Functionalization of Porous Silicon Surfaces by Solution-Phase Reactions with Alcohols and Grignard Reagents

1998 ◽  
Vol 536 ◽  
Author(s):  
N. Y. Kim ◽  
P. E. Laibinis
Keyword(s):  
Porous Silicon ◽  
Room Temperature ◽  
Organic Molecules ◽  
Solution Phase ◽  
Silicon Surfaces ◽  
Covalent Attachment ◽  
Grignard Reagents ◽  
X Ray ◽  
Reaction Proceeds ◽  
Support Evidence

AbstractThis paper describes the covalent attachment of various organic molecules to the hydrogenterminated surface of porous silicon using alcohols and Grignard reagents. With alcohols, the chemical reaction forms Si-O-C attachments to the silicon substrate and requires modest heating (40–70 °C). With Grignard reagents, the reaction proceeds at room temperature and forms a covalent film that is attached by Si-C bonds to the silicon support. Evidence for these reactions is provided by infrared and x-ray photoelectron spectroscopies.

Thermal Functionalization of Hydrogen-Terminated Porous Silicon Surfaces with Terminal Alkenes and Aldehydes

2000 ◽  
Vol 638 ◽  
Author(s):  
Rabah Boukherroub ◽  
David J. Lockwood ◽  
Danial D. M. Wayner ◽  
Leigh T. Canham
Keyword(s):  
Porous Silicon ◽  
Diffuse Reflectance ◽  
Organic Molecules ◽  
Silicon Surfaces ◽  
Organic Monolayers ◽  
Chemical Reagent ◽  
X Ray ◽  
Chemically Modified ◽  
Terminal Alkenes ◽  
Diffuse Reflectance Infrared

AbstractH-terminated porous silicon (PSi) surfaces were chemically modified with terminal alkenes and aldehydes at high temperature to yield organic monolayers covalently attached to the surface through Si-C and Si-O-C bonds, respectively. Diffuse reflectance infrared Fouriertransform and X-ray photoelectron spectroscopies have been used to characterize the surfaces. Derivatized surfaces retain the PSi photoluminescence. Chemography was used to monitor the chemical changes of the PSi surface when exposed to 100% humidity in air. Organic monolayers linked through Si-C bonds are found to be highly resistant and have shown a better protection of the surface against corrosion compared to surfaces that are linked through Si-O-C bonds. The surface functionalized with ethyl undecylenate exhibits an even higher passivation of the surface through the presence of small amounts of oxide, which are induced by traces of water present in this chemical reagent, along with organic molecules attached to the surface.

Effect of Au on the Performance of Porous Silicon/V2O5 Nanorods Heterojunctions to NO2 Gas

NANO ◽  
2016 ◽  
Vol 11 (07) ◽  
pp. 1650079 ◽  
Author(s):  
Wenjun Yan ◽  
Ming Hu ◽  
Jiran Liang ◽  
Dengfeng Wang ◽  
Yulong Wei ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Porous Silicon ◽  
Room Temperature ◽  
Au Nanoparticles ◽  
Analytical Techniques ◽  
Heating Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Electron

A novel composite of Au-functionalized porous silicon (PS)/V2O5 nanorods (PS/V2O5:Au) was prepared to detect NO2 gas. PS/V2O5 nanorods were synthesized by a heating process of pure vanadium film on PS, and then the obtained PS/V2O5 nanorods were functionalized with dispersed Au nanoparticles. Various analytical techniques, such as field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), have been employed to investigate the properties of PS/V2O5:Au. Herein, the PS/V2O5:Au sample exhibited improved NO2-sensing performances in response, stability and selectivity at room temperature (25[Formula: see text]C), compared with the pure PS/V2O5 nanorods. These phenomena were closely related to not only the dispersed Au nanoparticles acting as a catalyst but also the p-n heterojunctions between PS and V2O5 nanorods. Whereas, more Au nanoparticles suppressed the improvement of response to NO2 gas.

Synthesis of Nanophase Noble Metal Systems Utilizing Porous Silicon

1996 ◽  
Vol 457 ◽  
Author(s):  
I. Coulthard ◽  
T. K. Sham
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Porous Silicon ◽  
Noble Metal ◽  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
Visible Range ◽  
X Ray ◽  
Metallic Salt ◽  
Scanning Electron

ABSTRACTApart from its well known ability to luminesce very intensely at room temperature in the visible range, porous silicon is also an effective reducing agent. We report the formation of several noble metal (Pd, Ag, Au, Pt) nanostructures by reductive dispersion of metal ions from aqueous solutions onto the surface of porous silicon. The nanophase systems produced by reductive deposition vary with the element deposited and the metallic salt utilized in the process. The resulting nanophase systems were studied using a variety of techniques including: scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and spectroscopie methods using synchrotron radiation.

