The liquid structure of the solvents dimethylformamide (DMF) and dimethylacetamide (DMA)

Abstract

The liquid structure of the commonly used solvents dimethylformamide (DMF) and dimethylacetamide (DMA)were measured using state-of-the-art state neutron diffraction augmented with isotopic substitution (NDIS) and interpreted with empirical potential structure refinement (EPSR). Both solvents are found to develop rich local ordering with similar local packing densities, though with differences related to their three-dimensional molecular structure. While DMF’s dipole preferentially orientates anti-parallel to maximise hydrogen bonding, DMA favours parallel arrangement maximising non-directional dispersive forces. The highly-developed local orientational structure found in these solvents rationalises their ability to solvate a range of charged and neutral nanomaterials and highlights that the understanding of nanomaterial dispersions is a multi-body problem in which the geometry of the molecule, as well its dipole moment, must be incorporated.