Shaping the cavity of calix[4]arene using transition metals and binding alkali-metal cations inside the cavity: the relevance of the alkali-metal cation–arene interaction

1997 ◽  
pp. 183-184 ◽  
Author(s):  
Antonio Zanotti-Gerosa ◽  
Euro Solari ◽  
Luca Giannini ◽  
Carlo Floriani ◽  
Angiola Chiesi-Villa ◽  
...  
Keyword(s):  
Transition Metals ◽  
Alkali Metal ◽  
Metal Cation ◽  
Alkali Metal Cation ◽  
Metal Cations ◽  
Alkali Metal Cations

scholarly journals The effect of the alkali metal cation on the electrocatalytic oxidation of formate on platinum

RSC Advances ◽  
2014 ◽  
Vol 4 (29) ◽  
pp. 15271-15275 ◽  
Author(s):  
Bruno A. F. Previdello ◽  
Eduardo G. Machado ◽  
Hamilton Varela
Keyword(s):  
Alkali Metal ◽  
Metal Cation ◽  
Electrocatalytic Oxidation ◽  
Alkali Metal Cation ◽  
Metal Cations ◽  
Alkali Metal Cations ◽  
Non Covalent Interactions ◽  
Electro Oxidation ◽  
Covalent Interactions

Non-covalent interactions between hydrated alkali metal cations and oxygenated species on platinum considerably impact the mechanism of formate electro-oxidation.

Crystal Structures of Titanium(III) Bis(acetylide) Tweezer Complexes with Alkali Metal Cations

1997 ◽  
Vol 62 (9) ◽  
pp. 1446-1456 ◽  
Author(s):  
Jörg Hiller ◽  
Vojtech Varga ◽  
Ulf Thewalt ◽  
Karel Mach
Keyword(s):  
Alkali Metal ◽  
Crystal Structures ◽  
Metal Cation ◽  
Alkali Metal Cation ◽  
Metal Cations ◽  
Polymer Chains ◽  
Alkali Metal Cations ◽  
Bonding Interaction ◽  
Intermolecular Bonding ◽  
Trimethylsilyl Groups

Crystal structures of the Ti(III) tweezer complexes [(C5HMe4)2Ti(σ-C≡CSiMe3)2]-[Li(THF)2]+ (2a), [(C5HMe4)2Ti(σ-C≡CSiMe3)2]-Na+ (3) and [(C5HMe4)2Ti(σ-C≡CSiMe3)2]-Cs+ (5) have been determined. In all of them the alkali metal cation is placed away from the Ti-Cα1-Cα2 plane at the distance: Li+ 0.511 Å, Na+ 1.023 Å and Cs+ 0.521 Å. The reason for the deviation of Li+ in 2a is the asymmetrical orientation of the THF ligands in the [Li(THF)2]+ cation with respect to the Ti-Cα1-Cα2 plane, which seems to release the steric congestion between the THF ligands and the trimethylsilyl groups. In 3 and 5, the molecules form polymer chains with a weak intermolecular bonding interaction between the cations and one of the C5HMe4 ligands of the neighbouring molecule in a sandwich manner.

Study of photocatalytic reaction of methanol with water over Rh-, and Pd-loaded TiO2 catalysts. The role of added alkali metal cations

1986 ◽  
Vol 64 (9) ◽  
pp. 1795-1799 ◽  
Author(s):  
Shuichi Naito
Keyword(s):  
Alkali Metal ◽  
Metal Cation ◽  
Methyl Formate ◽  
Alkali Metal Cation ◽  
Metal Cations ◽  
Photocatalytic Reaction ◽  
Product Selectivity ◽  
Alkali Metal Cations ◽  
Selectivity Change

