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To improve the thermal and mechanical properties of water-based acrylate adhesives, epoxy functional silane oligomer (EFS) was investigated as a crosslinking agent at different curing temperatures from 100 to 140[degrees]C. Water-based acrylate adhesives with different EFS concentrations (0.0-2.0 wt%) were prepared and characterized by Fourier transform infrared spectrometry (FT-IR), colloidal stability, water absorption, mechanical and thermal properties. The thermal and mechanical properties of samples were investigated by means of differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), tensile testing, Izod impact, and dynamic mechanical analysis. The amount of EFS had a significant influence on the crosslinking process and curing temperature. FT-IR and TGA analysis revealed successful crosslinking of EFS with the water-based acrylate adhesive at 100[degrees]C temperature. The use of EFS after different curing processes showed higher tensile strength and lower water absorption. Among the percentage of EPS studied, the use of 1.0 wt% presented the most promising results for the improvement thermal and mechanical properties. In addition, the results obtained in this study provide new insights into the use of EFS as a coupling agent of water-based acrylate adhesives for woodfiber composites, as well as in the particleboard panels industry. KEYWORDS crosslinking acrylate adhesive, formaldehyde-free, functional epoxy silane, mechanical properties, one-component adhesive, 1 | INTRODUCTION Over the last 20 years, the use of thermoset polymers with wood derivates (fibers, laminates, and plywoods) in the automotive sector and in furniture-frame applications has been [...]

Reaction of complex [(ArN)Mo(H)(Cl)([PMe.sub.3]).sub.3] (1) with [BPh.sub.3] and silane [H.sub.3]SiPh affords a new silyl complex [(ArN)Mo([SiH.sub.2]Ph)(Cl)([PMe.sub.3]).sub.2] (3) that catalyses facile H-H/Si-H exchange. EXSY experiments suggest that this exchange does not involve the classical pathways such as oxidative addition of hydrogen or silane to the complex or [sigma]-bond metathesis. It is suggested that the exchange may occur in an FLP cage comprised by the complex and the silane. Key words: hydrogen, silane, imido, molybdenum, EXSY. La reaction du complexe [(ArN)Mo(H)(Cl)([PMe.sub.3]).sub.3] (1) avec le [BPH.sub.3] et le silane [H.sub.3]SiPh permet d'obtenir un nouveau complexe silyle, le [(ArN)Mo([SiH.sub.2]Ph)(Cl)([PMe.sub.3]).sub.2] (3), qui catalyse en douceur l'echange H-H/Si-H. Des experiences EXSY laissent supposer que cet echange ne procederait pas par les voies classiques comme l'addition oxydante d'hydrogene ou de silane au complexe ou la metathese de la liaison [sigma]. Nous posons l'hypothese selon laquelle l'echange s'effectuerait dans une cage dite de <>(PLF) formee par le complexe et le silane. [Traduit par la Redaction] Mots-cles: hydrogene, silane, imido, molybdene, EXSY., Introduction Dihydrogen is the simplest and yet one of the most important molecules, being the integral part of industrial hydrogenation reactions. (1) Activation of its strong and nonpolar H-H bond [...]

In this report, we demonstrate that quartz nanopipettes modified with an imidazole-terminated silane respond to metal ions ([Co.sup.2+]) in solution. The response of nanopipettes is evaluated through examination of the ion current rectification ratio. When nanopipettes are cycled between solutions of different pH, adsorbed [Co.sup.2+] can be released from the nanopipette surface, to regenerate binding sites of the nanopipette. These results demonstrate that rectification-based sensing strategies for nanopore sensors can benefit from selection of recognition elements with intermediate binding affinities, such that reversible responses can be attained. 10.1021/ac102619j

High-pressure structures of disilane ([Si.sub.2][H.sub.6]) are investigated extensively by means of first-principles density functional theory and a random structure-searching method. Three metallic structures with P-1, Pm-3m, and C2/c symmetries are found, which are more stable than those of [XY.sub.3]-type candidates under high pressure. Enthalpy calculations suggest a remarkably wide decomposition (Si and [H.sub.2]) pressure range below 135 GPa, above which three metallic structures are stable. Perturbative linear-response calculations for Pm-3m disilane at 275 GPa show a large electron-phonon coupling parameter [lambda] of 1.397 and the resulting superconducting critical temperature beyond the order of [10.sup.2] K. metallization | new phase | solid disilane doi/ 10.1073/pnas.1005242107

