Volume 94 Issue 47 | p. 11 | Concentrates
Issue Date: November 28, 2016

Chemoctopus has superlative redox powers

Metallodendrimer’s redox-active arms acting in unison has potential for multiple materials applications
Department: Science & Technology
Keywords: inorganic chemistry, octasilsesquioxanes, POSS, carborane

An octasilsesquioxane grafted with redox-active metallacarborane arms—we’ll call it a chemoctopus—could prove to be a versatile material for a host of sensing, catalytic, and biomedical applications (Inorg. Chem. 2016, DOI: 10.1021/acs.inorgchem.6b02394). Octasilsesquioxanes are intriguing Si8O12 cubes that are favorites of materials researchers because they are easy to make. The cagey framework ensures mechanical and thermal stability, and the easily functionalized silicon atoms give rise to tunable properties. Researchers have previously prepared electroactive metallodendrimers by attaching ferrocene units to silsesquioxane cores. But these compounds haven’t always been soluble in common solvents or exhibited uniform redox activity. In the new example, a team led by Rosario Núñez of the Institute of Materials Science of Barcelona grafted metallacarboranes to the silicon atoms of octavinylsilsesquioxane via olefin metathesis. The resulting octopus-like molecules exhibit high solubility in organic solvents, the researchers note, but in addition their electrochemical studies show that the pendant metallacarboranes act as independent, one-electron redox units that can transfer eight electrons at essentially the same potential. Developing such molecules that can uniformly store and transfer many electrons is an ongoing challenge in developing molecule-based electronics.


CORRECTION: On Dec. 5, 2016, this story was updated to correct the silsesquioxane formula. It should be Si8O12 rather than Si8O8 as originally stated.

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Credit: Courtesy of Rosario Núñez
Structure of an octasilsesquioxane with pendant metallocarborane groups.
 
Credit: Courtesy of Rosario Núñez
 
Chemical & Engineering News
ISSN 0009-2347
Copyright © American Chemical Society
Comments
Steve Ritter (Thu Dec 01 09:49:53 EST 2016)
UPenn chemistry improv poet Drew McGhie strikes again:

The Best Silly Con Job?

Octasilsesquioxane
Becomes a true chemoctopus
When grafted with metallocarboranes
And that is really good for us
For they have superior redox power
With eight equal arms attached
Like eight petals on a flower
With one-electron redox units unmatched
So eight electrons can be transferred
All at the same potential
An A+ thus must be conferred
On a process so consequential
Our thanks are due to Rosario Nunez
For this great advancement new
And to the Barcelona Institute goes the praise
For it will benefit more than a few

Andrew Roxburgh McGhie 12.01.2016
 (Thu Dec 01 16:51:45 EST 2016)
Typo Error: Si8O8 should be Si8O12.
Steve Ritter (Mon Dec 05 11:34:17 EST 2016)
Thanks for catching this mistake, it indeed should be Si8O12. We will correct the error.

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