Comparison of room temperature photoluminescence decays in anodically oxidized crystalline and X-ray-amorphous porous silicon

1993 ◽  
Vol 57 (1-6) ◽  
pp. 105-109 ◽  
Author(s):  
E. Bustarret ◽  
I. Mihalcescu ◽  
M. Ligeon ◽  
R. Romestain ◽  
J.C. Vial ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Room Temperature ◽  
X Ray ◽  
Room Temperature Photoluminescence

Aliphatic Radical Relay Heck Reaction at Unactivated C(sp3)–H Sites of Alcohols

2018 ◽  
Author(s):  
Padon Chuentragool ◽  
Dongari Yadagiri ◽  
Taiki Morita ◽  
Sumon Sarkar ◽  
Marvin Parasram ◽  
...  
Keyword(s):  
Visible Light ◽  
Heck Reaction ◽  
Room Temperature ◽  
Halogen Atom ◽  
Organic Molecules ◽  
Alkyl Halides ◽  
Aliphatic Alcohols ◽  
Aliphatic Radical ◽  
Reaction Proceeds

<div>The Mizoroki−Heck reaction is one of the most efficient methods for alkenylation of</div><div>aryl, vinyl, and alkyl halides. Due to its innate nature, this protocol requires the employment of compounds possessing a halogen atom at the site of functionalization. However, the accessibility of organic molecules possessing a halogen atom at a particular site in aliphatic systems is extremely limited. Thus, a protocol that would allow a Heck reaction to occur at a specific non-functionalized C(sp3)−H site would be highly desirable.</div><div>Here, we report a radical relay Heck reaction which allows for a selective remote</div>alkenylation of aliphatic alcohols at unactivated β-, γ- and δ-C(sp3 20 )–H sites. The use of easily installable/removable Si-based auxiliary enables selective I-atom/radical translocation events at remote C−H sites followed by the Heck reaction. Notably, the reaction proceeds smoothly under mild visible light-mediated conditions at room temperature, producing highly modifiable and valuable alkenol products from readily available alcohols feedstocks. <br>

scholarly journals In situ metalation of free base phthalocyanine covalently bonded to silicon surfaces

2014 ◽  
Vol 5 ◽  
pp. 2222-2229 ◽  
Author(s):  
Fabio Lupo ◽  
Cristina Tudisco ◽  
Federico Bertani ◽  
Enrico Dalcanale ◽  
Guglielmo G Condorelli
Keyword(s):  
Porous Silicon ◽  
Photoelectron Spectroscopy ◽  
Relevant Information ◽  
Silicon Surfaces ◽  
Porous Si ◽  
Wet Chemistry ◽  
X Ray ◽  
Covalently Bonded ◽  
Phthalocyanine Ring

Free 4-undecenoxyphthalocyanine molecules were covalently bonded to Si(100) and porous silicon through thermic hydrosilylation of the terminal double bonds of the undecenyl chains. The success of the anchoring strategy on both surfaces was demonstrated by the combination of X-ray photoelectron spectroscopy with control experiments performed adopting the commercially available 2,3,9,10,16,17,23,24-octakis(octyloxy)-29H,31H-phthalocyanine, which is not suited for silicon anchoring. Moreover, the study of the shape of the XPS N 1s band gave relevant information on the interactions occurring between the anchored molecules and the substrates. The spectra suggest that the phthalocyanine ring interacts significantly with the flat Si surface, whilst ring–surface interactions are less relevant on porous Si. The surface-bonded molecules were then metalated in situ with Co by using wet chemistry. The efficiency of the metalation process was evaluated by XPS measurements and, in particular, on porous silicon, the complexation of cobalt was confirmed by the disappearance in the FTIR spectra of the band at 3290 cm−1 due to –NH stretches. Finally, XPS results revealed that the different surface–phthalocyanine interactions observed for flat and porous substrates affect the efficiency of the in situ metalation process.

