A R T I C L E S
Boisselier et al.
of Yamamoto’s phenylazomethine dendrimers whose rigidity
brings about new specific features for properties of phenyla-
zomethine-DENs in materials science.9
AuNPs using polyethyleneglycol-terminated dendrimers,17 be-
cause of their biocompatibility17 and the applications of AuNPs
in nanomedicine.18
It has recently been shown that dendrimers assembled by click
chemistry10 can coordinate and electrochemically recognize
various transition-metal cations,11 and that such palladodendritic
complexes can be reduced to DEPdNPs that have remarkable
catalytic properties.12 Such a strategy does not work in the same
way for an approach to arene-cored DEAuNPs,13 and the
investigation toward a rationalization of the syntheses toward
this goal is presented and generalized here. Besides encapsula-
tion, exodendrimer stabilization is also well-known,14 and this
alternative has also been searched with arene-cored dendrimers15
constructed using a Newkome-type 1 f 3 connectivity.16
Moreover, our goal was to stabilize and inter alia encapsulate
A major finding in this work is that Percec-type triethyleneg-
lycol (TEG) tethers19 are not only tolerated for the synthesis of
DEAuNPs and DSAuNPs but they are even required for this
purpose in this new arene-cored dendrimer series, and under
certain circumstances they allow the AuNP formation. The key
additional role of the intradendritic 1,2,3-triazole rings, formed
by “click” reaction, on the AuNP formation and stabilization is
also shown.
Results
The synthesis of two series of arene-cored, PEG terminated
dendrimers of three generations has been carried out. For both
series, the dendrimer syntheses start by CpFe+-induced nona-
allylation of mesitylene15 followed by photolytic decomplex-
ation20 and Newkome-type 1 f 3 connectivity.16 The first series
of dendrimers was synthesized using “click” chemistry (den-
drimers 4, 5 and 6, Scheme 1), and the other one using the
Williamson reaction (dendrimers 9, 10 and 11, Scheme 2) in
order to graft PEG dendrons at the periphery of the dendrimers.
The AuNPs are stabilized by these PEGylated dendrimers,
synthesized by “click” chemistry (4, 5 and 6), in methanol using
NaBH4 as the reductant. The PEG-terminated (dendronized)
dendrimers (4-6 and 9-11) also allowed the reduction of AuIII
to Au0 in water without the presence of an additional reductant.
The shape and the size of the AuNPs have been studied by
UV-vis spectroscopy and transmission electron microscopy
(TEM) and the kinetics of formation and size variations of the
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