Diamondoids: Potential candidate for the Nanotech.

Anant Babu Marahatta
Tohoku University
Sendai, Japan

One of the current aspects of chemistry is being a watch-dog of the nanoworld which is a major discipline in Nanotechnology. In the context of building materials for nanotechnology components and in “bottom-up” approaches of chemistry, diamondoids have been of great interest in recent years.

Most generally, diamondoids refer to structures that resemble diamond consisting of a number of six-member carbon rings fused together. They are strong, stiff structures containing dense, 3-D networks of covalent bonds, formed chiefly from first and second row atoms with a valence of three or more. Various hetero-atoms which might include N, O, Si, S, and so forth, some time, act as the major substituent.

Here is the animation obtained by the Molecular Dynamics simulation of the diamondoids.



The carbon-carbon framework of them constitutes the fundamental repeating unit in the diamond lattice structure. More explicitly, they consist of repeating units of ten carbon atoms forming a tetra-cyclic cage system. Above figure illustrates the smaller diamondoid molecules, with the general chemical formula C(4n+6)H(4n+12): adamantane (C10H16), diamantane (C14H20), triamantane (C18H24) and so on. Graphite, Carbon nano tubes consisting of sheets of carbon atoms rolled into tubes, spherical buckyballs (Fullerene) are also included in the class of diamondoids materials.

They are ultra stable, saturated organic compounds (hydrocarbons) with unique structures and properties. The cage nature of them (polymantanes, adamantologues) is very promising architectures for modeling nano structures. This family of compounds (with over 20,000 variants) is one of the best candidates that offer the possibility of producing a variety of molecular machinery shapes including molecular rotors, gyroscopes, propellers, ratchets, gears, toothed cogs, etc. They are heavily used in drug-delivery, drug targeting, DNA directed assembly, molecular building blocks for synthesis of high temperature Polymers and in host-guest chemistry for modeling supramolecular complexes.


References:
Advances in Chemical Physics Vol. 136, pp. 207-258, 2007
and
www.diamantane.info/index.html