Polymorphism,crystal structure and crystal habit of β-artemether

Polymorphism is a key crystal product property.The effects of crystallization method and operating condition on polymorphism of β-artemether were investigated.Single-crystal X-ray diffraction and X-ray powder diffraction(XRPD)were performed to identify the crystal structure of β-artemether,and molecular dynamics simulation coupled with the direct-space approach was used to simulate the crystal structure based on XRPD pattern of β-artemether polymorph.Two crystal structures were confirmed,one was a monoclinic crystal with space group of P21,the other was a triclinic crystal with space group of P-1.DSC analysis and XRPD patterns showed that the polymorphs of β-artemether were enantiotropic,and temperature was the key factor that affected polymorphic transformation.The crystal habit of polymorph A was predicted based on AE model and BFDH model,and the results showed that the theoretical crystal habit based on AE model coincided with the observed crystal habit.