Epoxy resin is widely used as an insulation material in many electrical apparatuses because of its excellent electrical and manufacture characteristics. It is usually mixed with filler to improve mechanical and thermal characteristics. In order to qualitatively clarify the effect of fillers on treeing phenomena, treeing tests were performed with epoxy specimens mixed with different kinds of fillers. The property of the interface is also clarified by the treatment of silica filler using silane coupling. Although tree initiation voltage decreased with introducing silica fillers, the fillers prevented the growth of the tree. The effect of filler shape was more significant on round-shape filler than on square-shape filler. Silane coupling treatment to the fillers did not bring a significant change in tree initiation voltage, however, brought a reduction in tree propagation. The change in tree propagation rate was explained by considering the field relaxation and energy dispersion due to branching at the filler-resin interface. Tree propagation along the interface between resin and a quartz plate was observed and analyzed in order to ensure the above explanation. Index Terms--Epoxy resin, filler, treeing, silane coupling treatment, release agent, adhesion property, moisture.

The effects of common solvents on alkyl chain conformafional order in a series of high-density C22 stationary phases with surface coverage ranging from 3.61 to 6.97 [micro]mol/[m.sup.2] are investigated by Raman spectroscopy. Conformational order is evaluated using the intensity ratio of the antisymmetric and symmetric v(C[H.sub.2]) modes as well as the frequencies at which these Raman bands are observed. Solvents studied include methanol-[d.sub.4], acetonitrile-[d.sub.3], water-[d.sub.2], toluene-[d.sub.8], chloroform-d, and benzene[d.sub.6]. Alkyl chain conformational order and, hence, solvation of the stationary phase, is dependent on the Gibbs free energy change for these molecules at infinite dilution in hexadecane (AGED), as well as stationary-phase properties (polymerization method and surface coverage). In general, polar solvents increase slightly the conformational order of these C22 stationary phases, while nonpolar solvents decrease conformational order. A comparison is made between C22 and C18 bonded-phase systems to further understand the role of alkyl chain length on solvent--stationary phase interactions. The change in alkyl chain conformational order induced by solvent is also compared to that induced by temperature, which provides insight into the effect of chromatographic conditions on stationary-phase shape selectivity, an important application of these materials.

Quantum chemical calculations were used for examining [S.sub.H]2 reaction between methyl radical and methylsilane. Findings reveal the favorable proceeding of the backside mechanism for the [S.sub.H]2 reaction in a wide range of C-Si-C angles.

There is a great interest in electronic transitions in hydrogen-rich materials under extreme conditions. It has been recently suggested that the group IVa hydrides such as methane (C[H.sub.4]), silane (Si[H.sub.4]), and germane (Ge[H.sub.4]) become metallic at far lower pressures than pure hydrogen at equivalent densities because the hydrogen is chemically compressed in group IVa hydride compounds. Here we report measurements of Raman and infrared spectra of silane under pressure. We find that [SiH.sub.4] undergoes three phase transitions before becoming opaque at 27-30 GPa. The vibrational spectra indicate the material transforms to a polymeric (framework) structure in this higher pressure range. Room-temperature infrared reflectivity data reveal that the material exhibits Drude-like metallic behavior above 60 GPa, indicating the onset of pressure-induced metallization. high pressure | hydrogen-rich materials

A comprehensive study of interaction potentials of the prototype silane dimer in terms of HF, MP2 and DFT methods is presented. The studies provide better understanding effects of the repulsion exponent, the binding energy, the equilibrium bond length, and the asymptotic behavior of the intermolecular potentials.

The mechanism of excess electron and hole localizations in radical ions of poly(dimethylsilane) (PDMS) is investigated by means of molecular dynamics (MD) and extended Huckel methods. The geometry of PDMS with a regular all-trans form is fully optimized and the localization of the electron and hole is found after thermal activation.

