プラトンの正多面体の一つ、１２面体をSi20 dodecahedronとしてone step合成したという。正１２面体や正２０面体（ビールス）は生物界にも多い。
uwgb.edu/dutchs/symmetry/platonic
Braarudosphaera bigelowii石灰質ナノプランクトン 円石藻 （正１２面体の炭酸カルシウム（coccosphere）を形成する単細胞真核藻円石藻類）
白亜紀初期から生息。 年間３６０億トンの有機物を生産。
ina.tmsoc.org/CODENET/GuideImages/INcerbsph/source/133-02
山形大学大学院. 今野進
30 years after C60: Fullerene chemistry with silicon opens new possibilities in semiconductor industry
Date:March 18, 2015 sciencedaily.com
Source:Goethe-Universität Frankfurt am Main
Summary: Chemists have managed to synthesize a compound featuring an Si20 dodecahedron. The long strived-for silicon dodecahedron has been synthesized at room temperature.
Source:Goethe-Universität Frankfurt am Main
Summary: Chemists have managed to synthesize a compound featuring an Si20 dodecahedron. The long strived-for silicon dodecahedron has been synthesized at room temperature.
Goethe University chemists have managed to synthesise a compound featuring an Si20 dodecahedron.
The Platonic solid, which was published in the "Angewandte Chemie" journal, is not just aesthetically pleasing, it also opens up new perspectives for the semiconductor industry.
The discovery of the soccer ball-shaped C60 molecule in 1985 was a milestone for the development of nanotechnology.
In parallel with the fast-blooming field of research into carbon fullerenes, researchers have spent a long time trying in vain to create structurally similar silicon cages.
Goethe University chemists have now managed to synthesise a compound featuring an Si20 dodecahedron. The Platonic solid, which was published in the journal Angewandte Chemie, is not just aesthetically pleasing, it also opens up new perspectives for the semiconductor industry.
The Si20 dodecahedron is roughly as large as the C60 molecule.
However, there are some crucial differences between the types of bonding: All of the carbon atoms in C60 have a coordination number of three and form double bonds.
In the silicon dodecahedron, in contrast, all atoms have a coordination number of four and are connected through single bonds, so that the molecule is also related to dodecahedrane (C20H20).
"In its day, dodecahedrane was viewed as the 'Mount Everest' of organic chemistry, because it initially could only be synthesized through a 23- step sequence.
In contrast, our Si20 cage can be created in one step starting from Si2 building blocks,"
explains Prof. Matthias Wagner of the Goethe University Institute of Inorganic and Analytical Chemistry.
The Si20 hollow bodies, which have been isolated by his PhD student, Jan Tillmann, are always filled with a chloride ion.
The Frankfurt chemists therefore suppose that the cage forms itself around the anion, which thus has a structure-determining effect.
On its surface, the cluster carries eight chlorine atoms and twelve Cl3Si groups.
These have highly symmetric arrangements in space, which is why the molecule is particularly beautiful. Quantum chemical calculations carried out by Professor Max C.
Holthausen's research group at Goethe University show that the substitution pattern that was observed experimentally indeed produces a pronounced stabilisation of the Si20 structure.
In future, Tillmann and Wagner are planning to use the surface-bound Cl3Si anchor groups to produce three dimensional nanonetworks out of Si20 units.
The researchers are particularly interested in the application potential of this new compound:
"Spatially strictly limited silicon nanoparticles display fundamentally different properties to conventional silicon wafers,"
explains Matthias Wagner. The long strived-for access to siladodecahedrane thus opens up the possibility of studying the fundamental electronic properties of cage-like Si nanoparticles compared to crystalline semiconductor silicon.
Story Source:
The above story is based on materials provided by Goethe-Universität Frankfurt am Main. Note: Materials may be edited for content and length.
Journal Reference:
1.Jan Tillmann, Josef Heinrich Wender, Ute Bahr, Michael Bolte, Hans-Wolfram Lerner, Max C. Holthausen, Matthias Wagner. One-Step Synthesis of a [20]Silafullerane with an Endohedral Chloride Ion. Angewandte Chemie International Edition, 2015; DOI: 10.1002/anie.201412050