Ligands capping

PBE dendrons coordinate to the surface of II-VI semiconductor nanocrystals (e.g., CdSe [33] and CdSe/ZnS core/shell structure [34, 35]) to modulate the photoluminescence of the nanocrystals [32]. Trioctylphosphine oxide (TOPO)-capped II-VI semiconductor nanocrystals of several-nanometers diameter have been synthesized by a pyrolysis reaction of organometallics in TOPO [33-35]. The capping ligand (TOPO) can be replaced by stronger ligands such as thiol compounds [36], suggesting that dendrons bearing sulfur atom(s) at the focal point replace TOPO as well. 

However, as the cluster becomes larger there comes a point at which it becomes more accurate to consider it to be a nanoparticle, possibly with an exterior coated with a layer of capping ligands. We consider a diameter of 1 nm to be a reasonable although arbitrary value for differentiating between clusters and nanoparticles. ... 

To compare NEt3 with NOct3, there was no obvious effect to regulate the size distribution of nanoparticles, because they could not function as a capping ligand of nanoparticles due to their weak coordination to silver in the growth process of silver nucleus [17]. 

High-Temperature Crystallization The size-tunable optical and electronic properties of semiconductor nanocrystals are attractive for a variety of optoelectronic applications. In solution-phase crystallization, precursors undergo chemical reaction to form nuclei, and particle growth is arrested with capping ligands that... 

In the absence of capping ligands, polymeric alkynylmercury derivatives can be readily prepared. Polymer 57 is formed by reaction of HgC with 9,9-bis(4-ethynylphenyl)-fluorene in a basic methanolic solution. This polymer, whose average molecular weight (/I7W) is only 8,900, shows a strong triplet emission of the organic chromophore enhanced by the presence of the mercury heavy atom.69... 

Figure 15.1 Transmission electron microscopy images showing iridium nanoparticles prepared in four different capping ligands, (a) Oleic acid/oleylamine (b) TOAB ...

---