The synthesis secondary amines, tertiary amines, and silyl enamines in the hydrosilane reduction of secondary amides catalyzed by a triruthenium complex is described.

A facile and efficient method is described for the cleavage of the Ar-Si bond of various aryl trimethyl silanes. These arylsilanes have readily undergone a solvent-free protodesilylation to the corresponding arenes at room temperature, when adsorbed on montmorillonite KSF (mont KSF).

Mechanistic studies have shown that the Lewis acid-promoted allylic rearrangement of [alpha]-silyloxy allylic silanes have proceeded along an ionic reaction pathway involving a contact ion pair. It is shown that the alleviation of steric congestion at the allylic position of the [alpha]-silyloxy allylic silane and stabilization of [[pi].cc] by hyperconjugation is the driving force behind this transformation.

New conditions are described for the preparation of trimethylsilyl-protected 2,2,2-trichloromethylcarbonols from aldehydes and ketones. A one-pot procedure, which avoids the use of strong bases, is described that has given access to 2,2,2-trichloromethylcarbinols.

The Si-C bond breakings in tetramethylsilane (TMS) when interacting with H/[H.sub.2] and the successive H abstractions from Si[H.sub.4]/C[H.sub.4] in the gas mixture of [H.sub.2]/C[H.sub.4]/TMS were explored. The results indicated that the Si-C bond breaking in TMS was caused by H radical.

The influence of the chemical structure of a triethoxysilane (TES), octadecyltriethoxysilane (ODTES), and ODTES/bistriethoxysilylpropyltetrasulfane (TESPT) mixture is investigated using inverse gas chromatography (IGC) at infinite dilution. Thermodynamic results indicate a higher polarity of the silica surface modified with TES as compared to that of the unmodified silica due to new OH groups deriving from the hydrolysis of ethoxy groups of the silane.

The creation and properties of colloidally stable shell-cross-linked cylindrical organometallic block copolymer micelles with adjustable length and swellability is reported. The findings showed that shell cross-linking is a prerequisite for generating ceramic replicas through the pyrolysis of polyisoprene-b-polyferrocenylsilane aggregates.

In this study a nano-electrospray emitter is constructed by precisely positioning entrapped octadecylsilane (ODS) particles within a photoinitiated polymer at the exit aperture of a capillary. Following poly-merization, the microsphere/polymer hybrid material is able to withstand pressures greater than 4000 psi for 1 cm length of material. Smaller microspheres (3 [micro]m) patterned at the exit aperture of a capillary generated the most sensitive/ stable electrospray from 100 to 1000 nL/min and moderately stable signal under 100 nL/min. Constant infusion of a standard PPG solution from a batch of eleven emitters resulted in a relatively small variance in total ion current (TIC) counts (8%). The entrapped microsphere emitter design yields an emitter that minimizes clogging and eliminates dead volume between the chromatographic bed and the electrospray emitter. The entrapped ODS microspheres can also be used for sample preparation prior to mass spectrometry (MS) analysis. We show the solid-phase extraction and preconcentration of 20-700 fmol of a peptide (leucine enkephalin) prior to MS analysis on an emitter with 1 cm of entrapped microspheres.

A combination of various techniques, including elemental analysis and BET analysis is used to study the use of p-toluenesulfonic acid for the controlled grafting of alkoxysilanes onto silanol containing surfaces. The described method has proved to be extremely useful, as it can be easily employed for the preparation of unable hydrophilic, hydrophobic, as well as super-hydrophobic silica.

The stereocontrolled synthesis of vinyl iodide along two alternative routes is described. The first route has used a standard Roush crotylation protocol, whereas the second method followed an allenyl silane propargylation with unexpected stereochemical consequences.

The thermal [C.sup.2]-[C.sup.6] cyclization of the enyne-allenes and their ring-closed and ring-opened products is described using an ultrafast radical clock. The results have provided a direct evidence for a stepwise mechanism in the [C.sup.2]-[C.sup.6] cyclization of enyne-allenes.

Matrix isolation infrared spectroscopy is used to study the conformations of dimethoxydimethylsilane (DMDMS) by trapping the silane in argon and nitrogen matrixes. Natural bond analysis has indicated that the charge-transfer hyperconjugative interactions have determined the conformational preferences in the molecule.

