Chemistry Reference
In-Depth Information
Fig. 4 Proposed structures
for the gold(I)-thiolate
precursor showing (a)a
discrete tetrameric gold(I)-
thiolate and (b) a straight
chain gold(I)-thiolate
polymer
Fig. 5 MALDI-TOF-MS
of AuNPs using the DCTB
matrix operating at
threshold laser fluence.
Figure reproduced from
[
87
]
stoichiometries, which would otherwise indicate an open chain polymer structure
(Fig.
4b
).
2.3.2 Reduction Phase
Few reports have appeared on the use of MS to examine the evolution of thiolate-
protected gold nanoclusters during the reduction phase. A rare example probed the
size evolution to monodisperse Au
25
(SCH
2
CH
2
Ph)
18
using MALDI-TOF-MS
(Fig.
5
)[
87
]. At approximately 5 min after the addition of sodium borohydride to
a stirring solution of gold/phenylethanethiol (1:6) in THF, polydisperse ligand-
protected AuNPs with the gold cores of Au
25
,Au
38
,Au
44
,Au
68
and Au
102
are
observed. The Au
68
ligand-protected cluster seems to act as an intermediate during
the reduction phase, where its disappearance occurs between 1 and 6 h. The Au
102
ligand-protected cluster persists until at least 6 h.
