The partially fluorinated oxo-alkoxide tungsten(VI) complexes WO(OR)4 [4; R = C(CH3)2CF3, 5; R = C(CH3)(CF3)2] have been synthesized as precursors for chemical vapour deposition (CVD) of WOx nanocrystalline material. Complexes 4 and 5 were prepared by salt metathesis between sodium salts of the fluoroalkoxides and WOCl4. Crystallographic structure analysis allows comparison of the bonding in 4 and 5 as the fluorine content of the fluoroalkoxide ligands is varied. Screening of as a CVD precursor by mass spectrometry and thermogravimetric analysis was followed by deposition of WOx nanorods.

Metallized organic layer constructs have a wide range of technological applications. Electroless deposition is an attractive technique by which to deposit metal overlayers because it is inexpensive and can be performed at low temperatures, compatible with organic materials. Amine borane reducing agents are versatile and are capable of depositing metals, semiconductors, and even insulators. We have investigated the role of amine borane reducing agents in the electroless deposition of copper on -CH-, -OH-, and -COOH-terminated SAMs adsorbed on gold using time-of-flight secondary ion mass spectrometry, optical microscopy, and complementary MP2 calculations. Three reducing agents were studied: amine borane, dimethylamine borane, and trimethylamine borane. At pH >9, -COOH-terminated SAMs form copper-carboxylate complexes, which serve as nucleation sites for subsequent copper deposition. The rate of copper deposition is dependent on the strength of the B-N bond of the amine borane reducing agent. Similarly, if the terminal group is nonpolar such as a -CH functionality, then the rate of copper deposition is dependent on the amine borane B-N bond strength. However, in contrast to -COOH-terminated SAMs, copper deposition does not begin immediately. If the terminal group contains polar bonds, such as the C-OH bond of -OH-terminated SAMs, deposition is dominated by the interaction of the reducing agent with the terminal group rather than the relative bond strengths of the amine borane reducing agents.

Bacterial growth with short-chain aliphatic alkenes requires coenzyme M (CoM) (2-mercaptoethanesulfonic acid), which serves as the nucleophile for activation and conversion of epoxide products formed from alkene oxidation to central metabolites. In the present work the CoM analog 2-bromoethanesulfonate (BES) was shown to be a specific inhibitor of propylene-dependent growth of and epoxypropane metabolism by Xanthobacter autotrophicus strain Py2. BES (at low [millimolar] concentrations) completely prevented growth with propylene but had no effect on growth with acetone or n-propanol. Propylene consumption by cells was largely unaffected by the presence of BES, but epoxypropane accumulated in the medium in a time-dependent fashion with BES present. The addition of BES to cells resulted in time-dependent loss of epoxypropane degradation activity that was restored upon removal of BES and addition of CoM. Exposure of cells to BES resulted in a loss of epoxypropane-dependent CO 2 fixation activity that was restored only upon synthesis of new protein. Addition of BES to cell extracts resulted in an irreversible loss of epoxide carboxylase activity that was restored by addition of purified 2-ketopropyl-CoM carboxylase/oxidoreductase (2-KPCC), the terminal enzyme of epoxide carboxylation, but not by addition of epoxyalkane:CoM transferase or 2-hydroxypropyl-CoM dehydrogenase, the enzymes which catalyze the first two reactions of epoxide carboxylation. Comparative studies of the propylene-oxidizing actinomycete Rhodococcus rhodochrous strain B276 showed that BES is an inhibitor of propylene-dependent growth in this organism as well but is not an inhibitor of CoM-independent growth with propane. These results suggest that BES inhibits propylene-dependent growth and epoxide metabolism via irreversible inactivation of the key CO 2 -fixing enzyme 2-KPCC.

We demonstrate a fast, flexible, parallel, and highly controllable method by which to synthesize a variety of nanoscale and mesoscale structures. This method addresses one of the most significant challenges in nanoscience: the in situ parallel placement and synthesis of nano-objects over the mesoscale. The method is based on electroless nanowire deposition on micropatterned substrates (ENDOM). In ENDOM nanostructures are produced at the boundary between two unlike materials if two conditions are met: (a) deposition is kinetically preferred on one of the materials while (b) transport of reactants is favored on the other. In this study, copper structures were deposited on patterned -OH/-CH3-terminated alkanethiolate self-assembled monolayers (SAMs) by exploiting the different reaction rates of electroless deposition on these using the reducing agent dimethylamine borane (DMAB). We demonstrate production of nanowires (width < 100 nm), mesowires (100 nm < width < ∼3000 nm), nanorings, nanopores, and nanochannels. We show that a variety of experimental conditions can be employed, making this method compatible with many substrates. We have also studied the nucleation and growth kinetics of the ENDOM process. The width of the deposit grows exponentially with deposition time and can be modeled using classical nucleation theory. Although the deposit width increases, the height and grain size of the copper deposit is constant (to within experimental uncertainty) with deposition time. These observations indicate that the minimum deposit width is controlled by the nanoparticle dimensions and so can be controlled using the reaction conditions.

