Solvent-Regulated Self-Assembly of an Achiral Donor-Acceptor Complex in Confined Chiral Nanotubes: Chirality Transfer, Inversion and Amplification.

A chiral gelator was designed and found to form chiral nanotwists and nanotubes in toluene and DMSO, respectively, which could serve as host chiral matrices for fabricating functional soft materials. Achiral, π-conjugated donor and acceptor guests were doped into the gel, and solvent-regulated self-assembly was observed. Although both the DMSO and toluene gels containing three components look similar as transparent gels, it was clarified microscopically that, whereas achiral dopants self-assemble in the confined nanotubes in the DMSO gel, they only dissolve in the liquid phase in the toluene gel. The existence of the achiral donor and acceptor in different phases made their properties completely different. Chirality transfer occurred from the host chiral gel matrixes to guest achiral porphyrin in DMSO. Remarkably, the addition of C60 to the porphyrin/gelator gel could invert and further amplify the induced chirality of the porphyrin due to the formation of donor-acceptor pairs. On the other hand, no chirality transfer was observed in the toluene gel. These observations clearly unveiled the selective self-assembly of different components in distinct gel phases, which could provide new insight into the design of chiroptical soft materials.