- Synthesis and characterization of p-t-butyl calix[4]crown-4 and its double calix[4]arene dimer
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The preparation, separation, characterization and crystal structure determinations of the 1+1 and 2+2 condensation products, p-t-butyl calix[4]crown-4 (1) and its dimer double calix[4]arene double crown-4 (2), resulting from the reaction of p-t-butylcalix[4]arene with triethylene glycol ditosylate in the presence of a base are reported.
- Asfari, Zouhair,Thuery, Pierre,Nierlich, Martine,Vicens, Jacques
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- Molecular Design of Calixarene-Based Sodium-Selective Electrodes Which Show Remarkably High 105.0 - 105.3 Sodium/Potassium Selectivity
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Several ionophores for the Na+-selective electrode were developed from calixarene crown ethers with a short -(CH2CH2O)2CH2CH2- crown loop on the lower rim.The ionophoric cavities generated in these ionophores are much smaller and more rigid than those derived from calixarene crown ethers with a long -(CH2CH2O)3CH2CH2- crown loop.It was shown that two electrodes possess Na+ selectivity (with respect to K+) exceeding a factor of 105 which is higher by more than two orders of magnitude than that of the former calixarene-based Na+-selective electrodes!
- Yamamoto, Hiromasa,Shinkai, Seiji
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- Synthesis and evaluation of novel 1, 3-bridged calix[4]arene-crown ethers for selective interaction with Na+/K+ cations
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Calix[4]arenes possessing electron-donating groups (OH and OR) at the lower rim when reacted with tosylated polyethers under basic conditions give the corresponding 1, 3-disubstituted calix[4]arene-crown ethers 2a-2h, in good yields. The binding properties of the synthesized 1, 3-bridged calix[4]arene-crown ethers for alkali metal cations have been investigated by atomic emission spectrometric analysis. It has been observed that recognition of sodium and potassium varies with the size of the polyether chain as well as the substituents on the free phenolics of the calix[4]arene-crown ether. The potassium/ sodium selectivity seems to be governed primarily by the size of the crown ring, relative hydrophobicity and cation-pinteraction capability to give efficiency order as 2a, 2d>2 h>2c, 2e>2b, 2f>2 g.
- Chawla, Har Mohindra,Hundal, Geeta,Kumar,Singh, Parminder
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experimental part
p. 323 - 330
(2012/09/22)
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- Di-ionizable p-tert-butylcalix[4]arene-1,3-crown-4 ligands: synthesis and alkaline earth metal cation extraction
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A series of di-ionizable calix[4]arene-1,3-crown-4 compounds has been synthesized. The ionizable groups are oxyacetic acid and N-(X)sulfonyl oxyacetamide groups with X=methyl, phenyl, 4-nitrophenyl and trifluoromethyl, which 'tunes' the acidity of the latter. The efficiency and selectivity of these novel ligands are assessed with competitive solvent extractions of alkaline earth metal cations from aqueous solutions into chloroform. The results are compared with those reported previously for calix[4]arene-crown analogues with crown-6 and crown-5 rings.
- Liu, Xiaodong,Surowiec, Kazimierz,Bartsch, Richard A.
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scheme or table
p. 5893 - 5898
(2011/03/17)
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- Facile synthesis of cone p-tert-butylcalix[4]arene-crown conformers
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The series of p-tert-butylcalix[4]arene-crowns in the cone conformation was synthesised in high yields under conditions producing disubstituted calix[4]arenes in the presence of K2CO3 in acetonitrile; the formation of calix-bis(crown)s and doubly(calix)-doubly(crown) in these reactions was established.
- Alekseeva, Elena A.,Basok, Stepan S.,Mazepa, Alexander V.,Gren, Andrei I.
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p. 330 - 331
(2008/03/30)
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