The properties of matter on the nanoscale have attracted ever-increasing interest in recent years, as new properties are expected for objects of intermediate size between molecules and bulk materials. This has given rise to numerous fundamental studies in the fields of optics, magnetism, nanoelectronics and catalysis. For these objects, typically ranging in size from 1 to 10 nm, surface chemistry is very important, as it governs not only chemical properties but also physical properties, notably optical and magnetic.
Organometallic solution chemistry techniques enable nano-objects to be synthesized under very mild conditions, with a perfectly controlled surface state. The addition of organic molecules (ligands) to the surface of these particles will enable:
1) stabilize the particles
2) direct their chemical reactivity,
3) modulate their physical properties,
4) control particle shape,
5) self-organization of particles in 2- or 3-dimensional superlattices, or even spontaneous crystallization of nanoparticles within 3D superlattices.
This concerns noble metals (Ru, Pd, Pt, Au), magnetic metals (Fe, Co, Ni), copper for microelectronics, main group compounds (ZnS, InP, Cd3P2, ...) and oxides (of iron, cobalt, zinc, tin, indium, ...) as well as alloys. Growth control can be "kinetic", by modifying the nucleation and growth stages, or "thermodynamic", by using a correction mechanism to obtain strictly mono-dispersed nanoparticles. This makes it possible to control the growth of isotropic or anisotropic nanoparticles: spheres, cubes, rods, wires, stars, sea urchins, fractal objects, and to fabricate complex nano-objects containing hetero-junctions: for example, gold on cobalt nano-rods or cobalt on CdSe nano-rods. Finally, nanoparticles can be grown in an organic or inorganic matrix, or with coordination polymers.
