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Chemistry

Taking a Deep Breath

The organic world's monopoly on one of its most basic activities–breathing–has been broken with the help of a novel material developed in the lab of chemist Gérard Férey.1,2 Part of a new family of solid crystals, the material is a hybrid of organic and inorganic molecules. By placing it in a liquid, the crystal behaves like a human lung, expanding in size, “breathing in” specific solvents in the fluid, and then returning to normal size by expelling them, with its overall shape unchanged. “This is really a spectacular occurrence because of the amount of variation in its dimensions. It can increase to three times its normal size,” adds Férey.

The material, which was developed with Christian Serre, a CNRS coworker in Férey's lab, is a chromium (III) dicarboxylate. The elasticity of the material comes from long organic molecules linked to each other by chromium metal molecules that provide the final shape. The long organic molecules are chains, whose links Férey likens to “knee joints,” letting the compound expand and absorb specific liquids in a controlled manner. “Depending on the solvent absorbed, the kinetics can change–it can absorb for three minutes or three days,” he says. By changing the nature of the organic components of the material, it may also be possible to tailor what it can absorb: “It's the equivalent of distillation at room temperature.”

And while Férey says that he expects to be able to produce new breathing solids with even greater capabilities, he is quite reserved on the lab's future prospects; they have developed and patented other porous solids. “Our products have a double appeal: We do lots of physical chemistry, with a global approach. But we can also expect modest applications in the field of climate change– not only to capture carbon dioxide, but possibly also even to destroy it,” he adds.

Férey credits much of his success to his team's use of complex computer simulations to predict the properties of experimental polymers. A computer simulation will usually produce three or four potential combinations of inorganic and organic materials, which, when combined with experimental and theoretical knowledge, lets Férey control what he produces before experimentation. “After that, it's really just like Lego,” he concludes.

 

Mark Reynolds

 

Notes :

1. Institut Lavoisier (CNRS / Université de Versailles Saint-Quentin-en-Yvelines).
2. C. Serre et al., “Role of Solvent-Host Interactions That Lead to Very Large Swelling of Hybrid Frameworks,” Science. 315: 1828-30. 2007.

Contacts :

Institut Lavoisier, Versailles.
> Gérard Férey,
gferey@wanadoo.fr
> Christian Serre,
serre@chimie.uvsq.fr


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