Chemistry Reference
In-Depth Information
transformations to connect their components to each other or to other MIMs and
molecules, such as V
€
ogtle's pretzelanes, [1]rotaxanes, and bonnanes (see Sect.
3.2
),
knotaxanes [
213
], as well as our stepwise route [
214
] to rotacatenanes (Fig.
22c
).
Even more than being a road to new architectures, the boon of post-synthetic
flexibility has been in the arena of molecular switches and machines, which we
discuss in Sect.
4.5
. In short, a simple functional group on a MIM can be an elegant
way to integrate it.
4.4 Complexity and Emergence
In contrast to the pleasure of comprehension, harmony, and tidiness that goes with
the connected topics of simplicity and elegance, is the pleasure of surprise and
learning that accompanies the related concepts of complexity [
215
] and emergence
[
216
]. In complexity, those pleasures that ignite at the sight of a simple molecule
are silenced and replaced by laborious efforts to grasp and discern, or perhaps plain
confusion. Beauty must be sought in tension and challenge rather than in simplicity
and harmony. Emergence, however, is immediately pleasing when we recognize it:
that “Eureka!” moment, the realization that the whole is greater than the sum of its
parts, that the output could not have been predicted by inspection of the input.
Emergence arises out of complexity; it is the diamond at the bottom of a dark mine.
We are in danger of conflating “complex” with “complicated”. While there is
undoubtedly beauty to be found in both, in science they have different meanings.
Complexity is related to chaos - dynamic, non-equilibrium, nearly unpredictable
phenomena. Chaos theory was borne out of meteorology and mathematics and is
conceptually (and hypothetically) demonstrated by the famous “butterfly effect,”
where the simple flap of a butterfly's wings can be enough to trigger catastrophic
weather thousands of miles away. Complexity and chaos is a growing and highly
multidisciplinary field of research. By contrast, “complicated” only refers to things
that are, well
complicated - having many parts or intricacies, perhaps.
Again we find ourselves in muddy waters, where we must admit that there is a
prominent subjective air to this business of complexity and emergence. What is
complex to one person might seem only complicated to another, wiser person. What
is emergent now will not be emergent in 100 years when it is more deeply
understood. Whitesides [
215
] has noted of complexity that even the simplest
organic reactions are complex when considered rigorously; reactants have an
enormous variety of conformations and interactions with solvent molecules, ions,
other reactants, and so on. Hence, chemistry is an empirical science; we understand
these truly complex reactions by correlating structure and reactivity in the light of
loads of data. In that sense, emergence might be an area of chemistry where our data
is too incomplete to give us a reliable understanding of structure-response
relationships. With that disclaimer, we share a few examples that we find of
emergence in MIMs.
...
