Abstract
A simple N,N′-diaryl urea derivative was found to form four different anhydrous crystal forms (I−IV°), which can be crystallized in pure form by several techniques from solution as well as from the melt. These polymorphs were characterized by thermomicroscopy, differential scanning calorimetry, Fourier-transform infrared spectroscopy and single crystal and powder X-ray diffraction. The polymorphs were found to be purely monotropically related with large differences in their heats of fusion (11.1 kJ mol−1 for the least stable form I, 34.5 kJ mol−1 for the most stable form IV°). The crystal structures of all forms show the same conformer for forms I−III and a second conformer in form IV°. However, the hydrogen bonding motifs in all of the polymorphs are the same and thus the compound can be seen as a model for the importance of the entire crystal packing arrangement to the overall energy and stability of the crystal form, as opposed to just a few dominant interactions.
Original language | English |
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Pages (from-to) | 880-886 |
Number of pages | 7 |
Journal | Crystal Growth and Design |
Volume | 10 |
Issue number | 2 |
DOIs | |
Publication status | Published - 19 Nov 2009 |
Keywords
- crystal structure
- crystallization
- crystals
- melting
- modification