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Orientational correlations in liquid acetone and dimethyl sulfoxide: a comparative study.
Sylvia E McLain1, Alan K Soper, Alenka Luzar
1ISIS Facility, Rutherford Appleton Laboratories, Chilton, Didcot, UK. s.mclain@rl.ac.uk
The Journal of Chemical Physics
|February 25, 2006
Summary
The liquid structures of acetone and dimethyl sulfoxide reveal specific molecular dipole alignments. Molecules exhibit antiparallel configurations at short distances, transitioning to head-to-tail dipolar ordering further away.
Area of Science:
- Physical Chemistry
- Molecular Dynamics
- Liquid State Physics
Background:
- Understanding liquid structure is crucial for predicting macroscopic properties.
- Molecular interactions and orientations dictate fluid behavior.
- Acetone and dimethyl sulfoxide are common polar organic solvents with distinct structures.
Purpose of the Study:
- To investigate the liquid-state structure of acetone and dimethyl sulfoxide.
- To determine the orientational correlations and dipole alignments of these molecules.
- To explore the influence of molecular symmetry on spatial orientation.
Main Methods:
- Neutron diffraction measurements were employed to gather structural data.
- Empirical Potential Structure Refinement (EPSR) modeling was used to analyze the data.
- Analysis of orientational correlations from the EPSR model.
Main Results:
- Dipole alignment analysis revealed antiparallel configurations at short distances.
- At longer distances, molecules showed a predominant head-to-tail dipolar ordering.
- Molecular symmetry significantly influenced the spatial distribution of orientations around a central molecule.
- Weak methyl hydrogen to oxygen intermolecular contacts were observed, likely not hydrogen bonds.
Conclusions:
- The study elucidates the complex orientational ordering in liquid acetone and dimethyl sulfoxide.
- Dipolar interactions play a key role in structuring these liquids.
- Molecular symmetry is a critical factor governing intermolecular arrangements.