A study was conducted to study the reaction paths of 73 reactions with well-defined transition states that take place during and after the decomposition of methyltrichlorosilane (MTS). The studies provided insight into reaction pathways, Gibbs free energy barriers and thermodynamic properties of the transition states.

A study was conducted to determine the structures and energies of the gas-phase species generated during and after the various unimolecular decomposition reactions of methyltrichlorosilane (MTS). The studies provided insight into reaction enthalpies, heat capacity and entropies, and Gibbs free energies of various species.

A combination of Brook rearrangement-mediated [3+4] annulation and epoxysilane rearrangement have provided a new methodology for the construction of seven- and eight-membered carbocycles. The chirality transfer of epoxide to the remote positions via formal chiral carbanions through a tandem sequence has provided new aspects of asymmetric synthesis.

The effects of the structure of an alkoxysilane on the early reaction kinetics of sol-gel polymerization are examined in basic and acidic conditions. A high electron density at silicon leads to a low reactivity in basic condition but a high reactivity in acidic conditions and only bis(trimethoxysilylpropyl)amine (BTMSPA) in basic conditions defies these trends, possibly due to the effects of solvation near the reactive silicon site.

Monolithic silica capillary columns for HPLC were prepared from tetramethoxysilane to have smaller sized domains and increased phase ratios as compared to previous materials, and their performance was evaluated. The monolithic silica columns possessed an external porosity of 0.65-0.76 and a total porosity of 0.92-0.95 and showed considerably higher performance and greater retention factors in a reversed-phase mode after chemical modification than columns previously reported. An octadecyisilylated monolithic silica column with the smallest domain size (through-pores of ~1.3 [micro]m and silica skeletons of ~0.9 [micro]m) showed a plate height of less than 5 [micro]m at optimum linear velocities (u) of 2-3 mm/s in 80% acetonitrile for a solute having retention factors of ~1, and ~7 [micro]m at u = 8 mm/s. With a permeability similar to that of a column packed with 5-[micro]m particles, the monolithic silica columns were able to attain column efficiencies comparable to that of particulate columns packed with 2-2.5-[micro]m particles, and showed performance in the 'forbidden region' for the previous columns. The performance of the monolithic column can be compared favorably with that of a particle-packed column when 15 000-30 000 or more theoretical plates are desired at a pressure drop of 20-40 MPa or lower. The increased homogeneity of the co-continuous structures, in addition to the small-sized domains, contributed to the higher performance as compared to previous monolithic silica columns.

The syntheses and characterization of two new push-pull type second-order nonlinear optical (NLO) active isophorone-based alkoxysilane dyes with the same acceptor is reported. Normalized UV-vis spectra demonstrate that the introduction of a diaryl group would help to prevent unfavorable organization of the chromophores.

A procedure for the automated determination of isotopic abundances of silicon from biogenic and lithogenic particulate matter and from dissolved silicon in fresh or saltwaters is reported. Samples are purified using proven procedures through the reaction of Si with acidified ammonium molybdate, followed by precipitation with triethylamine and combustion of the precipitate to yield silicon dioxide. The silicon dioxide is converted to cesium hexafluosilicate by dissolution in hydrogen fluoride and the addition of cesium chloride. Isotopic analysis is accomplished by decomposing the cesium hexafluosilicate with concentrated sulfuric acid to generate silicon tetrafluoride gas. Silicon tetrafluoride is purified cryogenically and analyzed on a gas source isotope ratio mass spectrometer. Yields of silicon tetrafluoride are > 99.5%. The procedure can be automated by modifying commercial inlet systems designed for carbonate analysis. The procedure is free of memory effects and isotopic biases. Reproducibility is [+ or -] 0.03-0.10 [per thousand] for a variety of natural and synthetic materials.

