نتایج جستجو برای: crown ethers
تعداد نتایج: 25024 فیلتر نتایج به سال:
A 1,2-bis(pyridinium)ethane type axle containing a terpyridine chelate group, when combined with 24-membered crown ethers, forms [2]pseudorotaxanes, the stability of which can be controlled by coordination of metal ions with different geometries.
Preparation of (di)benzocrown-substituted aryl-zinc or -boron reagents and their palladium-catalysed cross-coupling with functionalised aryl halides is described for convenient synthesis of novel crown ether systems.
A number of new chiral crown compounds and lariat ethers have been synthesized starting from phenyl-D-glucopyranoside, methyl-D-glucopyranoside and galactopyranoside, methyl-D-mannopyranoside and 1,2:5,6-di-O-isopropylidene-D-mannitol, but the main emphasis was laid on their application. Some of the sugar-based macrocycles showed significant asymmetric induction as phase transfer catalysts in l...
Novel 2-benzothiazole-, 4-pyridine-, and 2- and 4-quinoline-based styryl dyes containing an N-methylbenzoaza-15(18)-crown-5(6)-ether moiety were synthesized. A detailed electronic spectroscopy study revealed high performance of these compounds as optical molecular sensors for alkali and alkaline-earth metal cations. They were shown to considerably surpass analogous chromoionophores based on N-p...
Phosphine is conformationally stable because of the high inversion energy barrier of the phosphorus atom, which allows the phosphorus atom to become a chiral center. Thus, enantiopure P-stereogenic 12-, 15-, 18-, and 21-membered aliphatic phosphines "diphosphacrowns" were synthesized from secondary P-stereogenic bisphosphine as a chiral building block. Their complexation behaviors with alkali m...
• The discovery of the first crown ether is described. Forty-seven other aromatic and saturated polyethers were synthesized and their properties determined. Many form stable crystalline complexes with alkali and alkaline earth salts. Some saturated crown ethers solubilize potassium hydroxide and permanganate in aromatic hydrocarbons, EThe SC!5 indicates that this paper has been cited in over 1,...
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