Complexes acétylures mono- et polynucléaires du fer greffés sur silicium : vers des matériaux électrocommutables pour l'optique – METALLOSILIC

In this innovative and fundamental investigation, we will try to determine the scope that carbon-rich organometallics present for developing new functional materials in the field of optics. In this connection, redox-active electron-rich acetylides of the group 8 metals (iron notably) have been recently demonstrated to possess a strong potential at the molecular level for light beam modulation. Incorporated or grafted to an adapted silicon support, these fascinating organometallics should lead to functional materials or surfaces exhibiting very interesting properties for the "all-optical" treatment of light beam-driven information. Thus, in the field of optics, the high stability of the organometallic buliding blocks under several redox states allows for simple electrochemical generation of families of highly polarizable compounds exhibiting widely different absorptions in the different redox states, this peculiar feature also translates into widely different non-linear optical properties. Once grafted on silicon via their pendent terminal alkyne functionality, these compounds will give rise either (i) to new redox-switchable hybrid materials that might be used in waveguides or optical gates or (ii) to second harmonic generation (SHG)-active surfaces. The more challenging development of commercially-viable integrated new electro-commutable devices is clearly a longer-standing prospect which should nevertheless be envisioned as a clear perspective of this exploratory work. Also, it must be emphasized here that this project, centred on Rennes, will be conducted by a pluri-disciplinary team of researchers allying chemists and physicists with good international recognition and possessing very complementary skills. More precisely, the objectives are: 1. To develop mild and versatile ways to covalently graft selected electron-rich acetylides on silicon surfaces. 2. To investigate the kinetics of electron transfer between the grafted compounds and the surface depending on the nature of the chemical bond with the surface and establish the possibility to control the redox state of the immobilized organometallic guests using the supporting material as an electrode. 3. To compare the optical and electronic properties in the various redox states of these hybrid materials and try to delineate precisely the potential of silicon-based hybrids for making electro-switchable waveguides, electro-switchable SHG-active surfaces or other related devices. 4. To rationalize the experimental observations and properties of the hybrid materials by quantum calculations (DFT) conducted on molecular models but also on model surfaces incorporating these molecular models.