Carbon nanoparticles were prepared by refluxing the combustion soot of natural gas in nitric acid. Transmission Electron Microscopy measurements showed that the resulting particles exhibited an average diameter of 4.8 ± 0.6 nm, and the crystalline lattices were consistent with graphitic carbons. 13C NMR and FTIR spectroscopic measurements further confirmed the presence of sp2 carbons in the form of aryl and carboxylic/carbonyl moieties. The resulting carbon nanoparticles were found to emit photoluminescence with a quantum yield of approximately 0.43%. Additionally, the emission band energy of the carbon nanoparticle was very similar to that of much smaller carbon nanoparticles obtained from candle soot, suggesting that the photoluminescence might arise from particle surface states, analogous to the behaviors of semiconductor quantum dots with an indirect bandgap. In electrochemical measurements, two pairs of well-defined voltammetric waves were observed, which might be ascribed to the peripheral functional moieties that were analogous to phenanthrenequinone derivatives. Interestingly, the carbon nanoparticles might also be exploited as nanoscale structural scaffolds for the deposition of nanostructures of varied transition metals, leading to the formation of metal−carbon functional nanocomposites.

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.

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Stable ruthenium nanoparticles were synthesized by protecting the particles with diazo molecules that reacted readily with the ruthenium surface forming RuC carbene bonds, as manifested in Fourier transform infrared and 1H NMR measurements. The resulting particles, with the core diameter averaged at 2.12 ± 0.72 nm as determined by transmission electron microscopic measurements, showed a Mie scattering profile in optical absorption measurements. In electrochemical studies, the particles exhibited interesting quantized charging characteristics, similar to those observed with alkanethiolate-protected gold (AuSR) nanoparticles. In addition, a proof-of-concept experiment was carried out to demonstrate that metathesis reactions on ruthenium surfaces might be exploited for the chemical functionalization of the particles through efficient surface place exchange reactions. 1H NMR spectroscopy was used to monitor the reaction kinetics which exhibited a rate constant twice that observed with AuSR particles with another thiol ligand.