First molecular quasicrystal is designed

The feasibility of constructing quasicrystals using organic molecules as building units has been demonstrated by chemists at Cardiff University, Wales (ChemPhysChem 2006, 7, 1649). Quasicrystals exhibit X-ray diffraction patterns that contain sharp diffraction maxima like those of crystals, but unlike crystals, they do not have periodic repeating structures. Previously reported examples of quasicrystals all have been metal alloy materials. Zhongfu Zhou and Kenneth D. M. Harris applied crystal engineering principles to design an energetically stable quasicrystalline structure from molecules of carboxylic acid derivatives of 10,5-coronene (example shown) that interact by hydrogen bonding. The team's calculations show that the structure, based on Penrose tiling−a nonperiodic pattern of two rhombus tiles−would give rise to a diffraction pattern with 10-fold symmetry, which is forbidden for crystals. The design strategy opens up new prospects in the study of quasicrystalline materials, according to Harris. The Cardiff group now plans to use the strategy to tackle the preparation of molecular quasicrystals and to explore their physical and chemical properties.