Surface Functionalization Of Ruthenium Nanoparticles By Metal-Ligand Interfacial Bonds And Application In Catalysis

Metal and semiconductor nanoparticles have stimulated intensive basic and technological research because of their unique chemical and physical properties that differ vastly from those of bulk materials and molecular species.Such nanoscale particles show great potential as the novel functional structural elements in very diverse applications such as nanoelectronic devices,multifunctional catalysts,chemical sensors,data storage,biological labeling,and so forth.Of these,monolayer-protected nanoparticles represent a unique class of nanomaterials that may be exploited as nanoscale building blocks for the construction of advanced functional nanostructures.Because of the nanocomposite nature,the particle material properties can be readily manipulated not only by the metal cores but also by the organic protecting layers as well as the metal-ligand interfacial bonding interactions.In this field,whereas mercapto derivatives have been used extensively as the ligands of choice for nanoparticle surface passivation because of the strong affinity of thiol groups to transition metal surfaces,recently several studies have shown that transition-metal nanoparticles,such as Au,Pt,Ti,Ru,and Pd,may also be passivated by stable metals-carbon covalent bonds.In recent years,it has been found that metal nanoparticles may also be functionalized by stable metal-carbon?or metal-nitrogen?covalent bonds that include metal-carbene?M=C?,metal-acetylide?M-C??/metal-vinylidene?M=C=C?and metal-nitrene?M=N?.Because of the formation of d?-p?interactions between the transition-metal nanoparticles and terminal carbon moieties,the interfacial resistance at the metal-ligand interface is markedly reduced,leading to the emergence of unprecedented optical and electronic properties.The purpose of this thesis is to explore the influence of other types of ligands that have specific organic functional group on the interfacial properties of nanoparticles,and to study the effect of metal-nonmetal interface on the optimization performance of organic catalytic reaction.Therefore,this thesis mainly introduce the surface functionlization of transition metal ruthenium nanoparticles using nitrile,isonitrile,spacial and terminal alkynes ligands was introduced in this paper,and also exploit the effect of interface structure on optical,electronic and catalytic properties of ruthenium nanoparticles.The main contents are as follows:?1?Stable ruthenium nanoparticles were prepared by the self-assembly of nitrile molecules on the nanoparticle surface.¹H NMR and TGA measurements suggested an end-on configuration of the metal-ligand interfacial bonds,which are consistent with the results of FTIR measurements and ¹⁵N isotopic labeling of the nitrile moiety.XPS measurements indicated that there was an obvious charge transfer phenomenon on the interfaces.Such strong metal-ligand interfacial bonds allowed for effective intraparticle charge delocalization between the particle-bound functional moieties,as manifested in photoluminescence measurements.?2?Stable ruthenium nanoparticles were prepared by the self-assembly of isonitrile ligands onto“bare”ruthenium colloid surfaces forming Ru=C=N interfacial bonds.The structure of Ru=C=N were proved by the successful olefin metathesis reaction with vinyl derivatives,which suggests an end-on configuration of the isonitrile ligands on the Ru nanoparticle surface.And a series of measurements showed the conjugated Ru=C=N interfacial bonding linkage led to extensive intraparticle charge delocalization and hence strong conjugation between particle-bound organic functional moieties,as manifested by a red shift of the emission maximum and reduced lifetime of nanoparticle-bound pyrene as compared to results of the free monomers.?3?Ruthenium nanoparticles capped with terminal and internal alkyne ligands were prepared and the ruthenium-alkyne interfacial bonding was examined by a series of characterization.It was concluded that internal alkyne might take?² side-on configuration to Ru metal surfaces and form weak?-?covalent bonds on ruthenium nanoparticles surface,through which extensive charge delocalization occurs among the adsorbed internal alkyne molecules.Due to steric effects and electronic effects,the internal alkyne capped ruthenium nanoparticles actived to hydrogenation of vinly groups and showed high selective catalytic performance for styrene hydrogenation.