Orthogonal solvent "acity" (anion solvation) and "basity" (cation solvation) properties according to Swain et al..
C. G. Swain, M. S. Swain, A. L. Powell and S. Alunni;
J. Am. Chem. Soc. 105 (1983) 502-513.
Acity is measure of hydrogen bond acidity and is correlated with
→Dimroth-Reichardt ET (→ET vs Acity) and
→Gutmann AN (→AN vs Acity).
Basity is somewhat correlated with →Catalán SPP (→SPP vs Basity)