Iodoarene-Catalyzed Cyclizations of Unsaturated Amides

The cyclization of N-alkenylamides catalyzed by iodoarenes under oxidative conditions is presented. Five-, six-, and seven-membered rings with a range of substitutions can be prepared by this route. Preliminary data from the use of chiral iodoarenes as precatalysts show that enantiocontrol is feasible

Laser treatment of Ag@ZnO nanorods as long-life-span SERS surfaces.

This is the accepted manuscript. The final version is available from ACS at http://pubs.acs.org/doi/abs/10.1021/am506622x.UV nanosecond laser pulses have been used to produce a unique surface nanostructuration of Ag@ZnO supported nanorods (NRs). The NRs were fabricated by plasma enhanced chemical vapor deposition (PECVD) at low temperature applying a silver layer as promoter. The irradiation of these structures with single nanosecond pulses of an ArF laser produces the melting and reshaping of the end of the NRs that aggregate in the form of bundles terminated by melted ZnO spherical particles. Well-defined silver nanoparticles (NPs), formed by phase separation at the surface of these melted ZnO particles, give rise to a broad plasmonic response consistent with their anisotropic shape. Surface enhanced Raman scattering (SERS) in the as-prepared Ag@ZnO NRs arrays was proved by using a Rhodamine 6G (Rh6G) chromophore as standard analyte. The surface modifications induced by laser treatment improve the stability of this system as SERS substrate while preserving its activity.We thank the Junta de Andalucía (TEP8067, FQM-6900 and P12-FQM-2265) and the Spanish Ministry of Economy and Competitiveness (Projects CONSOLIDER-CSD 2008-00023, MAT2011-28345-C02-02, MAT2013-40852-R, MAT2013-42900-P and RECUPERA 2020) for financial support. The authors also thank the European Union Seventh Framework Programme under Grant Agreements 312483-ESTEEM2 (Integrated Infrastructure Initiative-I3) and REGPOT-CT-2011-285895-Al-NANOFUNC, and the European Research Council under the European Union’s Seventh Framework Programme (FP/2007-2013)/ERC grant agreement 291522 - 3DIMAGE. R. J. Peláez acknowledges the grant JCI-2012_13034 from the Juan de la Cierva program

GAS PHASE REACTION IN SYNTHESIS OF SiC FILMS BY LOW PRESSURE CHEMICAL VAPOR DEPOSITION FROM Si2H6 AND C2H2 AT 873 K

Silicon carbide (SiC) films were synthesized by the low pressure chemical vapor deposition (LPCVD) method, using Si2H6 and C2H2 as reactant gases at 873 K in a horizontal tubular reactor. Kinetic studies using gas chromatography were used to understand the gas-phase and surface chemistry of Si2H6 in the presence of C2H2. The results showed that the direct reaction of Si2H6 on substrate surface was strongly retarded by C2H2 and that the film formation species was either SiH2 or a gas-phase intermediate derived from Si2H6 and C2H2, having a sticking probability of 0.1

THE REACTIVITY AND MOLECULAR SIZE OF FILM PRECURSORS DURING CHEMICAL VAPOR DEPOSITION OF WSix

A kinetic study of chemical vapor deposition of tungsten silicide films was made, focusing on the reactivity and molecular size of film precursors. Tungsten silicide (WSix) films were deposited by low pressure CVD from SiH4and WF6. The molecular size of the film precursor was calculated to fit to the diffusion coefficient obtained from the deposition rate profile in a tubular reactor. Typically the size was 5~6Å, which is close to the size of the WF6 molecule. The sticking probability of the film precursor was also examined by observing step coverage in a micron size trench. The sticking probability was about 0.5 at 270~360°C and dependent only slightly on temperature. The partial pressure ratio of SiH4 to WF6 was varied from 5 to 100, but the sticking probability did not change and the step coverage remained poor. Some modifications of reaction system would be required to improve the step coverage

Monte Carlo simulation on the step coverage formation processes in chemical vapor deposition

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