Characterisation of the supramolecular structure of malonamides by application of pulsed field gradients in NMR spectroscopy

Abstract

Malonamides are known and extensively studied for their lanthanide and actinide extracting properties. Those studies have also highlighted aggregated phenomena and a splitting of the organic phase, in some particular experimental conditions. To explain this behaviour of extractants, ¹H NMR was used to study micellar phenomena by the determination of the self-diffusion coefficients of two malonamides only different by the length of their alkyl chain (DMDBTDMA and DMDBPMA), in presence of n-dodecane and for systems saturated with water or anhydrous. Several information on the aggregates and on the malonamide supramolecular structure were obtained by fitting the curves of self-diffusion coefficient vs. concentration and by conjugated NMR experimental data to potentiometric titrations and physical measurements.