Halogen and hydrogen bonding in povidone-iodine and related co-phases.

Povidone-iodine is a widely used antiseptic and on the World Health Organization’s List of Essential Medicines. We report the X-ray crystal structure of a two-monomer unit model compound showing that the structure of povidone-iodine comprises protonated pyrrolidone units linked by intermolecular hydrogen bonds along with triiodide anions. We also report an unusual example of a system exhibiting both a cocrystal and coamorphous form in a halogen bonded lactam model compound with diiodotetrafluorobenzene