The product selectivity of the photocatalytic reaction of methanol with water is changed drastically by the addition of alkali metal cations to Rh- and Pd-loaded TiO2 catalysts. Over alkali metal cation free catalysts, the main products are 1:1 ratio of H2 and dimethoxymethane, which is replaced with H2, methyl formate, and CO2 over alkali metal cation added catalysts. The role of added alkali metal cations is the stabilization of the reaction intermediate as adsorbed formate instead of adsorbed formaldehyde, which causes the selectivity change from dimethoxymethane to methyl formate.

scholarly journals Alkali Metal Cation Transport and Homeostasis in Yeasts

2010 ◽  
Vol 74 (1) ◽  
pp. 95-120 ◽  
Author(s):  
Joaquín Ariño ◽  
José Ramos ◽  
Hana Sychrová
Keyword(s):  
Plasma Membrane ◽  
Alkali Metal ◽  
Metal Cation ◽  
Higher Plants ◽  
Alkali Metal Cation ◽  
Metal Cations ◽  
Cation Transport ◽  
Transport Processes ◽  
Alkali Metal Cations ◽  
Yeast Saccharomyces Cerevisiae

SUMMARY The maintenance of appropriate intracellular concentrations of alkali metal cations, principally K+ and Na+, is of utmost importance for living cells, since they determine cell volume, intracellular pH, and potential across the plasma membrane, among other important cellular parameters. Yeasts have developed a number of strategies to adapt to large variations in the concentrations of these cations in the environment, basically by controlling transport processes. Plasma membrane high-affinity K+ transporters allow intracellular accumulation of this cation even when it is scarce in the environment. Exposure to high concentrations of Na+ can be tolerated due to the existence of an Na+, K+-ATPase and an Na+, K+/H+-antiporter, which contribute to the potassium balance as well. Cations can also be sequestered through various antiporters into intracellular organelles, such as the vacuole. Although some uncertainties still persist, the nature of the major structural components responsible for alkali metal cation fluxes across yeast membranes has been defined within the last 20 years. In contrast, the regulatory components and their interactions are, in many cases, still unclear. Conserved signaling pathways (e.g., calcineurin and HOG) are known to participate in the regulation of influx and efflux processes at the plasma membrane level, even though the molecular details are obscure. Similarly, very little is known about the regulation of organellar transport and homeostasis of alkali metal cations. The aim of this review is to provide a comprehensive and up-to-date vision of the mechanisms responsible for alkali metal cation transport and their regulation in the model yeast Saccharomyces cerevisiae and to establish, when possible, comparisons with other yeasts and higher plants.

N-Methylbenzoaza-18-crown-6-ether derivatives as efficient alkali metal cations sensors: the dipole moment and first hyperpolarizability

RSC Advances ◽  
2014 ◽  
Vol 4 (47) ◽  
pp. 24433-24438 ◽  
Author(s):  
Ying Gao ◽  
Shi-Ling Sun ◽  
Hong-Liang Xu ◽  
Liang Zhao ◽  
Zhong-Min Su
Keyword(s):  
Dipole Moment ◽  
Alkali Metal ◽  
Atomic Number ◽  
Metal Cation ◽  
Dipole Moments ◽  
Alkali Metal Cation ◽  
Metal Cations ◽  
First Hyperpolarizability ◽  
Alkali Metal Cations

1-Li+, 1-Na+ and 1-K+ complexes formed by N-methylbenzoaza-18-crown-6-ether derivatives with one alkali metal cation were investigated. Their dipole moments and first hyperpolarizabilities take on opposite trends with increasing the atomic number.

Interactions between metal cations and the ionophore lasalocid. Part 10.—Gibbs functions, enthalpies, entropies and volumes for proton–alkali-metal cation exchange in a water–chloroform system

1992 ◽  
Vol 88 (7) ◽  
pp. 1009-1015 ◽  
Author(s):  
Rachid Lyazghi ◽  
Marc Hebrant ◽  
Madeleine Tissier ◽  
Yvon Pointud ◽  
Jean Juillard
Keyword(s):  
Alkali Metal ◽  
Cation Exchange ◽  
Metal Cation ◽  
Alkali Metal Cation ◽  
Metal Cations

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.

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