Edwin A. Baquero

Highly Stable Water‐Soluble Platinum Nanoparticles Stabilized by Hydrophilic N‐Heterocyclic Carbenes

Controlling the synthesis of stable metal nanoparticles in water is a current challenge in nanochemistry. The strategy presented herein uses sulfonated N-heterocyclic carbene (NHC) ligands to stabilize platinum nanoparticles (PtNPs) in water, under air, for an indefinite time period. The particles were prepared by thermal decomposition of a preformed molecular Pt complex containing the NHC ligand and were then purified by dialysis and characterized by TEM, high-resolution TEM, and spectroscopic techniques. Solid-state NMR studies showed coordination of the carbene ligands to the nanoparticle surface and allowed the determination of a (13)C-(195)Pt coupling constant for the first time in a nanosystem (940 Hz). Additionally, in one case a novel structure was formed in which platinum(II) NHC complexes form a second coordination sphere around the nanoparticle.

Synthesis and behavior of novel sulfonated water-soluble N-heterocyclic carbene (η4-diene) platinum(0) complexes

A series of water-soluble (NHC)Pt(0)(dvtms) and (NHC)Pt(0)(AE) complexes containing different sulfonated NHC ligands (dvtms = divinyltetramethyldisiloxane and AE = diallyl ether) are reported. The dvtms compounds have been found to be quite robust and to display some conformational rigidity, whereas their AE counterparts are less stable and more flexible. The catalytic evaluation of these complexes in the hydrosilylation of alkynes in water revealed no benefits in favor of the complexes containing the more labile spectator diene (AE), and a fairly regular catalytic behavior for all complexes that restricts the location of the sulfonate group to the proximity of the metal site.

1-Phenylisoquinoline larvicidal activity against Culex quinquefasciatus

The larvicidal potential of several dopamine 1-phenylisoquinoline derivatives against Culex quinquefasciatus third instar larvae was investigated in a rational search for insecticides. The results showed that these isoquinolines presented moderate larvicidal activity, that the presence of a substituent is needed on carbon 1 for such activity to be presented and that it may be possible to develop novel insecticidal compounds having potential use in controlling insects by appropriate structural modification of 1-phenylisoquinolines. This article presents a possible structure–larvicidal activity relationship for isoquinolinic compounds.

Surface-Engineering of Ultrathin Gold Nanowires: Tailored Self-Assembly and Enhanced Stability

Gold nanowires with a mean diameter of 1.7 nm were synthesized by reduction of HAuCl4 in a solution of oleylamine (OY) in hexane. A bilayer of oleylammonium chloride/oleylamine at the surface of the raw nanowires was evidenced by NMR and diffusion ordered spectroscopy (DOSY) experiments. After washing a monolayer of oleylammonium chloride remained at the surface of the nanowires. The oleylammonium chloride layer could be progressively replaced by a phosphine shell as evidenced with NMR and DOSY experiments, which are in good agreement with the adsorption energies given by density functional theory calculations. The nanowires crystallize into hexagonal superlattices with a lattice parameter that can be tailored depending on the ligand shell. Small-angle X-ray scattering showed the following lattice parameters: Au@OY+Cl-(OY) (a = 7.2 nm) > Au@TOPO/OY (a = 6.6 nm) > Au@ OY+Cl- (a = 4.1 nm) > Au@TOP (a = 3.75 nm). This is one of a few examples of surface modification of ultrathin nanowires that does not alter their morphology. Moreover, the nanowires coated with phosphines exhibited long time stability (at the opposite of other ligands like thiols) opening the way to more complex functionalization.