Figure 8.

Schematic illustration of a ligand exchange of DDT for S^2– and subsequent phase transfer from apolar toluene to polar formamide. The Cu_2–xS nanocrystals prepared by hot-injection synthesis have a less dense ligand layer than the nanocrystals prepared by heating-up synthesis due to the removal of TOPO from the surface of the nanocrystal after synthesis and washing. Consequently, the nanocrystal surface is more accessible to the incoming ligands, resulting in a faster ligand exchange. Upon ligand exchange on nanocrystals prepared by hot-injection synthesis, all thiolate ligands are removed from the nanocrystal surface. In contrast, upon ligand exchange on nanocrystals prepared by heating-up synthesis, some thiolate ligands remain on the surface.