Construction of an organic crystal structural model based on combined electron and powder X-ray diffraction data and the charge flipping algorithm

The structure of an organic dye 1,5-diaminoanthraquinone (DAAQ) nanowire was studied by both electron diffraction and X-ray powder diffraction. The unit cell of the crystal was determined from a series of tilted selected area electron diffraction patterns (monoclinic: a=3.78 Å, b=9.73 Å, c=15.01 Å and β=82.4°). By using precession electron diffraction, the following extinction conditions were determined, 0k0: k=2n and 00l: l=2n, which give the space group as P21/C (no. 14). The powder charge flipping algorithm was applied to resolve the phase problem and the structural model of the DAAQ crystal was built.