Helical Networks of π-Conjugated Rods A Robust Design Concept for Bicontinuous Cubic Liquid Crystalline Phases with Achiral Ia 3d and Chiral I23 Lattice, C. Dressel (a), T. Reppe (a), S. Poppe (a), M. Prehm (a), H. Lu (b), X. Zeng (b), G. Ungar (b,c) and
C. Tschierske (a), Adv. Funct. Mater. 30, 45, 2004353 (2020); https://doi.org/10.1002/ adfm.202004353. (a) Institute of Chemistry, Martin Luther University Halle-Wittenberg (Germany) (b) Department of Materials Science and
Engineering, University of Sheffield (UK) (c) Shaanxi International Research Center for Soft Materials, Xi an Jiaotong University (China)
 C. Tschierske, Angew. Chem. Int. Ed. 52, 8828-8878 (2013).  C. Dressel et al., Angew. Chem. Int. Ed. 53, 13115-13120 (2014).  C. Tschierske & G. Ungar, ChemPhysChem 17, 9-26 (2016).  X. B. Zeng & G. Ungar, J. Mater. Chem. C 8, 5389-5398 (2020).  T. Reppe et al., Chem. Commun. 56, 711-714 (2020).
PRINCIPAL PUBLICATION AND AUTHORS
or, if the growth is fast compared to seed formation, ending as a single homochiral domain permeating the entire material [2-4]. It is shown that by the design of the apex substitution, the mesophase type can be tailored, and a sequence of three different modes of cubic self-assembly is observed, following a growing apex size and the associated increasing helical twist. Accordingly, two ranges of the achiral double gyroid Ia 3d phase can be distinguished; a long pitch (Ia 3d(L)) and a short pitch (Ia 3d(S)), with the chiral triple network I23 Cubbi phase in the intermediate
pitch range [4,5]. These helical networks composed of π-conjugated rods might become of potential interest for aggregation-induced (circular polarised) emission in a wide range of technologies. The ultrasmall nanostructures with a sub-5 nm network distance also have potential use for lithographic templates.
Fig. 62: a) Molecular structure of the investigated molecules. b,e) electron
density maps reconstructed from diffraction intensities. c,f) Structural models showing the network structures of the investigated
Cubbi phases. d,g) As (c,f), shown in ribbon representation. b) Ia 3d cubic phase. In the
electron density map, the green isoelectron surface encloses predominantly the aromatic
rods, while the orange surface encloses the alkyl chains. c-d) The two enantiomorphous
network of the double gyroid represented in (d) as twisted ribbons . Each rib
represents a raft of three molecules. e) Electron density map of the I23 cubic
phase. f-g) The large unit cell with the three interpenetrating twisted networks . Note the matching helical sense of the
three confluent ribbons at network junctions in (d) and (g).