Raman spectroscopy is used to investigate the effects of temperature, surface coverage, polymerization method (surface or solution polymerized), and nature of the alkylsilane precursor on alkyl chain conformational order in a series of high-density docosylsilane ([C.sub.22]) stationary phases at surface coverages ranging from 3.61 to 6.97 [micro]mol/[m.sup.2]. The results of this study contribute to an enhanced understanding of the shape-selective retention characteristics of these phases at a molecular level. Conformational order is evaluated using the intensity ratio of the antisymmetric and symmetric v(C[H.sub.2]) modes as well as the frequency at which these modes are observed. Alkyl chain order is shown to be dependent on surface coverage, alkyl chain length, and polymerization method. In general, alkyl chain order increases with surface coverage. Temperature-induced changes are observed between 250 and 350 K for the three phases with surface coverages between 3.61 and 4.89 [micro]mol/[m.sup.2]. These changes occur over a broad range of temperatures characteristic of two-dimensional systems, but in general adhere to the behavior predicted for a simple first-order transition. This change is not believed to be an abrupt cooperative disassociation characteristic of a phase transition in a bulk phase, but instead is thought to involve significant changes in conformational order in segments of the surface-tethered molecules, mostly those segments at the outer edge of the alkylsilane. In contrast to the changes observed in coverages below 5 [micro]mol/[m.sup.2], a first-order change is not observed for the stationary phase with coverage of 6.97 [micro]mol/[m.sup.2]. A molecular picture of the temperature-induced disorder is proposed with disorder originating at the distal carbon and propagating only a short distance toward the proximal carbon. A comparison is made between these [C.sub.22] stationary phases and similar high-density octadecylsilane ([C.sub.18]) bonded phases.

A novel technique is presented to disperse pristine single-walled carbon nanotubes (SWNTs) in water by ultrasonication in the presence of a thiolated organosilane and subsequent ultracentrifugation. The results have shown that these dispersed SWNTs would be an excellent scaffold for the realization of supramolecular nanoassemblies useful for a variety of applications ranging from nanoelectronics to drug delivery systems.

Thin poly(ethylene glycol) silane (PEG-silane) coatings formed from N-(triethoxysilyl propyl)-O-poly(ethylene oxide) urethane with different chain lengths of poly(ethylene glycol) (MW 750 and 4000-5000) are used to modify glass microfluidic channels and fused-silica capillaries for electrophoretic separations of proteins. These coatings combine three important properties, which make them favorable for proteomic analyses including reduction of protein adsorption, compatibility with mass spectrometry due to their stability, and the ability to control the magnitude of electroosmotic flow (EOF). The coatings have been successfully used in microfluidic chips and fused-silica capillaries for separation of protein sample mixtures under low EOF conditions. The long-chain and mixed PEG-silane coatings suppress electroosmotic flow by more than 90%, whereas the short-chain PEG silane suppresses EOF by 65-75% at pH values of 3-9. The long-chain and mixed PEG-silane coatings are suitable for low EOF applications or for cases where negative effects of EOF are to be minimized. Efficient separations of unlabeled basic proteins at low pH and FITC-labeled proteins at high pH were achieved, as well as excellent stability for at least 200 electrophoretic runs. Additionally, these covalent coatings produce no detectable background ions in ESI-MS, making them compatible with on-line mass spectrometry.

A concise alternative approach is reported for the synthesis of a range of aryl-substituted cyclohexenediols and cyclohexanetetraols involving the reductive radical arylation of benzene and subsequent treatment with osmium tetroxide. The method is conceptually related to the work of Landais on the desymmetrization of cyclohexadienysilanes generated by Birch reduction or arylsilanes.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.solener.2005.10.009 Byline: J. Mullerova (a), S. JureAka (a), P. A utta (b) Keywords: Polycrystalline; Si:H; Dilution Abstract: We report on the results of the investigation of optical properties and structure of PECVD deposited thin films of hydrogenated polysilicon determined by UV-Vis and IR spectroscopy. The influence of the hydrogen dilution of silane plasma at the PEVCD deposition on the film properties was investigated. The refractive index, the optical band gap energy and the microstructure of hydrogen and oxygen were analysed. The changes are discussed and correlated with the structure, the changes of the surface morphology and the hydrogen to silicon bonding. The optical band gap becomes larger than that of the undiluted sample. The results show that at dilution between 20 and 30 the transition between amorphous and crystalline phase occurs and the sample becomes a mixture of amorphous, polycrystalline phase with nano-sized grains and voids with decreasing hydrogen concentration. The presence of interstitial oxygen and oxygen bonded in surface Si-OH groups was detected. Author Affiliation: (a) Department of Engineering Fundamentals, Faculty of Electrical Engineering, University of A1/2ilina, 031 01 LiptovskA1/2 MikulaA , Slovakia (b) University of West Bohemia, New Technologies -- Research Centre, Univerzitni 8, 306 14 PlzeA, Czech Republic Article History: Received 16 June 2005; Accepted 18 October 2005 Article Note: (miscellaneous) Communicated by: Associate Editor Arturo Morales-Acevedo

