20 septembre 2010
AMAZING NANO-NECKLACES OF MOLECULAR JEWELRY

We have designed, in collaboration with the Department of Molecular Chemistry at UJF, new one-dimensional organic objects capable of capturing metal ions. The color or visco-elasticity of these wires can be changed by simply applying a voltage.

 

Small organic molecules can self-assemble in different solvents to form rods or fibers. These molecules, furnished either with clamps (yellow in the figure) or cages (white), are capable of capturing transition metals (Fe, Co, Ni, Cu). According to whether the metals trapped in the clamps and cages are identical or different, we obtain homo- or hetero-metallic coordination polymers, whose properties are obviously different.

 

Furthermore, by varying parameters such as the type of solvent and the ionic strength, we can obtain different conformations of isolated molecules before polymerization into wires. By applying a selected voltage on the wire, it changes the oxidation state of the trapped metal and the conformation of molecules, and we thus obtain a molecular switch. Take the example of a cobalt trap (see figure): by oxidizing Co2+ to Co3+, a red gel is changed into a green liquid! This system is therefore both sensitive to chemical, mechanical and redox stimuli.  In the future, we plan to organize these organic wires onto nano-patterned substrates, as we do know for rigid nanowires, either metallic or semiconducting.

 

Further reading : A. Gasnier et al., Langmuir 25 (2009) 8751 ; A. Gasnier et al., Inorg. Chem. 49 (2010) 2592

 

Maj : 18/02/2014 (956)

 

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