A left-handed building block self-assembles into right- and left-handed helices

Abstract

Self-assembly, the process by which building blocks spontaneously form an ordered structure, has become a key concept in soft matter science. In self-assembly, the physical properties of the building blocks determine the structure of the assembly. For example, the pitch and handedness of a self-assembled helix depend on the interactions between its constituent particles. There are many nanoscale building blocks of a single handedness that self-assemble into both left- and right-handed structures, but there is currently no model system that explains this ambiguous relationship between building block chirality and assembly chirality. Here we report the discovery of a family of left-handed building blocks that self-assemble into helices whose handedness can be tuned by a single building block parameter. In simulations, pairs of Paramonov–Yaliraki ellipsoids rigidly bound in a biphenyl-like arrangement self-assemble into helices. Adjusting the dihedral angle between the ellipsoids without altering the building block handedness was sufficient to produce both right- and left-handed helices. This model system should provide design insights for supramolecular assemblies of nanoscale structures with adjustable internal dihedral angles.