Investigation of an inclusion compound of trans-1,3-bis(3,4-dimethoxyphenyl)-2,3-epoxy-1-propanone with chloroform by NMR spectroscopy and X-ray crystallography

trans-1,3-Bis(3,4-dimethoxyphenyl)-2,3-epoxy-1-propanone crystallizes in a monoclinic form (m.p. 155-156 degrees C, from ethanol) and a trigonal form (m.p. 125-126 degrees C, from chloroform/hexane or chloroform). NMR studies revealed that chloroform is present in the crystals of the trigonal form ( epoxide/chloroform ratio approximate to 3:1). Solid-state NMR experiments s howed that the trigonal form was gradually converted into the monoclinic fo rm on storage in vacuo. On the basis of NMR and X-ray examinations it was c oncluded that the trigonal form is an inclusion compound of trans-1,3-bis(3 ,4-dimethoxyphenyl)-2,3-epoxy-1-propanone with chloroform. The crystal stru cture of the trigonal form with space group of R (3) over bar, a = 36.0354( 4), c = 8.2743(2) Angstrom, and Z = 18, has been refined to R = 0.0506 by t he employment of the SQUEEZE procedure implemented in PLATON-94.