77HIGHLIGHTS 2020

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)

[1] C. Tschierske, Angew. Chem. Int. Ed. 52, 8828-8878 (2013). [2] C. Dressel et al., Angew. Chem. Int. Ed. 53, 13115-13120 (2014). [3] C. Tschierske & G. Ungar, ChemPhysChem 17, 9-26 (2016). [4] X. B. Zeng & G. Ungar, J. Mater. Chem. C 8, 5389-5398 (2020). [5] T. Reppe et al., Chem. Commun. 56, 711-714 (2020).

PRINCIPAL PUBLICATION AND AUTHORS

REFERENCES

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 [2]. 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 [4]. Note the matching helical sense of the

three confluent ribbons at network junctions in (d) and (g).