It has been a beloved symbol for centuries, prized as an ornament found in engravings and embroidery, mosaics, and tattoos—and now as a molecule: Solomon’s knot, a motif consisting of two doubly intertwined rings.
A team of researchers from the University of California, Los Angeles (USA), and Nottingham Trent University (UK) have now used a self-organization process to get molecular building blocks to weave themselves into a Solomon-type knot.
“The secret of our success is the careful selection of metal ions and solvents,” revealed J. Fraser Stoddart in the journal Angewandte Chemie. “Although various molecular species compete with each other in solution, the Solomon’s knot wins out during the crystallization process simply because it crystallizes better.”
Systems consisting of individual molecular components that are not chemically bound to each other, but rather are tied together through purely mechanical means, are an enormous challenge for scientists. Stoddart, one of the pioneers in the area of supramolecular chemistry, has successfully produced a whole series of such structures. For example, he and his team have produced a system of molecules in the form of Borromean rings, whose name is derived from an Italian family that used such interlocked rings in their crest.
Stoddart’s Borromean rings are formed from an 18-component self-assembly process in which six organic pieces with two “teeth” and another six with three “teeth” grip six zinc ions, producing the mutually interlocked three ring system. Things get particularly interesting when zinc and copper ions are mixed in a 1:1 ratio: a 12-component self-assembly process ensues to interlock two rings twice over instead of three, resulting in the formation of a molecular Solomon knot, isolated upon crystallization. The four loops of the knot are stabilized by two copper and two zinc ions. In solution, there is initially an equilibrium between the different types of knots. During crystallization, the Solomon’s knot form is preferred over the Borromean rings.
“In the making of these exotic compounds, chemical bonds are being broken just as fast as they are being formed until the compound that feels the most comfortable emerges as the final product,” explains Stoddart.
Author: J. Fraser Stoddart, University of California, Los Angeles (USA), http://stoddart.chem.ucla.edu/
Title: A Molecular Solomon Link
Angewandte Chemie International Edition 2007, 46, No. 1, 218–222, doi: 10.1002/anie.200603521
The irresistible fragrance of dying vinegar flies
16.08.2017 | Max-Planck-Institut für chemische Ökologie
How protein islands form
15.08.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau
Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...
For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.
While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...
An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...
A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...
Researchers from the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science, the Italian Space Agency (ASI), and the Instituto Geofisico--Escuela Politecnica Nacional (IGEPN) of Ecuador, showed an increasing volcanic danger on Cotopaxi in Ecuador using a powerful technique known as Interferometric Synthetic Aperture Radar (InSAR).
The Andes region in which Cotopaxi volcano is located is known to contain some of the world's most serious volcanic hazard. A mid- to large-size eruption has...
16.08.2017 | Event News
04.08.2017 | Event News
26.07.2017 | Event News
16.08.2017 | Physics and Astronomy
16.08.2017 | Materials Sciences
16.08.2017 | Interdisciplinary Research