Upon reduction with sodium borohydride, diazonium tetrachloroaurate salts of triazine dendrons yield dendron-coated gold nanoparticles connected by a gold-carbon bond. These robust nanoparticles are stable in water and toluene solutions for longer than one year and present surface groups that can be reacted to change surface chemistry and manipulate solubility. Molecular modeling was used to provide insight on the hydration of the nanoparticles and their observed solubilties.

The iridescent wings of the Chalcopterix rutilans damselfly (Rambur) (Odonata, Polythoridae) are investigated with focused ion beam/scanning electron microscopy, transmission electron microscopy, and time-of-flight secondary ion mass spectrometry. The electron microscopy images reveal a natural photonic crystal as the source of the varying colors. The photonic crystal has a consistent number and thickness (∼195 nm) of the repeat units on the ventral side of the wing, which is consistent with the red color visible from the bottom side of the wing in all regions. The dorsal side of the wing shows strong color variations ranging from red to blue depending on the region. In the electron microscopy images, the dorsal side of the wing exhibits varied number and thicknesses of the repeat units. The repeat unit spacings for the red, yellow/green, and blue regions are approximately 195, 180, and 145 nm, respectively. Three-dimensional analysis of the natural photonic crystals by time-of-flight secondary ion mass spectrometry reveals that changes in the relative levels of Na, K, and eumelanin are responsible for the varying dielectric constant needed to generate the photonic crystal. The photonic crystal also appears to be assembled with a chemical tricomponent layer structure due to the enhancement of the CHN species at every other interface between the high/low dielectric constant layers.

X‐ray photoelectron spectroscopy is used to study a wide variety of material systems as a function of depth (“depth profiling”). Historically, Ar+ has been the primary ion of choice, but even at low kinetic energies, Ar+ ion beams can damage materials by creating, for example, nonstoichiometric oxides. Here, we show that the depth profiles of inorganic oxides can be greatly improved using Ar giant gas cluster beams. For NbOx thin films, we demonstrate that using Arx+ (x = 1000‐2500) gas cluster beams with kinetic energies per projectile atom from 5 to 20 eV, there is significantly less preferential oxygen sputtering than 500 eV Ar+ sputtering leading to improvements in the measured steady state O/Nb ratio. However, there is significant sputter‐induced sample roughness. Depending on the experimental conditions, the surface roughness is up to 20× that of the initial NbOx surface. In general, higher kinetic energies per rojectile atom (E/n) lead to higher sputter yields (Y/n) and less sputter‐induced roughness and consequently better quality depth profiles. We demonstrate that the best‐quality depth profiles are obtained by increasing the sample temperature; the chemical damage and the crater rms roughness is reduced. The best experimental conditions for depth profiling were found to be using a 20 keV Ar2500+ primary ion beam at a sample temperature of 44°C. At this temperature, there is no, or very little, reduction of the niobium oxide layer and the crater rms roughness is close to that of the original surface.

Electroless deposition (ELD) is widely used in industry to deposit metals because it is inexpensive and compatible with organic materials. The deposition rate and deposited film properties critically depend on the reducing agent, complexing agent, and bath pH and temperature as well as bath additives. We have investigated the role of ethanolamine additives in the ELD of copper using the reducing agent dimethylamine borane on -CH- and -OH-terminated self-assembled monolayers (SAMs) adsorbed on gold. Three additives were studied: ethanolamine (EOA), diethanolamine (DEOA), and triethanolamine (TEOA). Both the chemical identity and concentration of the ethanolamine significantly affect the deposition process. We show that the Cu deposition rate is faster on -CH-terminated surfaces than on -OH-terminated SAMs because of the stronger interaction of the ethanolamines with the hydroxyl terminal group. In contrast to physical vapor deposition and other ELD processes, Cu deposits atop methyl-terminated SAMs using TEOA. However, using EOA and DEOA, copper penetrates through -CH-terminated SAMs to the Au/S interface. For -OH-terminated SAMs, copper is observed to penetrate through the SAM for all ethanolamines investigated. The amount of copper penetration through the SAM to the Au/S interface increases with ethanolamine concentration. These effects are attributed to an adsorption-inhibition mechanism and differences in the chelation of Cu in the deposition bath.