Tuning bilayer twist using chiral counterions

Cationic gemini surfactants with chiral counterions such as L-tartrate form gels by developing extended networks of multilamellar twisted ribbons. The chirality comes from the counterion, rather than from the amphiphile. Similar structures are found for diacetylenic lipids, glutamates and bile. The helical ribbons are unstable, evolving into tubules. Twisted ribbons have a curvature that differs from cylindrical curvature of helical ribbons, and no evolution towards closed chiral aggregates was observed. The twisted ribbons may be stable and the chirality can be continuously varied.