Structurally Precise Silver- and Copper-Rich Superatomic Alloys – Nanoalloys

Nanoscale noble-metal particles have broad applications in catalysis, health sciences, molecular electronics, optical devices, etc. Among this large category of compounds, ligand-protected atom- and electron precise nanoclusters (NCs) known as superatoms are of prime fundamental importance owing to their intermediate position between simple molecules and larger metal particles. Whereas superatomic species are now well documented in gold coordination chemistry, only a handful of silver and very few copper analogues are known. It turns out that, during the last years, our two groups have been among a few to contribute to the development of these silver and copper superatom chemistries.
In particular, with the use of original dichalcogenolate ligands (L) we have developed a chemistry of [Ag21L12]+ and [Ag20L12] NCs which exhibits an unprecedented [Ag13]5+ centered icosahedron that is protected by 8 (7) additional Ag(I) atoms and 12 L- ligands. These stable closed-shell nanoclusters can be described as an 8-electron superatom with 1S2 1P6 configuration, as shown by our DFT calculations.
In the case of copper, we have recently been successful in isolating one of the very few known Cu superatoms, namely [Cu13(alkynyl)4(dtc)6]+ (dtc = dithiocarbamate) which is the first centered cuboctahedral copper NC with partial Cu(0) character (1S2 configuration).
Moreover, very recently we have been successful in alloying some of these Ag and Cu superatoms, which opens up the possibility of tuning the properties of these species. In this project, we aim at pushing the frontier of fundamental knowledge in exploring the burgeoning field of silver and the largely uncovered field of copper superatoms and more precisely of their alloys. Indeed, not only this new type of stable nanoclusters (and the bonding associated with) is fundamentally interesting per se, but also for their many potential properties. Our approach will be carried out on both the experimental (Taiwan) and theoretical (France) sides. We have been in the past years very successful in combining these two complementary and synergetic approaches. Based on our common experience and on very preliminary results we owe to investigate the following topics (synthesis, characterization and electronic structure):
- Mixed gold/silver nanoclusters stabilized by diselenolate ligands, obtained from galvanic substitution of silver by gold
- Mixed platinum/silver nanoclusters stabilized by dithiolate ligands obtained from galvanic substitution of silver by platinum.
- Copper-rich alloys of Ag, Au, Pd, Pt… stabilized by dithiolates and alkynyls
A special interest will be devoted to the rationalization of the structure and stability of the new species, as well as that of their electrochemical, optical and photoluminescence properties. It is likely that, as we already experienced it in the past, theoretical investigations will help to orientate synthesis in order to tune (optimize) some of the properties (including chemical composition and structural properties).