Nuclear Magnetic Resonance Studies of Some Cation- and Anion-Exchange Resins in Dimethyl Sulfoxide-Water Systems

Nuclear magnetic resonance (NMR) data were reported for AG 50W,H⁺ cation-exchange resin and AG1, Cl^- anion-exchange resin suspended in DMSO-water mixtures. An increase in concentration of DMSO from 1.06 M to 13.4 M produced an upfield shift for external water peaks from T 5.19 to T 6.12 and a downfield shift from T 3.62 to T 0.30 for internal water peaks in AG 50W. For AG1, Cl^- resin, an upfield shift was also observed with the increase in DMSO concentration. The behavior of chemical shifts in these resins was explained in terms of the strong interaction between DMSO and water molecules and the influence of aromatic nuclei in the resin. The longitudinal relaxation times went through minima in these resins at a mole fraction of water 0.6 ≈ 0.7, indicating the formation of DMSO‧2H₂O complex.