Chemistry

Knotty questions in molecular assembly

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Science  27 Jun 2014:
Vol. 344, Issue 6191, pp. 1477-1478
DOI: 10.1126/science.344.6191.1477-d

How would you tie a knot if you couldn't touch either end of the rope? In the past few years, chemists have solved that problem at the molecular scale by precisely designing strand fragments, then luring them into mutually overlapping arrangements around metal ions. Ayme et al. now have tested the limits of that approach, exploring how subtle changes to the strands affect the distribution of knots produced in the reaction. Specifically, the authors mixed two types of strands that differed only by the presence or absence of two oxygen atoms. They found that the types sorted themselves remarkably well in combination with iron ions: The longer strands assembled into cross-shaped groups of four, the shorter strands into star-shaped groups of five.

Angew. Chem. Int. Ed. 53, 10.1002 anie.201404270 (2014).

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