Effects of Alkyl Substitution on the Multidentate Attachment of Alkali Metal Cations by Ligands in the Gas Phase: Kinetics and Thermochemistry of Cation Binding by Isomers of Dicyclohexano-18-crown-6

1995 ◽  
Vol 117 (31) ◽  
pp. 8197-8203 ◽  
Author(s):  
In-Hou Chu ◽  
David V. Dearden
Keyword(s):  
Alkali Metal ◽  
Gas Phase ◽  
Metal Cations ◽  
Cation Binding ◽  
Alkali Metal Cations ◽  
Gas Phase Kinetics ◽  
Alkyl Substitution

Tetrapyrrolic compounds as hosts for binding of halides and alkali metal cations

2009 ◽  
Vol 13 (11) ◽  
pp. 1148-1158 ◽  
Author(s):  
Mikalai M. Kruk ◽  
Aleksander S. Starukhin ◽  
Nugzar Zh. Mamardashvili ◽  
Galina M. Mamardashvili ◽  
Yulia B. Ivanova ◽  
...  
Keyword(s):  
Alkali Metal ◽  
Pyridine Ring ◽  
Alkali Metal Cation ◽  
Metal Cations ◽  
Cation Binding ◽  
Halide Ions ◽  
Alkali Metal Cations ◽  
Cation Complexation ◽  
Iodide Ions ◽  
Binding Isotherms

In this paper the binding of halides and alkali metal cations with porphyrin hosts is reported. The halide ions are complexed with diprotonated porphyrin macrocycle with high affinity and stable complexes of 1:1 and 1:2 structures with halide ions are formed. Strong (up to 300 times) quenching of the porphyrin fluorescence has been found upon the titration of porphyrin solutions with iodide ions. It was established that both static quenching upon formation of the non-fluorescent complex and dynamic diffusion-controlled quenching took place. It is shown that the halide ions binding isotherms can be linearized with double-logarithmic plots. The alkali metal cations are trapped with mono-meso-arylporphyrins containing a conformationally mobile complexing polyether fragment on the benzene ring with a terminal pyridine ring. The alkali metal cation binding constant depends on the polyether chain length. The five-membered (n = 5) polyether chain provides very high binding selectivity for potassium over lithium or sodium. The potassium complexation constants 3.6 × 105 and 7.2 × 104 M-1 have been obtained for Zn 2+ complex and diprotonated porphyrin, respectively. For signaling of the alkali cation complexation, it is proposed to use the binding between the terminal pyridine ring with either the Lewis acidic site (chelated Zn 2+ ion) or the diprotonated macrocycle core ( H 4 P 2+) acting as salt bridging site.

scholarly journals Discrimination between Alkali Metal Cations by Yeast

1967 ◽  
Vol 50 (4) ◽  
pp. 967-988 ◽  
Author(s):  
W. McD. Armstrong ◽  
A. Rothstein
Keyword(s):  
Alkali Metal ◽  
Competitive Inhibition ◽  
Metal Cations ◽  
Competitive Inhibitor ◽  
Cation Binding ◽  
Alkali Metal Cations ◽  
System A ◽  
Low Concentrations ◽  
K Transport ◽  
Noncompetitive Inhibitors

K+ is a competitive inhibitor of the uptake of the other alkali metal cations by yeast. Rb+ is a competitive inhibitor of K+ uptake, but Li+, Na+, and Cs+ act like H+. At relatively low concentrations they behave as apparent noncompetitive inhibitors of K+ transport, but the inhibition is incomplete. At higher concentrations they inhibit the remaining K+ transport competitively. Ca++ and Mg++ in relatively low concentrations partially inhibit K+ transport in an apparently noncompetitive manner although their affinity for the transport site is very low. In each case, in concentrations that produce "noncompetitive" inhibition, very little of the inhibiting cation is transported into the cell. Competitive inhibition is accompanied by appreciable uptake of the inhibiting cation. The apparently noncompetitive effect of other cations is reversed by K+ concentrations much higher than those necessary to essentially "saturate" the transport system. A model is proposed which can account for the inhibition kinetics. This model is based on two cation-binding sites for which cations compete, a carrier or transporting site, and a second nontransporting (modifier) site with a different array of affinities for cations. The association of certain cations with the modifier site leads to a reduction in the turnover of the carrier, the degree of reduction depending on the cation bound to the modifier site and on the cation being transported.

Neutral glycoconjugated amide-based calix[4]arenes: complexation of alkali metal cations in water

2018 ◽  
Vol 16 (6) ◽  
pp. 904-912 ◽  
Author(s):  
Nikola Cindro ◽  
Josip Požar ◽  
Dajana Barišić ◽  
Nikola Bregović ◽  
Katarina Pičuljan ◽  
...  
Keyword(s):  
Alkali Metal ◽  
Aqueous Solutions ◽  
Binding Sites ◽  
Metal Cations ◽  
Cation Binding ◽  
Water Soluble ◽  
Alkali Metal Cations ◽  
Complexation Reactions

Novel water-soluble calix[4]arene glycoconjugates with efficient cation-binding sites were synthesized and their complexation reactions in methanol and aqueous solutions were studied.

Oxidation of Peptide−Copper Complexes by Alkali Metal Cations in the Gas Phase

1996 ◽  
Vol 118 (22) ◽  
pp. 5314-5315 ◽  
Author(s):  
Tomáš Vaisar ◽  
Christine L. Gatlin ◽  
František Tureček
Keyword(s):  
Alkali Metal ◽  
Gas Phase ◽  
Copper Complexes ◽  
Metal Cations ◽  
Alkali Metal Cations
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