November 7, 2011
Tying Molecules In Knots
A research team headed by Professor David Leigh of the University of Edinburgh (UK) and Academy Professor Kari Rissanen of the University of JyvÃ¤skylÃ¤ (Finland) have made the most complex molecular knot to date, as reported in Nature Chemistry (DOI:10.1038/NCHEM.1193, published online Nov. 6 2011).
Knots can be found in DNA, proteins and even in the molecules that make up man-made plastics, where they often play an important role in the substance's properties (for example, 85% of the elasticity of natural rubber is due to knot-like entanglements in the rubber molecules chains).
Remarkably, the thread that is tied into the star-shaped knot is just 160 atoms in length — that is about 16 nanometers long (one nanometer is one millionth of a millimeter). The Edinburgh researchers used a technique known as "self-assembly" to prepare the knot in a chemical reaction. The building blocks are chemically programmed to spontaneously wrap themselves up into the desired knot. Making knotted structures from simple chemical building blocks in this way should make it easier to understand why entanglements and knots have such important effects on material properties and may also help scientists to make new materials with improved properties based on knotted molecular architectures.
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