Reactivity of gold nanoparticles towards N-heterocyclic carbenes

Rodríguez‐Castillo, María; Laurencin, Danielle; Tielens, Frederik; Lee, Arie van der; Clément, Sébastien; Guari, Yannick; Richeter, Sébastien

doi:10.1039/c3dt53579g

Cited by 84 publications

(97 citation statements)

References 41 publications

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“…For NHC @Au 90 Pd 10 , a new TEM sample was prepared from a three‐week old aqueous solution and the mean size did not change (Figure D). Consequently, no significant leaching of metal complexes took place because this would result in a decrease of the metal‐core size . After immobilization on TiO 2 , the NPs were homogenously distributed over the TiO 2 and the mean size was retained with only minor coalescence of single particles (Figure C).…”

Section: Resultsmentioning

confidence: 99%

N‐Heterocyclic Carbene‐Modified Au–Pd Alloy Nanoparticles and Their Application as Biomimetic and Heterogeneous Catalysts

Tegeder

Freitag

Chepiga

et al. 2018

Chemistry A European J

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The preparation of water‐soluble, N‐heterocyclic‐carbene‐stabilized Au–Pd alloy nanoparticles by a straightforward ligand exchange process is presented. Extensive analysis revealed excellent size retention and stability over years in water. The alloy nanoparticles were applied as biomimetic catalysts for aerobic oxidation of d‐glucose, for which monometallic Au and Pd nanoparticles showed no or negligible activity. The alloy nanoparticles were further applied as titania‐supported heterogeneous catalysts for the mild hydrogenation of nitroarenes and the semihydrogenation of 1,2‐diphenylacetylene with a solvent‐dependent selectivity switch between E‐ and Z‐stilbene.

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Section: Resultsmentioning

confidence: 99%

N‐Heterocyclic Carbene‐Modified Au–Pd Alloy Nanoparticles and Their Application as Biomimetic and Heterogeneous Catalysts

Tegeder

Freitag

Chepiga

et al. 2018

Chemistry A European J

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“…The 13 C chemical shifts were referenced to TMS at 0 ppm by using the 13 114,117 and even Au. 114,118 Furthermore, in the case of functionalized NDs, the 1 H → 13 C CPMAS sequence selectively enhances the signal of 13 C nuclei located near the surface since (i) the protons in NDs are essentially located at the surface 35,37 and (ii) the CP transfer is only effective up to a few angstroms and suffers from dipolar truncation. 119 In the framework of this study, we thus decided to look into how to best characterize phosphorylated NDs using 1 H → 13 C and 1 H → 31 P CPMAS experiments.…”

Section: ■ Experimental Detailsmentioning

confidence: 98%

NMR and EPR Characterization of Functionalized Nanodiamonds

Presti

Thankamony²,

Alauzun

et al. 2015

J. Phys. Chem. C

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We investigated the potential of solid-state NMR using magic angle spinning (MAS) with and without dynamic nuclear polarization (DNP) and electron paramagnetic resonance (EPR) for the characterization of functionalized nanodiamonds (NDs). We showed that conventional 1 H, 31 P, and 13 C solid-state NMR spectra allow differentiating in a straightforward way NDs from commercial sources and custom-made NDs bearing aromatic or aliphatic phosphonate moieties at their surface. Besides, the short nuclear relaxation times prove the close proximity between the endogenous paramagnetic centers of NDs and the grafted organic moieties. EPR spectra confirmed the presence of these paramagnetic centers in functionalized NDs, which are centered on dangling bonds as well as a few N 0 defects, corresponding to the substitution of carbon atoms by nitrogen ones. Hyperfine sublevel correlation spectroscopy indicates that the N 0 paramagnetic centers are mostly located in the disordered shell of NDs. Preliminary DNP-enhanced NMR experiments at 9.4 T and 100 K under MAS have shown a lack of significant DNP enhancement, which can be attributed to the short relaxation times of the unpaired electrons and the nuclei in NDs. When using exogenous polarizing agents, the endogenous unpaired electrons contribute to a leakage of polarization. Furthermore, low temperatures lead to a broadening of NMR signals. It therefore appears that conventional direct excitation remains the NMR method of choice for the characterization of functionalized NDs. ■ INTRODUCTIONNanodiamonds (NDs), that is, diamond particles with a diameter smaller than 100 nm, are receiving considerable attention due to their remarkable hardness and thermal conductivity, luminescence properties, chemical inertness, and biocompatibility. 1−6 For instance, they have been proposed as fillers to reinforce the mechanical properties of polymers and ceramics, 7,8 as catalyst supports for metal nanoparticles (NPs), 9 or as nanovectors for various drugs. 4,6,10 Depending on the preparation and purification methods used, the surface of NDs can be terminated by a variety of functional groups, including carboxylic groups, hydroxyls, ketones, and lactone moieties. 5,11−14 To attain the targeted properties, the surface of nanodiamonds most often needs to be functionalized, so that the interactions between the NPs and their environment are optimal. Several methods have been proposed to tune the surface properties of NDs by covalent grafting of organic moieties. 14−20To date, the characterization of NDs functionalized by organic fragments has involved a variety of methods, such as X-ray photoelectron, 21 UV, 22 and FTIR 16,20,23−26 spectroscopies. Solid-state NMR spectroscopy has been attempted, 27−29 but the use of this technique is still limited despite the high specific surface area of NDs (∼150−300 m 2 ·g −1 ), which should be favorable for detecting the surface functional groups. So far, solidstate NMR studies of NDs have mainly focused on the investigation of the core and surface structure of N...

