By Rachel Vowcicefski (Email Rachel at: firstname.lastname@example.org)
SC Chief Copy Editor
Recently, chemists have created a molecule whose 160 atoms loop over one another like a five-pointed star, creating the largest chemical knot yet. The molecule’s design, called a pentafoil, is the most complex knot synthesized from building blocks other than DNA.
Knowing how to make a pentafoil, its discoverers at the University of Edinburgh say, could lead to ways to make materials lighter, stronger or more flexible than before. As far as chemical knots go, the simplest knot is the “unknot,” which is a loop that does not cross over itself. The next simplest is a “trefoil,” which has three crossing points and was first synthesized in 1989.
The pentafoil is now the largest chemical knot to be synthesized. In order to make the pentafoil, the scientists took negatively charged chloride ions and added ingredients such as positively charged iron ions and long chains of carbon and other atoms. They then chemically programmed the whole thing to assemble itself. Five of the chains looped over one another and attached with five iron ions. These complexes then attached to the center chloride ion to create the finished pentafoil.
This molecule turns out to be interesting for more than just its shape. The pocket in the middle of the knot where the chloride ion sits is a perfect fit physically and chemically because when it is removed, the molecule desperately attempts to regain the chloride ion, making it possible for the molecule to be used as a sensor to detect chlorine in surrounding solution. These molecules may then eventually be used to dechlorinate a solution if added to a reaction in excess.
The creation of bigger knots could also help scientists uncover general rules of knotted molecules such as rubber, which gets much of its stretchiness from knots within its polymer chains.
This discovery could lead to a better understanding and integration of chemical knots in creating new materials for every day things like clothing materials or electronics. By understanding the complexity of the creation of this large knotted molecule, larger ones can eventually be synthesized and can be used for the betterment of the world.