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Tied up in a molecular knot

Published online 16 March 2016

Scientists synthesize knotted molecular structures using anions. 

Nadia El-Awady

Scientists have successfully synthesized molecular knots and links that could help in understanding biological processes and in detecting environmental pollutants.

The international team, including researchers from New York University Abu Dhabi (NYUAD), used negatively charged atoms — anions — as templates to synthesize three types of molecular knots and links in solution.

They found their synthesized trefoil knot, a single chain of molecules overlapping itself in an overhand fashion to form a three-leafed-clover-shaped knot, can act as an anion receptor.

“Many anion receptors have been designed and reported; however, few of them have been water soluble,” says synthetic chemist Ali Trabolsi from NYUAD. “The importance of being able to work in [solution] is that these structures can later be tested in biological processes, such as transporting anions to cells.”  

Knots are found in DNA, proteins and in man-made polymers such as rubber. It is thought they give interesting properties to these compounds, such as elasticity.

“These properties, combined with their anion binding ability, could bring about [synthetic] membrane-like materials with novel properties,” says Trabolsi.

They could also play a role in the detection of pollutants in solution.

The team’s method for synthesizing the knots and links has already been used by other scientists for further research. Their ultimate goal is to prepare new polymers and gels based on the knotted structures for a variety of useful applications.


Trabolsi, A. et al. [C–H···anion] interactions mediate the templation and anion binding properties of topologically non-trivial metal—organic structures in aqueous solutions. Chem. Sci. (2015).