5 Covalent Assemblies of Metal Nanoparticles—Strategies …
157
of the esterification reaction. As expected, the increase in the molecular length of the
diacids results in larger inter-particle spacing (Fig. 5.21).
Ester coupling (Fig. 5.20b) of monolayer-protected Au NP (11mercaptoundecanoic acid exchanged and 11-mercaptoundecanol exchanged)
was performed with ester coupling reagents such as 1,3-dicyclohexylcarbodiimide
and 4-(dimethylamino) pyridine [120]. Bifunctionalized Au NP (1.1 nm) with
two octadentate thioether ligands were covalently interlinked [94]. Since two
ligands are required to cover the NP surface, exactly two triisopropylsilyl-protected
acetylenes are present as functional groups on the periphery of the NP, allowing
their interlinking by wet chemistry: (i) deprotection of the acetylene by fluoride
ions and (ii) rapid (15 min.) oxidative acetylene coupling (Fig. 5.20c). In these
Fig. 5.21 Assembly of Ag NP mediated by different dicarboxylic acids, and the resulting TEM
images, where the average inter-particle distances are indicated. Reproduced with permission from
Ref. [98]
157
of the esterification reaction. As expected, the increase in the molecular length of the
diacids results in larger inter-particle spacing (Fig. 5.21).
Ester coupling (Fig. 5.20b) of monolayer-protected Au NP (11mercaptoundecanoic acid exchanged and 11-mercaptoundecanol exchanged)
was performed with ester coupling reagents such as 1,3-dicyclohexylcarbodiimide
and 4-(dimethylamino) pyridine [120]. Bifunctionalized Au NP (1.1 nm) with
two octadentate thioether ligands were covalently interlinked [94]. Since two
ligands are required to cover the NP surface, exactly two triisopropylsilyl-protected
acetylenes are present as functional groups on the periphery of the NP, allowing
their interlinking by wet chemistry: (i) deprotection of the acetylene by fluoride
ions and (ii) rapid (15 min.) oxidative acetylene coupling (Fig. 5.20c). In these
Fig. 5.21 Assembly of Ag NP mediated by different dicarboxylic acids, and the resulting TEM
images, where the average inter-particle distances are indicated. Reproduced with permission from
Ref. [98]