Crystal structure of β-d,l-psicose

Area of Science:

• Carbohydrate Chemistry
• Crystallography
• Structural Biology

Background:

• Psicose (allulose) is a C-3 epimer of fructose, a rare sugar with potential health benefits.
• Understanding the crystalline structure of sugars is crucial for their isolation, purification, and application.

Purpose of the Study:

• To determine the crystal structure of d-psicose and racemic d,l-psicose.
• To investigate the hydrogen bonding network and conformational properties of β-pyranose forms.

Main Methods:

• Crystallization of d-psicose and racemic d,l-psicose from aqueous solutions.
• X-ray diffraction analysis to determine the crystal structure and cell parameters.

Main Results:

• D-psicose and l-psicose form β-pyranose structures with specific conformations ((2)C5 and (5)C2, respectively).
• A distinct hydrogen bonding pattern was observed, involving intermolecular O-H⋯O bonds forming columns and a 3D network, along with an intramolecular bond.
• The cell volume of racemic β-d,l-psicose was found to be similar to that of chiral β-d-psicose.

Conclusions:

• The study elucidates the detailed crystal structure and hydrogen bonding of d-psicose and its racemic mixture.
• The findings provide insights into the solid-state behavior of psicose, relevant for its handling and potential applications.