Chemistry Reference
In-Depth Information
Fig. 11 High-resolution positive ion ESI-MS characterisation of Au clusters stabilised with the
indicated diphosphine ligand, L
n
, where L¼Ph
2
P-(CH
2
)
n
-PPh
2
:(a)L
3
(
n
¼ 3); (b)L
5
(
n
¼ 5);
(c)L
6
(
n
¼ 6). The inset in (a) shows the isotopic pattern of the [Au
11
(L
3
)
5
]
3+
peak and the
simulated isotopic pattern using the natural
isotopic abundances of Au, P, C and
H. Figure reproduced from [
149
]
2.4.3 Post-reduction Phase
Several studies have examined post-synthetic modification of gold nanoclusters
[
152
-
157
]. Konishi et al. [
58
] have used ESI-MS to show that the polydisperse
solution of gold nanoclusters formed upon reduction of the dinuclear complex
Au
2
(dppe)Cl
2
by NaBH
4
(Fig.
13a
) transforms of the monodisperse cluster
[Au
13
L
5
Cl
2
]
3+
after treatment with HCl for 3 h (Fig.
13b
).
ESI-MS is a valuable tool to monitor the reactions that occur after chemical
reduction [
142
], which is known to be complete within hours after the addition
sodium borohydride [
158
]. In Fig.
14
, the initial distribution of [Au
8
L
6
4
]
2+
remains
persistent over at least 6 days after the addition of sodium borohydride. After
14 days, a new peak corresponding to [Au
9
L
6
4
Cl]
2+
is observed.
