[extropy-chat] Smalley, Drexler and the monster in Lake Michigan

[Eugen Leitl]

On Thu, Dec 11, 2003 at 06:15:35AM -0800, Robert J. Bradbury wrote:

> Hmmmm....  If that were true then one should not be able to make
> buckyballs or buckytubes (as I believe they have strained bonds).

Small strained (even highly so) cages are no problem (prismane, cubane,
dodecahedrane). If you look at the principles in their synthesis:

	http://www.ch.ic.ac.uk/local/projects/b_muir/Cubane/Cubanepro/Synthesis.html

you'll see everything occurs on a local scale. This doesn't
apply for the fine-motion controller. (I've just have taken a
look at it again): you can easily make the subsystems, albeit
not in a great yield. It's doable to get annelated rings to
self-assemble in a pi-complex, and you can get a nanotube
into the lumen, and fixate the ends (not with diamondoid
plates, though, and you can't get SWNT monofragmented by
a given size). There's not at all much strain present in the
structure, but all of it prevents ligation into final shape,
so it won't happen in a stochastic synthesis.

I can go into more detail, but it's not required, as no
one assumes organic synthesis will be used for bootstrap
for components of this complexity. Engineered enzymes
reach much further, but we can't de novo design enzymes
for specific tasks yet. 

> Cubane is perhaps the ultimate example and it is produced using
> chemical synthesis.

I'm wasn't talking about merely strained molecules.
 
> I did not say that one would have a high yield -- since some
> parts of nanotech development may be a bootstrapping process
> you may only need one copy of something.
> 
> A related question -- do you know of a program/utility that
> can show the degree of bond strain?

Not something you just can plug a random structure into,
and expect meaningful values. It is possible to estimate
strain for a fine motion controller, but it's not the absolute
values which make the synthesis prohibitive.

If this still interests you, there are problems and references
aplenty at

	http://chemistry.gsu.edu/glactone/modeling/Magid/strain/strain.html

-- Eugen* Leitl <a href="http://leitl.org">leitl</a>
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