Alkyne-Protected Ruthenium Nanoparticles

Abstract

Stable ruthenium nanoparticles protected by 1-octynyl fragments were synthesized by a wet chemical method. Transmission electron microscopic measurements showed that the resulting particles exhibited an average core diameter of 2.55 ( 0.15 nm with well-defined Ru crystalline lattice fringes. Because of the formation of RusCt bonds, the CtC vibrational stretch was found in FTIR measurements to red-shift to 1936 cm -1 from 2119 cm -1 that was observed for monomeric 1-octyne. Interestingly, the nanoparticles underwent ligand exchange reactions with alkynyl lithium (e.g., 5-phenyl-1-pentynyl lithium) for further surface functionalization, as manifested in FTIR as well as 1 H and 13 C NMR measurements. Optically, whereas UV-vis absorption measurements exhibited only a featureless profile, the Ru nanoparticles displayed apparent photoluminescence with an emission peak at 428 nm, which was accounted for by intraparticle charge delocalization as a consequence of the strong RusCt bonds and the conducting Ru metal cores such that the particle bound CtC moieties behaved analogously to diacetylene derivatives. The impacts of the interfacial bonding interactions on intraparticle charge delocalization were further illustrated by Ru nanoparticles functionalized with a mixed monolayer of both octyne and ethynylferrocene ligands. At a ferrocene surface coverage of ca. 13%, electrochemical measurements depicted two pairs of voltammetric peaks with a potential spacing of 265 mV. A new NIR absorption band centered around 1687 nm also started to emerge with the addition of nitrosonium tetrafluoroborate (NOBF 4 ) as the oxidizing reagent and the peak intensity exhibited a volcanoshape dependence on the amount of NOBF 4 added. These observations strongly suggested that there existed effective intervalence charge transfer between the particle-bound ferrocene groups at mixed valence, analogous to the observation where the ferrocene moieties were bound onto the particle surface by Ruscarbene π bonds.

One-pot Synthesis of Octyne-Ruthenium on Carbon Nanoparticles

“…Additionally, it can be seen that the adsorption peaks became narrower and contributed to the small red shift after treatment on metal nanoparticles [22]. The well-defined excitation and emission peaks shown at 360 and 450 nm, respectively were corresponding to the previous studies of ruthenium nanoparticles passivated by 1-dodecyne [7] and 1-octyne [16]. The high intensity of photoluminescence observed with the C/Ru/Oct nanoparticles strongly suggests that intraparticle charge delocalization took place as a result of the strong Ru=C interfacial bonding interactions.…”

“…al. [16] which was 2-3 nm sized average. Herein, it was reasonable to conclude the successful production of our process.…”

Controlled metal nanostructures: Fertile ground for coordination chemists

“…[142]. Other values reported on single layer systems lead to an average footprint area of 0.214 nm 2 for a thiolate ligand on Au NPs [196] and 0.15nm 2 for an alkynyl one on Ru NPs [197]. Mercaptopropionic acid, a very small bidentate ligand often used as a linker between Au NPs (via its thiol end group) and biomolecules (via its carboxylic acid end group), displays a slightly higher packing density: a recent study indicates an average footprint area of 0.13nm 2 , nearly independent of the size of the Au NPs (from 5 to 100nm) [192 a A c c e p t e d M a n u s c r i p t 26 less densely packed on a MNP surface, form weaker interligand interactions, leave larger "interligand" spacing, which is of interest for catalytic applications as the surface is more accessible [198], [199].…”

“…Recently the formation of M-C bonds at the surface of NPs has also been shown to efficiently stabilize MNPs. For example, one can cite 1-coordination of alkynyl or aryl ligands at the surface of respectively Ru NPs [137] and…”

Understanding the Enhanced Catalytic Performance of Ultrafine Transition Metal Nanoparticles–Graphene Composites

“…Ru NPs supported on active carbon showed high catalytic activity in hydrogenation of lactic acid, arene and ketone, and hydrolysis of NaBH 4 . [56][57][58] Ru NPs embedded in ordered mesoporous carbon material also demonstrated a higher activity in FischerTropsch synthesis, 59 hydrogenation of glucose, 60 and partial hydrogenation of dinitrobenzene into nitroanilines, 58 Finely dispersed Ru NPs on rGO also show superior catalytic performance in hydrogenation of arenes and ketone as compared with those deposed on mesoporous carbon. [61][62] To address the superior catalytic performance of these finely dispersed Ru NPs and especially the Ru NPs deposited on rGO.…”