Researchers in the UK and Germany has uncovered the mechanism behind how one of the most powerful chemical structures develop by itself, the biggest wheels of a molecule made of molybdenum oxide, spontaneously produce by itself. These findings have important implications kelihatnnya in memanupulasi assembly reaction by itself and equip a new way to create a useful molecular architecture. Approximately 15 years ago, Achim Müller and his colleagues at the University of Bielefeld in Germany showed that a simple mixture of sodium molybdate, water and a reduction in low pH agents spontaneously form molecular wheel donut-shaped molybdenum oxide.
Almost 4nm diseberangnya there is more than a distance larger than the structures seen before, and showed the unique class of molecules with many potential applications for materials and nano sciences. However, the mechanism of self-assembly remains unknown.
Today, Lee Cronin of the University of Glasgow in the UK and his colleagues have revealed this mystery by solving the reaction in the flow space. Here the introduction into the space below the reactant flow. Addition of a constant of the reactant at the entry point to develop a stable condition, allows the production of the initial reaction to accumulate close to the point of entry. In part this room opara researchers looked at crystals precipitated from solution. X-ray crystallography showed that the crystal - a flat disc-shaped crystal that includes 186 molybdenum atoms, after the show includes 36-Mo in the central core that contains the 150-Mo-hole wheels.
When the wheels are arranged, the addition of eight electrons increase the repulsion between the ring and the template, resulting in a collection of 36-Mo released wheels archtypal molybdenum has a large negative charge - this is reduced to 28 electrons, where we determine that the wheel - the wheel of molecular stood at 20 electrons flow system is reduced. This shows that the collection of 36-Mo serves as a template around molybdenum combined into a ring and two atomic units is held in common - the same by the ions - sodium ions and hydrogen bonds. Under reduced conditions, electrostatic repulsion eventually reach the point where the center wheels are removed: serves as the smallest set of templates that would create a temporary guest host and then leave.
Prove the usefulness of this approach in other systems open the assembly itself. What we have in the show is to track these complex reactions that produce molecular arsitektuur unusual, we can trap the continued and learn how to start manupulated known systems and designing new anymore.
John Errington, a specialist in nanostructured metal oxides at Newcastle University in England, said that the implications of this new job has been great. 'The ability to direct nanoskala structure obtained from a dynamic mix of constitutional molecular building blocks of metal oxides has been the biggest challenge since Müller and coworkers first time reveal the origin of the form "big ring" great reduce molybdate solution, "said Errington. 'Use of the brightest of the flow of chemical science seems to provide the basis for a general synthetic strategy that will further broaden the areas of interest in the science of chemistry. "
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