The saturation of negative charges of zeolites by specific cations to modify their physicochemical and catalytic properties has broadened the applications of zeolites. The adsorption behavior of H+ to Li+, Na+, K+, Rb+ and Cs+-saturated Linde-type A, Na-P1, mordenite, X type and Y type zeolites was evaluated at different pH-pM, where pH-pM is equal to log {(M+)/(H+)} and M+ represents either Li...

The formation and stability of alkali metal complexes with crown ethers containing an anthraquinone unit has been investigated in methanol and acetonitrile solutions by potentiometric methods. Complexes of 1:1 stoichiometry were observed for all the studied systems; 2:1 complexes were only detected for the larger alkali cations (Rb and Cs) and with the ligand with the larger macrocyclic cavity ...

This work demonstrates by means of DFT and ab initio calculations that recognition of alkali cations can be achieved by probing the variations of the second-order nonlinear optical properties along the commutation process in spiropyran/merocyanine systems. Due to the ability of the merocyanine isomer to complex metal cations, the switching between the two forms is accompanied by large contrasts...

The new ternary one-dimensional chain compounds K2ZrS4 , Rb2ZrS4 and Rb2HfS4 were prepared at 350 °C by reacting A2S3 and S with elemental M (A = K, Rb; M = Zr, Hf). They are isostructural, crystallizing in the orthorhombic space group Pbca with Z = 8 . The M atoms are in a distorted octahedral environment of four S2_ anions and one S22~ unit. The structure consists of infinite anionic chains c...

Intercalation of alkali metal cations, like Li+ or Na+, follows the same three-stage mechanism of the interfacial charge and mass transfer irrespective of the nature of the electrolyte, electrolyte composition or electrode material.

The binding affinity and selectivity of a new ionophore, [1(8)]starand (1), toward alkali metal cations in methanol were examined through NMR titration experiments and free energy perturbation (FEP) and molecular dynamics simulations. The preference was determined to be K(+) > Rb(+) > Cs(+) > Na(+) >> Li(+) in both FEP simulations and NMR experiments. The FEP simulation results were able to pre...

The binding of alkali and alkaline earth metal cations by macrocyclic and diazamacrobicyclic polyethers, composed of ordered arrays of hard oxygen (and nitrogen) donor atoms, underpinned the development of host-guest supramolecular chemistry in the 1970s and 1980s. The arrangement of -OCCO- and -OCCN- chelating units in these preorganized receptors, including, but not limited to, crown ethers a...

The alkali-metal ions, Li+, Na+ and K+, exhibit complex pH-dependent effects on sucrase that seem to involve at least three separate types of mechanism and, perhaps, an equal number of specific metal-binding sites. In metal-free buffers, the alkali metals give mixed activating effects below pH 7 that involve: 1) Affinitytype (K-type) activation kinetics, where the apparent K,,, decreases as the...

The complexation of alkali-metal cations with calix[4]arene tertiary amide derivative (L) was studied in N-methylformamide (NMF), N,N-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO) by means of microcalorimetric and UV spectrophotometric titrations. The Gibbs energies, enthalpies, and entropies for transfer of reactants and products from N-methylformamide to other solvents were determine...