Complementary helicity interchange of optically switchable supramolecular-enantiomeric helicenes with (-)-gel-sol-(+)-gel transition ternary logic.

A gallamide-containing pseudoenantiomeric helicene pair bearing a (10R,11R)-dimethoxymethyldibenzosuberane core can self-assemble by intermolecular amide H-bonding and π-π stacking into bundled helical fibers with helical tunnels of complementary helicity in CH2Cl2. The helicenes undergo excellent complementary photoswitchings of ternary logic at 280, 318, and 343 nm through (-)-gel-sol-(+)-gel interconversion.

Dielectrophoretic placement of quasi-zero-, one-, and two-dimensional nanomaterials into nanogap for electrical characterizations.

DEP is one of promising techniques for positioning nanomaterials into the desirable location for nanoelectronic applications. In contrast, the lithography technique is commonly used to make ultra-thin conducting wires and narrow gaps but, due to the limit of patterning resolution, it is not feasible to make electrical contacts on ultra-small nanomaterials for a bottom-up device fabrication. Thus, integrating the lithography and dielectrophoresis, a real bottom-up fabrication can be achieved.

Nano approach investigation of the conduction mechanism in polyaniline nanofibers.

A nanotechnological approach is applied to measurements of the electric field dependence of resistance under a high electric field while in low voltage. With this technique, the conduction mechanism on a mesoscopic scale is explored in a single, nonagglomerated nanofiber. Polyaniline nanofibers are prepared by vigorous mixing of aniline and oxidation agent ammonium persulfate in acid solution.

Modulation of photoswitching profiles by 10,11-dialkoxymethyl substituents in c(2)-symmetric dibenzosuberane-based helicenes.

A series of C(2)-symmetric, 10,11-disubstituted dibenzosuberane (DBS)-based helicenes 6 a-c with a common 7-bromo-α-tetralin-based bottom fragment were synthesized. Their absolute stereochemistry was determined to be 10R,11R,P after reductive desulfurization of the corresponding (10R,11R,1'S)-episulfides with complete stereospecificity. Photoisomerization of the diastereomerically pure (P)-6 c in hexane led to virtually exclusive formation of the opposite M-form diastereomer (P/M', <1:>99) at 290 nm.