Addressable nano-materials


Keywords :

Nano-fibers, low molecular weight organic gelator, photochromism, AFM, single object microscopy and fluorescence spectroscopy


In a bottom-up approach, we use self-assembly to combine functional organic building blocks in order to obtain nano-objects and nanostructured materials for organic photonics, signal transduction, logic systems, opto-electronics and electronics. In order to address these nanostructures, efficient light-absorbing and emitting chromophores have been developed as building blocks.

In a first system based on linear acenes (Figure 1), the assembly leads to anisotropic nano-fibers and -ribbons which efficiently emit polarized light. The emission color can be tuned, and white-light achieved, thanks to efficient excitation energy transfer and exciton diffusion processes supported by a high molecular order. The weaving of nanofibers in the presence of organic solvents leads to the formation of organogels. (see also references 1,2, projects SMARTNET, CEFIPRA, MATPALM)

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Figure 1 : Micro- and Nano-objects based on linear acenes (anthracene, diphenyl anthracene and diphenyltetracene derivatives are represented) (click on image)

In a second system based on fluorenes (Figure 2), the assembly is directed by H-bonding interactions. Spontaneous formation of nano-spheres occurs in organic solvents, leading to highly fluorescent color-tunable and white-light emitting films. These provide promising dot-like emitters for future OLED applications. (ref. 3, project OLEV)

In a third system (Figure 2), a photopolic material, H-bonding interactions organize fullerenes in a double ribbon within microcrystals. A laser irradiation allows to write on the crystal by modifying the polarization of the emission, while its intensity is unchanged. Thereafter, the information can be read by a shorter laser excitation, but is only revealed when polarizers are used. (ref. 4, see also project HI-LIGHT)
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Figure 2 : (left) Directed H-bonding leads to Fluorescent, color-tunable Nano-spheres ; (right) A photopolic material based on a fullerene derivative (click on image)

The organic nano-structures are analysed by steady-state and transient fluorescence spectroscopy, as well as AFM. We are also equipped with a state-of-the-art fluorescence microscopy laboratory combining imaging, micro-spectroscopy, time-resolved and polarization confocal fluorescence microscopy, and AFM-coupled to fluorescence spectroscopy (see Techniques and Instruments).

Contacts :

Bassani, Dario ; Del Guerzo, André ; Desvergne, Jean-Pierre ; Pozzo, Jean-Luc

Selection of Publications  :

1. White Light Emitting Self-Assembled NanoFibers and their evidence by Micro-Spectroscopy of Individual Objects
C. Giansante, G. Raffy, C. Schäfer, H. Rahma, M.-T. Kao, A. G.L. Olive, A. Del Guerzo, J. Am. Chem. Soc., 2011, 133, 316-325.

2. Energy Transfer in Self-Assembled [n]-Acene Fibers involving ≥ 100 Donors per Acceptor
A. Del Guerzo, A. G.L. Olive, J. Reichwagen, H. Hopf, J.-P. Desvergne, J. Am. Chem. Soc., 2005, 127, 17984-17985.

3. Spontaneous generation of highly emissive RGB organic nano-spheres
K.-P. Tseng, F.-C. Fang, J.-J. Shyue, K.-T. Wong, G. Raffy, A. Del Guerzo, D. M. Bassani, Angew. Chem. Int. Ed., 2011, 50, 7032-7036.

4. Controlling the Emission Polarization from Single Crystals Using Light : Towards Photopolic Materials
G. Raffy, D. Ray, C.-C. Chu, A. Del Guerzo, D. M. Bassani, Angew. Chem. Int. Ed., 2011, 50, 9584-9588.

Book chapter on responsive materials :
Photoresponsive Gels in Molecular Gels. Materials with Self-Assembled Fibrillar Networks
A. Del Guerzo, J.-L. Pozzo, Eds. P. Terech and G. Weiss, Kluwer, 2005, 813-851.





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