Saddles as rotational locks within shape-assisted self-assembled nanosheets

Two-dimensional (2D) materials are a key target for many applications in themodern day. Self-assembly is one approach that can bring us closer to thisgoal, which usually relies upon strong, directional interactions instead ofcovalent bonds. Control over less directional forces is more challenging andusually does not result in as well-defined materials. Explicitly incorporatingtopography into the design as a guiding effect to enhance the interactingforces can help to form highly ordered structures. Herein, we show the processof shape-assisted self-assembly to be consistent across a range of derivativesthat highlights the restriction of rotational motion and is verified using adiverse combination of solid state analyses. A molecular curvature governedangle distribution nurtures monomers into loose columns that then arrange toform 2D structures with long-range order observed in both crystalline and softmaterials. These features strengthen the idea that shape becomes an impor-tant design principle leading towards precise molecular self-assembly and theinception of new materials.