethers belong to a novel class of materials, which can potentially be used for gas separation and storage, but their performance for this purpose needs to be asses...

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