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“…2c). 34 The band at 1486 cm −1 suggested the existence of CO 3 2− . 32,33 Bands at 869 and 1068 cm −1 belong to the deformation and symmetric stretching modes of CO, which were also observed for the hydroxylcarbonate Y 2 O 3 precursor.…”

Section: Resultsmentioning

confidence: 99%

Fluorescence and room temperature activity of Y₂O₃:(Eu³⁺,Au³⁺)/palygorskite nanocomposite

Yang

2015

Dalton Trans.

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The fluorescence and room temperature activity of a palygorskite supported Y2O3:(Eu(3+),Au(3+)) nanocomposite were investigated to design a fluorescence-indicated catalyst. The effects of Au(3+) doping on the structure and surface properties of the host material were systematically characterized. The fluorescence intensity of Y2O3:Eu(3+) was affected by Au(3+) doping, which was related to the crystallinity of Y2O3. Excess Au(3+) ions were segregated to the host surface and reduced to metallic Au. The local symmetry of Eu(3+) was reduced by Au(3+) doping, which benefited the energy transfer between Eu(3+) and Au(3+). Energy absorbed by Eu(3+) was transferred from Au(3+) to metallic Au, where electrons were produced. These electrons were absorbed by O2 to change into O2(-), which acted as the oxidant for ortho-dichlorobenzene (o-DCB). The variation of fluorescence intensity during the catalytic reaction was observed. The room temperature catalytic activity of the nanocomposite under UV irradiation was revealed. The as-synthesized nanocomposite might have potential applications in environmental fields.

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Reactivity of gold nanoparticles towards N-heterocyclic carbenes

Abstract: The reaction of gold nanoparticles with benzimididazol-2-ylidene ligands leads to the formation of well-defined bis-carbene gold(i) complexes, as shown by characterization techniques such as powder XRD and solid state NMR.

Cited by 84 publications

References 41 publications

N‐Heterocyclic Carbene‐Modified Au–Pd Alloy Nanoparticles and Their Application as Biomimetic and Heterogeneous Catalysts

N‐Heterocyclic Carbene‐Modified Au–Pd Alloy Nanoparticles and Their Application as Biomimetic and Heterogeneous Catalysts

NMR and EPR Characterization of Functionalized Nanodiamonds

Fluorescence and room temperature activity of Y₂O₃:(Eu³⁺,Au³⁺)/palygorskite nanocomposite

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Reactivity of gold nanoparticles towards N-heterocyclic carbenes

Abstract: The reaction of gold nanoparticles with benzimididazol-2-ylidene ligands leads to the formation of well-defined bis-carbene gold(i) complexes, as shown by characterization techniques such as powder XRD and solid state NMR.

Cited by 84 publications

References 41 publications

N‐Heterocyclic Carbene‐Modified Au–Pd Alloy Nanoparticles and Their Application as Biomimetic and Heterogeneous Catalysts

N‐Heterocyclic Carbene‐Modified Au–Pd Alloy Nanoparticles and Their Application as Biomimetic and Heterogeneous Catalysts

NMR and EPR Characterization of Functionalized Nanodiamonds

Fluorescence and room temperature activity of Y2O3:(Eu3+,Au3+)/palygorskite nanocomposite

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Product

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Fluorescence and room temperature activity of Y₂O₃:(Eu³⁺,Au³⁺)/palygorskite nanocomposite