Orientational disorder of monomethyl-quinacridone investigated by Rietveld refinement, structure refinement to the pair distribution function and lattice-energy minimizations.

The crystal structure of the organic pigment 2-monomethyl-quinacridone (Pigment Red 192, CHNO) was solved from X-ray powder diffraction data. The resulting average structure is described in space group P\overline 1, Z = 1 with the molecule on the inversion centre. The molecules are arranged in chains.

Structure determination from powder data without prior indexing, using a similarity measure based on cross-correlation functions.

A method to refine organic crystal structures from powder diffraction data with incorrect lattice parameters has been developed. The method is based on the similarity measure developed by de Gelder et al. [J.

A two-dimensional polymer from the anthracene dimer and triptycene motifs.

A two-dimensional polymer (2DP) based on the dimerization of anthraceno groups arranged in a triptycene motif is reported. A photoinduced polymerization is performed in the crystalline state and gives a lamellar 2DP via a crystal-to-crystal (but not single-crystal to single-crystal) transformation. Solvent-induced exfoliation provides monolayer sheets of the 2DP.

Predicted and experimental crystal structures of ethyl-tert-butyl ether.

Possible crystal structures of ethyl-tert-butyl ether (ETBE) were predicted by global lattice-energy minimizations using the force-field approach. 33 structures were found within an energy range of 2 kJmol(-1) above the global minimum. Low-temperature crystallization experiments were carried out at 80-160 K.