Ligand Chemistry - Semiconductor Quantum Dots: Organometallic and Inorganic Synthesis - page 196

d n 1 y 4 n g | 6

Figure 6.8 Passivation of CdSe/CdS particles with alkene-terminated dendrons, box
formation and etching reactions. Reprinted with permission from
W. Guo, J. J. Li, Y. A. Wang and X. Peng, J. Am. Chem. Soc. , 2003, 125 ,
3901. Copyright 2003 American Chemical Society.

.

box. 240,241 The dendron boxes were found to be soluble only in aromatic or
polar organic solvents, whereas the parent dendrons were soluble in
a number of non-polar organic solvents.
The dendron boxes exhibited increased stability against HCl etching,
oxidation with H 2 O 2 , photo-oxidation and heating when compared to the
simple dendron-stabilised particles, although the core could be removed by
digestion with concentrated HCl,

. Despite the
increased stability, replacement of TOPO for the thiolated dendron almost
completely quenched the emission from CdSe particles. This was overcome
using CdSe/CdS core/shell particles, whose emission remained although
quenched to ca. 20% of the original value. Photobrightening, linked to
oxidation, was also observed and could, in some cases return the emission
back to its initial level.
The excellent stability a

leaving ' empty boxes '

orded by the RCM reaction limited the applica-
tions as the resulting material was only soluble in organic solvents. To avoid
this, a dendron box structure was developed based on the water-soluble
third-generation hydroxyl-terminated dendron, passivated with another
second-generation dendron resulting in an amine-terminated dendron box,
the stability of which was comparable to the box prepared by the RCM route.
The amine functional group allowed numerous coupling reactions to be
carried out (Figure 6.9), and investigations into the material

s biocompati-
bility were also undertaken. 242 Similarly, carboxylate-terminated dendrons

'