Deposition of Photoluminescent Nanocrystalline Silicon Films by SiF4-SiH4-H2 Plasmas

1996 ◽  
Vol 452 ◽  
Author(s):  
G. Cicala ◽  
G. Bruno ◽  
P. Capezzuto ◽  
L. Schiavulli ◽  
V. Capozzi ◽  
...  
Keyword(s):  
Grain Size ◽  
Porous Silicon ◽  
Vapor Deposition ◽  
Room Temperature ◽  
Energy Gap ◽  
Chemical Vapor ◽  
Nanocrystalline Silicon ◽  
X Ray Diffraction ◽  
X Ray ◽  
Average Grain Size

AbstractVisible photoluminescence at 1.62 eV has been observed at room temperature from fluorinated and hydrogenated nanocrystalline silicon (nc-Si:H,F) produced in a typical plasma enhanced chemical vapor deposition system. The use of SiF4-SiH4-H2 mixture, because of the H2 dilution and the presence of SiF4, favours the amorphous - crystalline transition through the etching process of the amorphous phase. The x - ray diffraction measurements give an average grain size of about 100 Å. The presence of these nanocrystals shifts the absorption edge of the films towards higher energy. An energy gap of 2.12 eV is estimated, although the hydrogen content in the material is only 4.5 at. %. The temperature dependence of the photoluminescence behaves similarly to that of porous silicon.

Diastereoselective One-Pot Tandem Synthesis of Chromenopyridodiazepinones through 1,4- and 1,6-Aza-Conjugate Additions/Heterocyclizations

Synlett ◽  
2018 ◽  
Vol 29 (07) ◽  
pp. 885-889 ◽  
Author(s):  
Oualid Talhi ◽  
Artur Silva ◽  
Abdelghani Bouchama ◽  
Ridha Hassaine ◽  
Nadia Taibi ◽  
...  
Keyword(s):  
Room Temperature ◽  
Amino Group ◽  
Conjugate Additions ◽  
One Pot ◽  
X Ray ◽  
X Ray Crystallography ◽  
Mild Conditions ◽  
Reaction Proceeds ◽  
Tandem Process ◽  
Tandem Synthesis

We report an efficient one-pot synthesis of a novel series of chromenopyridodiazepinone polyheterocycles by a catalyst-free nucleo­philic addition of ethane-1,2-diamine to (E,E)-3-[3-(2-hydroxyphenyl)-3-oxoprop-1-en-1-yl]-2-styrylchromones at room temperature under mild conditions. The reaction proceeds by a tandem process involving 1,4- and 1,6-aza-conjugate additions of one amino group of ethane-1,2-diamine to the α,β-unsaturated (3-oxoprop-1-en-1-yl) and the α,β,γ,δ-diunsaturated (2-styrylchromone) carbonyl system of the precursor, followed by imine condensation of the remaining amino group to generate the chromenopyridodiazepinone polyheterocycle. All compounds were characterized by means of one- and two-dimensional NMR spectroscopy and single-crystal X-ray crystallography.

Intense RT Visible Photoluminescence from Anodized Amorphous and Nanocrystalline Silicon Films

1992 ◽  
Vol 283 ◽  
Author(s):  
E. Bustarret ◽  
J. C. Bruyere ◽  
F. Muller ◽  
M. Ligeon
Keyword(s):  
Porous Silicon ◽  
Room Temperature ◽  
Nanocrystalline Silicon ◽  
Current Debate ◽  
X Ray ◽  
Boron Doped ◽  
Intense Luminescence ◽  
Conductive Substrates ◽  
Uv Excitation ◽  
Room Temperature Luminescence

ABSTRACTHeavily Boron-doped micrometer-thick amorphous (a-Si:B:H) or nanocrystalline (nc-Si) silicon layers have been deposited on a variety of conductive substrates by the 50 KHz PECVD of SiH4 / B2H6 / H2 mixtures at 320°C. These films have been partially electro-oxidized in a HF solution and then anodically oxidized in water in a manner similar to that yielding luminescent porous monocrystalline silicon layers (PcSL). Although the anodized films are x-ray amorphous, they yield intense luminescence properties at room temperature very similar to those of anodically oxidized PcSL with a similar vibrational spectrum. In both anodically oxidized materials, aging is shown to improve the external quantum efficiency. In amorphous anodized layers, optical microscopy under UV excitation showed strongly luminescent strain-related heterogeneities (20 μ,m in diameter) connected by non luminescent channels. The incidence of our results on the current debate about the origin of visible room-temperature luminescence in porous silicon and Si:O:H systems is discussed.

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