Organic Nanotube Bridge Fabrication by Controlling Molecular Self-Assembly Processes between Spherical and Tubular Formations

We examined a novel approach for nanometer-scale fabrication by controlling self-assembly of organic molecules. Organic amphiphile molecules typically self-assemble into a spherical or tubular structure, which depends on environmental conditions such as temperature, pH, and solvents. Here we demonstrate that self-assembly mechanisms of benzoic diacid diamide molecules can be switched between the spherical growth and the tubular growth by tuning pH to fabricate the combined structures. The benzoic diacid diamide molecules were first assembled into microspheres in a pH 8 solution. Once the microspheres were grown in diameter of 1 μm within 48 h, the self-assembly condition of benzoic diacid diamide was switched to the nanotube formation by tuning pH to 7. After 12 h, the nanotubes (50 nm in diameter) were observed between the microspheres.