We report a systematic solid state Na-23 nuclear magnetic resonance study of sodium complexes with crown ethers. cryptands, and naturally occurring antibiotic ionophores. Precise information about Na-23 quadrupole coupling constants and chemical shifts was determined from analysis of Na-23 magic-angle spinning (MAS) NMR spectra. We found that the experimental Na-23 chemical shifts can be related to an empirical parameter that is a function of the atomic valence of the donor ligand, the Na+-ligand distance, and the coordination number (CN) around the Nai ion of interest. A reasonably good correlation was also observed between the Na-23 quadrupole parameters measured in CDCl3 solution and those measured in the solid state, indicating that the cation exchange is slow in CDCl3. In MeOH solution, however, neither Na-23 quadrupole parameters nor chemical shifts of the Na-ionophore complexes show correlation with the corresponding solid-state data. Finally, eve report the Na-23 chemical shift tensor in Na(12C4)(2)ClO4: sigma (11) = sigma (22) = -1 ppm and delta (33) = -15 ppm.