different parts of a solid sample
. The authors
turned to nanophysics for an answer to this
: specifically, the fact that a tiny
crystal comparable in size to the wavelength
of ultraviolet light (around 200–400 nano-
metres) can provide an environment homo-
geneous enough to minimize sample effects.
Applying a technique developed by their own
, they used an aqueous nanocrystalline
suspension to trap all the photons from the
ultraviolet light source. Taking their earlier
measurements on a related solid ketone as a
reference, they were able to calculate an accu-
rate value for the quantum yield of their new
That value was 3.3. For one photon to be
activating more than one molecule (a quantum
yield of 1.0), the reaction must be proceeding
through a remarkable quantum chain pro cess
with electronic excitations cycling through
the crystal as bonds on different rings open
and close. Any energy not used in the chain
pro cess probably led to loss of the included
water (the crystal was prepared as an aque-
ous ‘mono hydrate’),
the crumbling of the
crystal, and recrystallization of the acetylene
In 1959, in his famous talk ‘There’s plenty of
room at the bottom’,
Richard Feynman raised
what was, in retrospect, an irresistible ques-
: “What would the properties of materials
be if we could really arrange the atoms the way
we want them?” Answers to this question can,
and have, been sought in all states of matter
— gas, liquid and solid. By effectively ‘spring-
loading’ a molecule so that, when touched
by light, it transferred its energy to a nearest
establish a new
connection between unimolecular and bimo-
lecular reactivity. We can now start to wonder
what further use we might make of the tech-
nique; whether, for example, the signal ampli-
fication provided by its domino-like behaviour
might be useful for sensor-based materials
and applications. With our rapidly growing
knowledge of the structures and properties of
, Ruzicka’s morgue-like crystals
will probably continue to reveal themselves as
surprisingly lively places.
Leonard R. MacGillivray is in the Department of
Chemistry, University of Iowa, Iowa City,
Iowa 52242, USA.
Dunitz, J. D., Schomaker, V. & Trueblood, K. N.
2. Desiraju, G. R.
Angew. Chem. Int. Edn
3. Kuzmanich, G.
et al. J. Am. Chem. Soc.
4. Choi, T., Peterfy, K., Khan, S. I. & Garcia-Garibay, M. A.
J. Am. Chem. Soc.
5. Daglen, B. C., Harris, J. D., Dax, C. D. & Tyler, D. R.
6. Buc˘ar, D.-K. & MacGillivray, L. R.
J. Am. Chem. Soc.
7. Veerman, M., Resendiz, M. J. E. & Garcia-Garibay, M. A.
8. Gillmore, J. G.
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