Helical Nanofilament Phases
In the formation of chiral crystals, the tendency for twist in the orientation of neighboring molecules is incompatible with ordering into a lattice: Twist is expelled from planar layers at the expense of local strain. In a recent report in Science (Helical Nanofilament Phases, L.E. Hough et al., Science 325 (2009) 456), a collaboration including scientists at Boulder (USA), the Technical University Berlin and Humboldt University Berlin reports the ordered state of a neat material in which a local chiral structure is expressed as twisted layers, a state made possible by spatial limitation of layering to a periodic array of nanoscale filaments. Although made of achiral molecules, the layers in these filaments are twisted and rigorously homochiral — a broken symmetry. The precise structural definition achieved in filament self- assembly enables collective organization into arrays in which an additional broken symmetry — the appearance of macroscopic coherence of the filament twist — produces a liquid crystal phase of helically precessing layers.
The work was initiated in preparation for the Sfb448 “Mesoscopically Organized Composites”, which started in 1998 and comes to an end this year (Final International Symposium on September 3 & 4, 2009, in Berlin- Adlershof).
Link to How Deformation Can Lend a Hand to Molecular Ordering
Link to Sfb448 Mesoscopically Organized Composites
Contact: Prof. Dr. Jürgen P. Rabe