X‑Ray Crystallography and its Role in Understanding the Physicochemical Properties of Pharmaceutical Cocrystals

Abstract

Properties of a matter are intrinsically dependent on the internal
arrangement of molecules in the solid state. Therefore, knowledge
of three-dimensional structure of the matter is a prerequisite for structure–
property correlations and design of functional materials. Over the
past century, X-ray crystallography has evolved as a method of choice
for accurate determination of molecular structure at atomic resolution.
The structural information obtained from crystallographic analysis paved
the way for rapid development in electronic devices, mineralogy, geosciences,
materials science, pharmaceuticals, etc. Knowledge of the
structural information of active pharmaceutical ingredients (APIs) is
a prerequisite for rational drug design and synthesis of new chemical
entities for development as new medicines. Over the past two decades,
X-ray crystallography has played a key role in the design of pharmaceutical
cocrystals—crystalline solids containing an API and one or more of
pharmaceutically acceptable coformers. These materials have proved
promising for fine-tuning several important properties of APIs. This short
review highlights the history of crystallography, early breakthroughs, and
the role of crystallography in understanding the physicochemical properties
of pharmaceutical cocrystals.