13C and 23Na n.m.r. studies of the interactions between cations and kryptofix (2,2) bound to soluble or gel polyacrylamide

Interactions between univalent cations (Li⁺, Na⁺, K⁺, Ag⁺) and bivalent cations (Ba²⁺, Ca²⁺) with kryptofix (2,2) substituted polyacrylamide have been investigated using ¹³C n.m.r. The tendency to form complexes involves the dimensions of both the hydrated ion and the cavity size macrocycle and for Ag⁺ the nature of the interaction site. The sensitivity of the ²³Na n.m.r. method for detecting complex formation in solution from macromolecular species has been applied to the determination of the conditional formation constants of Na⁺ and Ba²⁺ complexes.