Molecular Level Understanding of the Reversible Phase Transformation between Forms III and II of Dapsone.

ABSTRACT: The reversible solid-state phase transformation between the neat forms II and III of dapsone (DDS) was studied using thermal analytical methods, variable temperature X-ray diffraction and solid-state modeling at the electronic level. The first order III ↔ II phase transformation occurs at 78 ± 4 °C with a heat of transition of 2 kJ mol^-1 and a small hysteresis. The two isosymmetric polymorphs (both P2₁2₁2₁) differ only in movement of layers of molecules and show a small variation in conformation. The combination of variable-temperature single-crystal structure determinations and pair-wise intermolecular energy calculations allowed us to unravel the single-to-single crystal transformation at a molecular level, to

SUBMITTER: Braun DE 

PROVIDER: S-EPMC6191030 | biostudies-literature | 2017 Sep

REPOSITORIES: biostudies-literature