Effect of paramagnetic metal ions on ¹H diffusion in trihexyltetradecylphosphonium benzoate ionic liquid

We have studied the effect of paramagnetic metal ion (neodymium) on the translational motion (diffusion) of Trihexyltetradecylphosphonium benzoate ionic liquid using pulsed field gradient NMR. 1D proton NMR results show that the cation and anion are both affected by the presence of neodymium ion. The paramagnetic lanthanide ion induces a downfield shift in the 1D NMR spectra. The 1H diffusion coefficients of the anion and cation are different and increase with temperature at low concentrations of neodymium. At higher neodymium concentrations, on the other hand the diffusion coefficients for of the cations and anions show the same value, which suggests the formation of aggregates around neodymium.