Crystal Engineering and Functional Properties of Helical π-Conjugated Molecules

Chiral π-conjugated molecules have potential applications in spin-selective organic semiconductors and chiroptical electronic devices that are responsive to circularly polarized light. Their performance is expected to largely depend on how they assemble in the solid state, however, there are limited strategies for controlling the packing structure, particularly in helically-twisted π-conjugated molecules. In this work, a homochiral face-to-face columnar packing arrangement for helicene derivatives was achieved by modifying their helical ends with 2,1,3-thiadiazole structures. The observations provide useful insights into the chiral crystal engineering with helically twisted molecules and the development of chiral organic semiconductor materials.