| 概 要 |
The turn of the twenty-first century welcomed the triumphant arrival of nanoscience/nanotechnology. The advent of nanocarbons, such as fullerenes and carbon nanotubes, along with the development of state-of-the-art single molecule imaging methods for the analysis of their motion at the nanoscale, was essential to make the Feynman's "plenty-of-room-at-the-bottom" prediction insightful and realistic. The elemental machinery of nanotube molecules, observed at the single-molecule level, provided proof-of-principle images of carbonaceous machines in action, and the observation of ultralow friction at the interface indeed demonstrated the uniqueness of carbonaceous systems and, moreover, the feasibility of Feynman's "Let the bearings run dry" statement in the nanoscale world. The bright futuristic image of the carbonaceous machines was further decorated by imaginative and arresting cartoons of futurists, which popularized the molecular machines (eg. http://www.nanoengineer-1.com/).
There still lies a wide chasm, however, between the single-molecule level and the real macroscopic world, where the Avogadro's number, as well as the statistical ensemble behaviours of molecules, take control over everyday phenomena. It is therefore quite reasonable for chemists to see a yet long path for carbonaceous nanomachines to be realised in quantity, and it was probably the same reason why futurists with a physical background dream of an illusory "molecular assemblers".
Our study aims at the chemical synthesis of nanocarbon "molecules"
with discrete structures. Utilizing single-bond linking strategy, we succeeded in the rational synthesis, and the new molecular nanocarbons allowed us to explore the science and technology of these materials. For instance, one of the most resent examples demonstrates a concise and scalable access to carbonaceous nanomachinery of a minimal form and provides a statistical evidence for the rolling motion of nanoscale molecular bearings functioning under ensemble dynamics. The collective motion of an enormous numbers of bearing molecules at the mole level was observed spectroscopically with the synchronous rolling speed controlled by temperature. In addition to the bottom-up synthesis of finite nanotube molecules for bearing shells, the extraordinary stability of supramolecular assembly and the elaborate design of symmetry were the elemental factors for this successful demonstration.
The non-directional van der Waals force at the carbonaceous interface for the assembly also makes the present system stand out from other bottom-up supramolecular machines featuring weak directional intermolecular forces.
See author's web page for further information:
http://www.orgchem2.chem.tohoku.ac.jp/
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