Creation of chiral thixotropic gels through a crown-ammonium interaction and their application to a memory-erasing recycle system

A unique class of oligothiophene-based organogelator bearing two crown ethers at both ends was synthesized. This compound could gelatinize several organic solvents, forming one-dimensional fibrous aggregates. From the observation of circular dichroism, it was confirmed that the helical handedness of the fibrous assembly is controllable by the chirality of 1,2bisammonium guests, thus suggesting that one guest molecule bridges two gelator molecules through the crown-ammonium interaction. Interestingly, we have found that such chirality is created by thermal gelation, whereas it disappears by thixotropic gelation. The new finding implies that the present organogel system is applicable as a reversible switching memory device, featuring memory creation by a heat mode and memory erasing by a mechanical mode. Chiral memory switching: A unique class of functional organogelator based on crown ether appended oligothiophene was created, the chirality of which was influenced by the interaction with chiral ammonium guests. Stimuli-induced circular dichroism with controlled handedness of aggregates was observed. The reversibility of thixotropic/thermal behaviors can be applied to chirality switching memory devices (see scheme).