Wirt-Gast-Komplexe von [bfu.bfu.bfu]: Vorhersage von Ionenselektivitäten mittels quantenchemischer Rechnungen XIII

2020 ◽  
Vol 75 (8) ◽  
pp. 769-775
Author(s):  
Ursula Palmer ◽  
Ralph Puchta
Keyword(s):  
Dft Calculations ◽  
Alkaline Earth ◽  
Ion Selectivity ◽  
Dihedral Angles ◽  
Alkali Cations ◽  
Dft Methods ◽  
Alkaline Earth Cation ◽  
Earth Cation ◽  
Model Equations

AbstractThe CH2–O–C2H4–O–CH2 moieties in Lehn’s cryptand [2.2.2] have been substituted by 2,2′-bifurane groups to get the cryptand [bfu.bfu.bfu]. The ion selectivity of this new cryptand was investigated by DFT calculations (RB3LYP/LANL2DZp, RB3LYP/LACVP*, RBP86/LANL2DZp and RBP86/LACVP*) based on model equations and analysis of the [M ⊂ bfu.bfu.bfu]n+ cryptate structures. The cryptand [bfu.bfu.bfu] is best suited for the alkali cations Na+ and K+, and the alkaline earth cation Sr2+ followed by Ca2+. The cavity of [bfu.bfu.bfu] is thus similar to that in [phen.phen.phen] or [bpy.bpy.bpy]. The selectivity of [bfu.bfu.bfu] is due to the flexibility of the OCCO und CN···NC dihedral angles. The results are independent of the selected DFT methods.

scholarly journals Dendrite-free alkali-metal electrodeposition from contact-ion-pair state induced by mixing alkaline earth cation

2021 ◽  
Author(s):  
Hongyi Li ◽  
Masaki Murayama ◽  
Tetsu Ichitsubo
Keyword(s):  
Alkali Metal ◽  
Alkali Metals ◽  
Alkaline Earth ◽  
Ion Pairs ◽  
Free Alkali ◽  
Alkali Cations ◽  
Metal Anode ◽  
Alkaline Earth Cation ◽  
Metal Electrodeposition ◽  
Earth Cation

Alkali metals, such as lithium and sodium, have been expected to be used for rechargeable metal-anode batteries owing to their low electrode potentials and large capacities. However, the well-known fatal problem, “dendritic growth” causing a dangerous short circuit, is faced while charging the batteries. Here, through a comprehensive study with electrochemical experiments, Raman and soft X-ray emission spectroscopies, density-functional-theory calculation, and molecular dynamic simulations, we provide an advanced guideline for electrolyte design in which a mixture of alkaline earth (Mg, Ca, Ba) salts is used to inhibit dendrite growth of alkali metals (Li, Na) during electrodeposition. Especially, focusing on CaTFSA2, as a salient exemplary alkaline-earth-cation additive, we demonstrate that dendrite-free morphology upon alkali-metal electrodeposition can successfully be attained by modifying their solvation structures in the dual-cation electrolyte systems. Adding divalent Ca2+ promotes alkali cation (Li+ or Na+) to form the contact ion pairs (CIPs) with the counter anions, which replaces the solvent-separated ion pairs (SSIPs) commonly existing in single-cation electrolytes. Such CIPs related to alkali cations would separate Ca2+ ions distantly to shield the strong coulomb interaction among the divalent cations. The stronger binding of the CIPs would retard the desolvation kinetics of alkali cations and, consequently, realizes a severely constrained alkali-metal electrodeposition in a reaction-limited process that is required for the dendrite-free morphology. This work provides prospects to construct dual-cation electrolytes for dendrite-free alkali-metal-anode batteries utilizing the concerted interactions between monovalent and multivalent cations.

Novel Na-3-Mica: Alkaline Earth Cation Exchange and Immobilization

2003 ◽  
Vol 38 (3) ◽  
pp. 679-694 ◽  
Author(s):  
Tatsuya Kodama ◽  
Kumi Hasegawa ◽  
Ken-ichi Shimizu ◽  
Sridhar Komarneni
Keyword(s):  
Cation Exchange ◽  
Alkaline Earth ◽  
Alkaline Earth Cation ◽  
Earth Cation

Alkaline earth cation binding to large and small bilayer phosphatidylserine vesicles

1982 ◽  
Vol 691 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Selwyn J. Rehfeld ◽  
Lee D. Hansen ◽  
Edwin A. Lewis ◽  
Delbert J. Eatough
Keyword(s):  
Alkaline Earth ◽  
Cation Binding ◽  
Alkaline Earth Cation ◽  
Earth Cation
Sign in / Sign up

Export Citation Format

Share Document