Sequence-dependent spontaneous symmetry breaking in precise liquid crystalline heterodimers

Spontaneous symmetry breaking in liquid crystals can arise from packing frustration induced by a bent molecular shape, which can be relieved through curvature across supramolecular length scales to form chiral structures. Structures with such spontaneous symmetry breaking can be harnessed for applications such as chiroptical displays or chiral templates. A unique class of structures formed by these systems is nanocylinders composed of heliconically scrolled smectic layers. Although nanocylinder formation from chiral mesogens can be controlled by parameters such as chiral center placement, the mechanisms of assembly and design criteria for achiral mesogens are not well established. Here we demonstrate two monodisperse, asymmetric, achiral mesogenic heterodimers of opposite sequence which form nanocylinders that assemble into drastically different supramolecular structures. One dimer self-assembles to exhibit a form of optical chirality known as dark conglomerate behavior. The other dimer forms a spiral arrangement of nanocylinders originating at spherulite centers but exhibits no optical chirality. These results demonstrate the crucial role of molecular design in hierarchical structure and chiral assembly of mesogenic systems.