Electrochemical determination of the stability of complexes formed by proton-ionizable ligands of 3,5-disubstituted 1H-pyrazole with phenethylamine.
The application of two extreme models for diffusion in two-component systems to electrochemically determine equilibrium constants is discussed. The application of cyclic voltammetric, diferential pulse and rotating-disc electrode voltammetric data to elucidate the stoichiometry and formation constant of complex species by applying a generalization of the molar-ratio method is described. Molar-ratio experiments permit the distinction between the limiting diffusive regimes. The values of the equilibrium stability constants for complexation of phenethylamine and phenethylammonium ions by a 26-membered dioxotetraester crown of 3,5-disubstituted 1H-pyrazole as free ligand 1[L] and as dipyrazolate anion 1'[L(2-)]2Na(+), respectively, were determined.
Diffusion coefficients and complex equilibria in solution-III Graphical evaluation of formation constants from diffusion coefficients.
The values of the individual diffusion coefficients of the complexes participating in a metal-ligand system of equilibria may be estimated when provisional values of the formation constants have been calculated from diffusion currents. In this paper a new graphical method, involving average diffusion coefficients observed for metal-ligand systems, is described. The method is applied to four such systems, chosen for the particular characteristics shown by them.
Lariat ethers. Synthesis and cation binding of macrocyclic polyethers possessing axially disposed secondary donor groups
The synthesis and cation binding properties of a series of macrocyclic polyethers which possess ligating arms that enhance cation binding is presented.