Scientists at The University of Nottingham
have discovered a way to control how tiny flat molecules fit together in a
seemingly random pattern.
The researchers have been studying
molecules which resemble tiny rhombus/diamond-shaped tiles, with a side length
of around 2 nm.
The fundamental research, published in Nature Chemistry, has shown that they
can prompt the ‘tiles’ to form a range of random patterns by adjusting the
conditions in which the experiment is conducted.
Lead author Andrew Stannard, in the
University’s School
of Physics and Astronomy
says: “To construct some sort of nanoscale device comprised of molecules, one
needs to understand how those molecules will interact with one another.
“Typically, a useful device would be one in
which the molecules arrange themselves in some perfectly ordered, regular
manner. What we have studied here is almost the complete opposite—we have
purposely tried to make the assemblies of molecules as random as possible.
“However, if we can gain a complete
understanding of how randomness and disorder arises in these types of molecular
structures, we can better understand how to eradicate that disorder when we
want to create something functional.”
Tilings of various geometrical shapes have
interested scientists, mathematicians, and artists for centuries, and a wide
range of tilings can be seen adorning many medieval architectural structures,
as well as for practical purposes in our more modern kitchens and bathrooms.
But tile effects occur naturally within
nature and science too and tilings of rhombuses are of particular interest to
physicists, mathematicians and computer scientists because of their ability to
form both periodic (regular, repeating patterns) and nonperiodic (random)
patterns.
The Nottingham scientists have demonstrated
for the first time that the generation of molecular rhombus tilings with varying
degrees of orderliness—some very random, some very ordered—can be achieved by
varying the conditions of the experiment in which they are created.
The achievement is all the more remarkable
considering the range of experimental conditions in which this can be achieved
is extremely narrow, requiring the scientists to achieve a delicate balance
between energy and entropy—the subjects of the first and second laws of
thermodynamics, some of the fundamental laws of physics and, in the case of
entropy, are linked to order and disorder within a thermodynamic system.
