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Temperature-dependent structural properties, phase transition behaviour and dynamic properties of a benzene derivative in the solid state

DOI: 10.1021/acs.cgd.8b01775 DOI Help

Authors: Yating Zhou (Cardiff University) , Rhian Patterson (Cardiff University) , P. Andrew Williams (Cardiff University) , Benson M. Kariuki (Cardiff University) , Colan E. Hughes (Cardiff University) , Ranita Samanta (Indian Institute of Science Education and Research Kolkata) , Ramesh Devarapalli (Indian Institute of Science Education and Research Kolkata) , C. Malla Reddy (Indian Institute of Science Education and Research Kolkata) , David C. Apperley (University of Durham) , Kenneth D. M. Harris (Cardiff University)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Crystal Growth & Design

State: Published (Approved)
Published: March 2019

Abstract: We report the solid-state structural properties and phase transition behaviour of 1,4-dibromo-2,3,5,6-tetramethylbenzene, demonstrating that this material undergoes an order-disorder phase transition below ambient temperature (at ca. 156 K on cooling and ca. 159 K on heating). In both the high-temperature and low-temperature phases, the crystal structure is based on π-stacking of the molecules. In the high-temperature phase, the bromine and methyl groups are located with essentially equal probability in each of the six substituent positions, and it is shown by natural-abundance solid-state 2H NMR spectroscopy that, at ambient temperature, this disorder is dynamic via rapid molecular reorientation about an axis perpendicular to the aromatic ring. In the low-temperature phase, the bromine and methyl substituents occupy preferred sites within the crystal structure, with the distribution of site occupancies becoming progressively more ordered on decreasing temperature.

Subject Areas: Chemistry

Technical Areas: