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

The crystal structure of entinostat Form B, C₂₁H₂₀N₄O₃, has been solved and refined using laboratory X-ray powder diffraction data, and optimized using density functional techniques. Entinostat crystallizes in space group Pna2₁ and the crystal structure consists of inter-locking layers of entinostat mol-ecules parallel to the bc plane. A strong N-H⋯N hydrogen bond links the mol-ecules into zigzag chains propagating along the b-axis direction. The graph set for this pattern is C ¹ ₁(8). Two N-H⋯O hydrogen bonds link the mol-ecules along the c-axis direction. The graph sets for this pattern are C ¹ ₁(4) and C ¹ ₁(7).