Soft Rectangular Sub-5 nm Tiling Patterns by Liquid Crystalline Self-Assembly of T-Shaped Bolapolyphiles

Square and other rectangular nanoscale tiling patterns are of contemporary interest for soft lithography. Though soft square patterns on a ≈40 nm length scale can be achieved with block copolymers, even smaller tiling patterns below 5 nm can be expected for liquid crystalline phases of small molecules. However, these usually form lamellar and hexagonal morphologies and thus the challenge is to specifically design liquid crystal (LC) phases forming square and rectangular structures, being compatible with industrial standards. Here, two distinct types of liquid crystalline rectangular tiling patterns are reported occurring in a series of T-shaped p-terphenyl-based bolapolyphiles. By directed side chain engineering sub-5 nm sized quadrangular honeycombs with rhombic (c2mm), square (p4mm), and rectangular (p2mm) shapes of the cells are formed by spontaneous self-assembly. The rectangular honeycomb with p2mm lattice represents a new mode of LC self-assembly in polygonal honeycombs. In addition, pentagonal and hexagonal tiling motifs can be obtained by molecular fine tuning.