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Self Assembly. The Science of Things That Put Themselves Together. By JohnA. Pelesko

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Self Assembly
The Science of
Things That Put
Together. By John A.
Pelesko. Chapman
& Hall/CRC, Boca
Raton 2007.
336 pp., softcover
£ 28.99.—ISBN
Physical laws can direct the flow of
matter toward a more organized state.
This idea underlies a range of phenomena that are observed in many different
scientific disciplines across widely varying scales of distance. Many chemists are
fascinated by self-assembling systems,
and some have made major contributions to understanding phenomena of
self-assembly. In order to understand
and integrate the experiences of
researchers thinking about self-assembly in other disciplines—physics, biology, materials, information science, and
various kinds of engineering spring to
mind—it would be useful to have an
engaging and accessible textbook presenting an overview of self-assembly in
all its interdisciplinary splendor. The
provision of such a textbook is the task
that author and mathematician John A.
Pelesko sets for himself in writing Self
Assembly—The Science of Things That
Put Themselves Together.
The book starts out well enough,
conveying the sense of wonder felt when
one is faced with a complex, structured
system that has managed to put itself
together from simpler bits. The importance of the field is underlined convincingly, by noting early in the discussion
that self-assembly is used as a key
construction technique in nanotechnology. Unfortunately, reading further
reveals a fundamental fuzziness of presentation, made particularly evident to
this reviewer in the chemical examples
The author has chosen examples
spanning a wide range of disciplines.
There is much food for thought here—
my own horizons were broadened by the
author&s thought-provoking discussions
of the early work of Penrose and Penrose[1] on a self-reproducing system and
of the interface between self-assembly
and computation, among other topics.
However, it is clearly difficult to tie
such a wide-ranging body of work into a
coherent whole. Each discipline has its
own perspective and vocabulary, and the
application of one field&s point of view
to another can lead to cognitive dissonance, as when the author divides selfassembling systems into “inorganic” and
“organic” examples, meaning nonliving
and living. These terms have very different meanings to a chemist, and opportunities for misunderstanding multiply
with errors—images presented as the
structures of an a helix and a b sheet are
incorrect, and the author refers to
Mirkin&s use of “aluminum” templating
in the creation of metal–polymer amphiphiles, whereas the material used was
Key concepts of thermodynamics
are incompletely explained or missing.
Although the minimization of free
energy is presented as a principle underlying self-assembly in different systems,
the notion of a thermodynamic driving
force is not defined in terms of energy
minimization. The idea of equilibration
is instead presented as the “driving
force”, one of “Nature&s four key components of a self-assembling system”
(together with “structured particles”,
“binding forces”, and “environment”).
The “driving force” is defined thus: “In
order for self-assembly to occur the
particles must interact stochastically.
This driving force in the system is
usually thought of as noise [author&s
emphasis]. This may be thermal noise,
physical oscillation of the system, or
driving via electromagnetic fields”.
While this reviewer does not disagree
with the four key components presented, the author&s description of ther-
4 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
mal noise as a driving force is at odds
with the idea of a thermodynamic driving force that presents a “downhill”
direction, in which a system may flow
so as to minimize free energy.
Ethylene polymerization and diffusion-limited aggregation are presented
as examples of self-assembly, without
mentioning the essential feature that
makes one doubt their suitability for
inclusion in this book: they occur under
kinetic control (thus removing them
from consideration under a definition
by Whitesides),[2] yet do not fall into
Lindsey&s class of “irreversible selfassembly” processes,[3] in that they are
not deterministic. The inputs and the
self-assembly process do not define a
single output structure; on the contrary,
a very large set of possible products
could result from a successful polymerization reaction, for example. While it is
possible to define self-assembly broadly
enough to include such phenomena,
such a definition risks falling into a
trap identified by Whitesides (“Is Anything Not Self-Assembly?”),[2] in which
the concept of “self-assembly” is
stretched so far as to lose its utility.
The book succeeds as a cabinet of
curiosities touching upon a variety of
phenomena grouped under the banner
of self-assembly. However, it fails to
provide sufficient thread to bind these
examples together into a conceptually
coherent whole. Although the book
proved enjoyable to read, its lack of
conceptual clarity could make it a difficult textbook. Chemistry students, in
particular, might find it hard to bridge
the gap between the material presented
in this book and the contents of their
chemistry courses.
Jonathan R. Nitschke
Department of Chemistry
University of Cambridge (UK)
DOI: 10.1002/anie.200885572
[1] L. S. Penrose, R. Penrose, Nature 1957,
179, 1183.
[2] G. M. Whitesides, B. Grzybowski, Science 2002, 295, 2418 – 2421.
[3] J. S. Lindsey, New J. Chem. 1991, 15,
153 – 180.
Angew. Chem. Int. Ed. 2008, 47, 6108
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pelesko, self, assembly, things, put, john, together, science
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