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 1,2-bisammonium 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.     

Unexpected chiral induction from achiral cationic polythiophene aggregates and its application to the sugar pattern recognition

The aggregates of a cationic polythiophene (PT1) formed in poor solvent in the presence of sugars showed the distinct circular dichroism activity, the intensity being well correlated with the specific optical rotation [α] of sugars: therefore, the present system is useful as a novel sugar structure reading-out method.     

Crystal Engineering Approach To Design Colorimetric Indicator Array To Discriminate Positional Isomers of Aromatic Organic Molecules

Discriminating by color : A 2D colorimetric indicator array has been designed by a crystal engineering approach (N???H? O hydrogen bonding and charge‐transfer complexation) involving solid‐state co‐grinding for the visual discrimination of positional isomers of dihydroxynaphthalene. Factors governing the close packing of π planes, and hence color of the complex, were determined by single‐crystal X‐ray analysis, allowing fine tuning by crystal engineering.