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.

GRAPHICAL ABSTRACT

KEYWORDS:

• Liquid structure
• neutron scattering
• aprotic solvent
• dimethylacetamide
• dimethylformamide

Acknowledgements

We acknowledge the Science and Technology Facilities Council (STFC) for beam time at the ISIS Pulsed Neutron and Muon Source through allocations RB1610416 (doi:10.5286/ISIS.E.RB1610416) and RB1700030 (doi:10.5286/ISIS.E.RB1700030).

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

A. J. Clancyhttp://orcid.org/0000-0002-1791-8999

M. S. P. Shafferhttp://orcid.org/0000-0001-9384-9043

N. T. Skipperhttp://orcid.org/0000-0003-2940-3084

T. F. Headen http://orcid.org/0000-0003-0095-5731

C. A. Howard http://orcid.org/0000-0003-2550-0012

Additional information

Funding

We thank the Engineering and Physical Sciences Research Council for studentship funding via the CDT for the Advanced Characterization of Materials for N.S.B (grant number EP/L015277/1). P.L.C. thanks the EPSRC for support via his fellowship EP/S001298/1. A.J.C. would like to thank the Society of Chemical Industry and The Ramsay Memorial Fellowship Trust.