Molecular Interactions in Pharmaceutical Compounds

Small organic molecules, especially in the
pharmaceutical sciences, tend to crystallise in a plethora
of different crystal forms, either as pure compounds or
with the inclusion of solvent molecules. Due to their
changed physico-chemical characteristics, such as
melting point, compressibility, solubility and thus
bioavailability, and physical and chemical stability,
different crystal forms can pose a problem to the
manufacture of medicines.[1] It is thus crucial to
understand the crystallisation behaviour and
manufacturability of these compounds in order to avoid
problems in the life-time of the medicine and costly
recalls comparable to ritonavir[2] or rotigotine.[3]
Bioactive molecules and pharmaceuticals typically have
multiple functional groups, enabling them to interact with
receptors and thus show pharmacological action. In the
solid-state, the interactions through these functional
groups are the driving forces of molecular recognition.
By applying X-ray and neutron diffraction methods as
well as thermoanalysis, vapour sorption and
spectroscopic analysis in combination with computational
techniques, we are probing the strong and weak
interactions within the crystal forms and during the
crystallisation in order to understand and predict their
characteristics.