In addition, the influence of Coulomb's law on ion pairing interactions emphasises the role of distance and the dielectric constant in determining the strength of these interactions. Coulomb's law (Eq. 1) describes the attractive potential energy between two ions (q 1 and q 2 ). The magnitude of the electrostatic interaction is inversely related to the distance between the ions (r) and the dielectric constant of the medium (ε 0 ). Thus, strong ion-pairing interactions are preferred at short distances and in nonpolar solvents.