Structure of entinostat Form B, C₂₁H₂₀N₄O₃, derived using laboratory powder diffraction data and density functional...

Area of Science:

• Crystallography
• Solid-state chemistry
• Molecular modeling

Background:

• Entinostat is a potential therapeutic agent.
• Understanding the solid-state structure is crucial for drug development and formulation.

Purpose of the Study:

• To determine the crystal structure of entinostat Form B.
• To elucidate the intermolecular interactions governing its crystal packing.

Main Methods:

• Laboratory X-ray powder diffraction (XRPD) for data collection.
• Structure solution and refinement.
• Density functional theory (DFT) for structural optimization.

Main Results:

• The crystal structure of entinostat Form B (C21H20N4O3) was solved and refined.
• Entinostat crystallizes in the Pna21 space group.
• The structure features interlocking layers with zigzag chains formed by N-H⋯N hydrogen bonds (graph set C11(8)).
• Additional N-H⋯O hydrogen bonds (graph sets C11(4) and C11(7)) link molecules along the c-axis.

Conclusions:

• The detailed crystal structure of entinostat Form B has been established.
• The identified hydrogen bonding patterns provide insights into the molecular assembly and stability of entinostat.
• This structural information is valuable for further pharmaceutical development.