Single Crystal X-Ray Structure Determination

Single crystal X-ray structure determination is the process of locating the atoms within the unit cell using patterns that are created by an X-Ray beam diffracting from the repeating arrangement of electron density (atoms) within a single crystal. Each crystal form will have a unique crystal structure.

Single crystal structure determination provides valuable information including:

• Clear proof of a single phase
• Coformer (water, solvent, counterion, etc.) stoichiometry
• Unambiguous absolute configuration for chiral molecules
• Molecular structure confirmation
• Molecular structure determination if unknown (impurities)
• Crystal density
• Unit cell parameters
• Calculated X-Ray powder diffraction patterns for comparison with experimental

It is recommended to obtain the crystal structure of all forms of interest if possible, with particular emphasis on anhydrous and hydrated forms.  The single crystal structure is also the best way to confirm (or determine if unknown) the molecular absolute configuration.

Improved Pharma has an in-house Rigaku XtaLAB Synergy-i diffractometer.  The instrument is equipped with a copper X-Ray source, four circle kappa goniometer, and a pixel array direct photon counting detector for high quality data from crystals on the order of 100 microns in size at temperatures from 100 K to ambient.

The crystal structure of sodium acetate trihydrate was obtained at Improved Pharma and the atomic displacement ellipsoid diagram is shown below.  Information about the structure can be seen in the table.