Correlation of Nuclear Spin Resonance Line Widths with Formation Constants of Weak Complexes

Sodium-23 quadrupole coupling constants in different coordination shells from sodium-23 and carbon-13 Fourier transform nuclear magnetic resonance measurements on sodium cryptates

“…Ionic solvation has been investigated by many research groups using most of the available electrochemical and spectroscopic methods, including nuclear magnetic resonance spectroscopy.1 11Among metal cations, much work has been done on the sodium cation by direct observation on the 23Na nmr chemical shifts and quadrupolar broadening effects. [2][3][4][5][6][7][8][9][10][11][12][13] Knowledge of 23Na quadrupolar coupling constants, XNa = (e2qQ/h) (eQ = 23Na nuclear quadrupole moment), and electric field gradients, eq in various coordination states, would be of much interest to the understanding of the nature of cation solvation, but such determinations are hampered by the uncertainties in solvation number14 and the fluctuation of the coordination sphere.…”

“…Finally, when excess NaCl is added to the cryptate solutions two separate 23Na signals (free and complexed Na+) are observed, showing that cation exchange is slow at 35°. In the case of [3,Na+] coalescence occurs at about +58°giving a free energy of activation…”

Nuclear Magnetic Resonance Studies of Ions in Pure and Mixed Solvents

“…Space will not permit a discussion of these various methods. However, the potentiometric (300) and potentiometric pH; measurements might be mentioned since they permit• the determination of the formation constants of weak• complexes more accurately than nmr procedurespermit (104, 286). Thus formation constants for the• malate complexes of the alkali metals and of Ca+2,-Sr+2, and Ba+2 were determined with good accuracy using potentiometric pH measurements (104), whereas• nmr had given only approximate results (103).…”

Influence of Amino Acids, Ammonium and Potassium Cations on the Self‐Assembly of 5′‐GMP

“…-The effect of glycine could be due to removal by Gly of Na+ ions from their phosphate binding sites. Such displacement does not reflect competition of the Na+ ions between binding to the 5'-GMP phosphates or to the amino acid; in terms of binding constants, the former is approximately ten-fold greater than the latter [23] [24]. Decrease of p B .…”