5 Covalent Assemblies of Metal Nanoparticles—Strategies …
179
Fig. 5.34 a, b pH-switching photocatalytic mechanism of the dynamic covalent heteroassembly
of Au-CHO and TiO 2 -NH 2 NP; c photocatalytic decolorization of methylene blue (MB) curves of
the Au–TiO 2 complexed in basic conditions with different amounts of Au–CHO NP: (a) 0; (b) 20;
(c) 40; (d) 100; (e) 160; (f) 220 μL; (d) photocatalytic decolorization of the tri-stable system under
different pH conditions. Reproduced with permission from Ref. [202]
control of the electron-transfer efficiency between Au and TiO 2 NP (controlled by
the covalent dynamic assembly), and the accessibility of the catalytic active surface
(non-covalent self-assembly).
C 60 and C 60 adducts were used for the synthesis of assembled NP using a one-step
procedure [41, 80–82]. Ru NP assembled over Ru-fulleride spheres have demonstrated to be a highly selective catalyst for the reduction of nitrobenzene. Indeed, this
catalyst is able to hydrogenate the nitro group first, and subsequently the aromatic
ring, which is in contrast with other heterogeneous catalysts based on Ru over carbon
[80, 211]. Ru@C 60 provides electro-deficient Ru species, which could be responsible
for such a selective system. DFT calculations together with experimental results point
out that the reaction selectivity is mainly governed by surface hydride coverage onto
the Ru NP surface. The reactivity can also be modulated by the ligands present on
the surface (C 60 , amine, carbene or a polymer) [211]. Ru NP assemblies displaying a
short-range order were obtained with the use of a hexakis fullerene C 60 adduct [41].
The C 66 (COOH) 12 multitopic ligand bearing –COOH anchoring groups, robustly
coordinated to the Ru NP surfaces, the high symmetry of which giving the possibility
to create a 3-D assembly. Ru@C 66 (COOH) 12 assemblies were active in the hydrogenation of nitrobenzene, and TEM analysis performed after catalysis has shown
that the 3-D assembly is maintained. However, the lack of porosity of the assembly
179
Fig. 5.34 a, b pH-switching photocatalytic mechanism of the dynamic covalent heteroassembly
of Au-CHO and TiO 2 -NH 2 NP; c photocatalytic decolorization of methylene blue (MB) curves of
the Au–TiO 2 complexed in basic conditions with different amounts of Au–CHO NP: (a) 0; (b) 20;
(c) 40; (d) 100; (e) 160; (f) 220 μL; (d) photocatalytic decolorization of the tri-stable system under
different pH conditions. Reproduced with permission from Ref. [202]
control of the electron-transfer efficiency between Au and TiO 2 NP (controlled by
the covalent dynamic assembly), and the accessibility of the catalytic active surface
(non-covalent self-assembly).
C 60 and C 60 adducts were used for the synthesis of assembled NP using a one-step
procedure [41, 80–82]. Ru NP assembled over Ru-fulleride spheres have demonstrated to be a highly selective catalyst for the reduction of nitrobenzene. Indeed, this
catalyst is able to hydrogenate the nitro group first, and subsequently the aromatic
ring, which is in contrast with other heterogeneous catalysts based on Ru over carbon
[80, 211]. Ru@C 60 provides electro-deficient Ru species, which could be responsible
for such a selective system. DFT calculations together with experimental results point
out that the reaction selectivity is mainly governed by surface hydride coverage onto
the Ru NP surface. The reactivity can also be modulated by the ligands present on
the surface (C 60 , amine, carbene or a polymer) [211]. Ru NP assemblies displaying a
short-range order were obtained with the use of a hexakis fullerene C 60 adduct [41].
The C 66 (COOH) 12 multitopic ligand bearing –COOH anchoring groups, robustly
coordinated to the Ru NP surfaces, the high symmetry of which giving the possibility
to create a 3-D assembly. Ru@C 66 (COOH) 12 assemblies were active in the hydrogenation of nitrobenzene, and TEM analysis performed after catalysis has shown
that the 3-D assembly is maintained. However, the lack of porosity of the assembly