ChevronTexaco Corp., announced the discovery of "a new class of molecular building blocks called higher diamondoids. These nanometer-sized carbon-based materials are found in petroleum and are potentially instrumental to advancing the field of nanotechnology."

The building blocks found in petroleum are "higher diamondoids," clusters of 4 to 11 diamond-crystal cages fused together to give molecules of ~1 to 2 nm in size. Each of these diamond-crystal cages is an adamantane cage, in which 10 C atoms are fused into three rigid rings so that they maintain the same tetrahedral spatial relationships to each other that they have in a diamond crystal, with the 16 dangling bonds terminated with H atoms. The lower diamondoids, with 1, 2, and 3 cages were previously found in petroleum and have been chemically synthesized, but the higher diamondoids were unknown before this discovery. All of the higher diamondoids come in several different shapes, including straight rods and left- and right-handed helices.

Gary Masada, president of ChevronTexaco Energy Research and Technology Co., is quoted on the usefulness of these building blocks for nanotechnology, "Diamondoid molecules possess superb characteristics for nanotechnology: rigidity, durability, multiple shapes and sizes, and potential for precise self-assembly."

And from Greg Vesey, president of ChevronTexaco Technology Ventures, "These building blocks offer untapped potential for significant advances in the fast-growing area of nanotechnology. We are pleased to have found these potentially valuable materials in petroleum and want to actively encourage research and development on higher diamondoids and their applications."

The potential of these building blocks is taken seriously enough that a new business unit was formed to commercialize them.

ChevronTexaco Technology Ventures announced that it has formed MolecularDiamond Technologies, a new business unit, which will make small quantities of proprietary higher diamondoid materials commercially available for research and development in mid-year 2003.

Commenting Dec. 5, 2002 on the Nature materials update web site [Nanodiamonds in oil, Natural petroleum has been found to harbour a menagerie of hydrocarbon 'diamondoid' molecules made from rigid fragments of the diamond crystal lattice. -- free registration required], Philip Ball, a consultant editor for Nature and Writer in Residence in the Chemistry Department of University College, London, pays special attention to the potential of higher diamondoids in molecular nanotechnology.

But perhaps most intriguing of all are the possibilities for nanotechnology. Many of the hypothetical cogs, gears and other nanomachine parts discussed in K. Eric Drexler's Nanosystems (1992) were fashioned from diamondoid frameworks. Although it remains unclear whether molecular components this complex could be synthesized, and whether in any event rigidity is really so necessary or desirable for many applications of nanoscale mechanics, it is nevertheless possible to imagine some intriguing uses for these strong and stable diamondoid nano-objects.

The ChevronTexaco press release contains a link to a PDF of the research paper, which was published online by ScienceExpress Nov. 28, and in print in the Jan. 3, 2003 issue of Science, vol. 299, pp. 96-99.

Isolation and Structure of Higher Diamondoids, Nanometer-Sized Diamond Molecules

J. E. Dahl, S. G. Liu, R. M. K. Carlson

We exploited the exceptional thermal stability and diverse molecular shapes of higher diamondoids (C22 and higher polymantanes) to isolate them from petroleum. Molecules containing 4 to 11 diamond-crystal cages were isolated and crystallized, and we obtained single-crystal x-ray structures for representatives from three families. Rigidity, strength, remarkable assortments of three-dimensional shapes, including resolvable chiral forms, and multiple, readily derivatizable attachment sites make them valuable nanometer-size molecular building blocks.

Further perspective and more details are provided by press coverage of the discovery. The New York Times [A Carbon-Atom Combo: Diamonds Found in Crude Oil, by Kenneth Chang, Dec. 3, 2002, free registration required] stressed the application to nanotechnology.

But the infinitesimal size could be just what scientists want: potential building blocks for the construction of molecular-scale machinery.

"A good analogy for these are Legos," said one of the researchers, Dr. Jeremy E. Dahl, an organic geochemist at ChevronTexaco. "It's a brand new set of materials that no one has ever looked at."

...

Nanotechnology researchers have for years imagined what they might be able to make with diamondoids, but until now they have been able to explore those ideas only with computer simulations.

"It creates quite an opportunity for someone thinking how to construct something on molecular scale," Dr. Carlson said. "They're about as rigid as you can get."

And from the San Francisco Chronicle [Miniature diamonds found in oil, by Carolyn Said, Dec. 3, 2002]

The carbon materials come in a wide variety of shapes, conduct heat rapidly and are very rigid and stable, Qureshi [Warqar Qureshi, who heads MolecularDiamond Technologies, the new ChevronTexaco unit that will try to find applications for the diamondoids] said. Those properties -- plus their minute size -- make the diamondoids potentially useful building blocks for molecular-size machines, or nanotechnology.