Time-resolved kinetic studies of the reaction of silylene, Si[H.sub.2], generated by laser flash photolysis of both silacyclopent-3-ene and phenylsilane are carried out to obtain second-order rate constants for its reaction with C[H.sub.3]Cl. The reaction was studied in the gas phase at six temperatures.

Disilanes react with the C[B.sub.11][Me.sub.11] radical (2) by methyl transfer from boron to silicon and forma highly reactive intermediate, stable below -60 degree Celsius for which is proposed the structure of internally charge-compensated boronium ylide (3). Attempted preparation of [Me.sub.3][C.sup.+]C[B.sub.11][Me.sub.12.sup.-] by halide metathesis results in products also consistent with the formation of boronium ylides.

The inhibitory effects of quaternary ammonium silane (QAS) and Biocidal ZF coatings are evaluated against the development of a mixed fungal and bacterial biofilm on silicone rubber tracheoesophageal shunt prostheses in vitro. New strategies are developed for the prevention of microbial colonization of silicone rubber voice prostheses.

The syntheses and crystal structures of zirconium and titanium complexes containing the chelating trisilane-1,3-diolate ligand [Me2Si(R2SiO)2](super 2-) (R = SiMe3) -H2 are reported. The chloride complexes [Me2Si(R2SiO)2]TiCl2 and [Me2Si(R2SiO)2]ZrCl2.2THF are prepared by the reaction of MCI4 (M = Ti, Zr) with [Me2Si(R2-SiO)2]2Ti and [Me2Si(R2SiO)2]2Zr.

The formation of dihydrogen trioxide (HOOOH) is reported as indeed the characteristic feature of the decomposition of various silyl as well as germyl hydrotrioxides, generated by the low-temperature ozonation of the corresponding silanes and germanes. Results of the detailed experimental and theoretical studies of the NMR and IR spectral characterization of the polyoxides under investigation as well as of the mechanism of their formation and decomposition are presented.

A description is provided about the convergent synthesis of three generations of carbosilane dendrimeric carbodiimides. A study was conducted on the extent of site isolation effect of the dendrimers with dilution experiments monitored by FT-IR spectroscopy on the corresponding dendrimeric ureas.

The development of an effective asymmetric metallophosphite-catalyzed intermolecular addition of acyl silanes to alpha,beta-unsaturated amides that can be achieved under mild reaction conditions in good yield and enantioselectivity is detailed. Through a cross over experiment, the silicon migration step in the reaction mechanism is shown to be strictly intramolecular.

The feasibility of Si-Si bond formation directly on the surface is investigated to contrast with the Si-C and Si-O bond forming reactions. It is found that coupling of a molecular silane and a hydride-terminated silicon surface can be mediated by zirconocence complexes, aromatic silanes show higher incorporation than aliphatic silane.

Sulfide radical cations can undergo a fragmentation process involving the cleavage of a bond beta to the positive charge like most radical cations. This reaction, in general, has interesting implications concerning the structural effects upon the fragmentation rate and mechanism and moreover, it leads to carbon radicals and can also have practical applications.

Hydrolysis and condensation of simple trifluorosilanes, HSiF(sub 3) and MeSiF(sub 3), is studied by quantum mechanical methods. The results suggest that the activation energy for hydrolysis by a water dimer is significantly lower than that for hydrolysis by a water monomer.

The photochemical reaction mechanisms of 1,3-silyl migration of allylsilane are investigated using a complete active space comprised of six electrons in six orbitals with the standard 6-31G(d) basis set. It is concluded that the stereochemistry in the photochemical 1,3-silyl migration of allylsilane has a retention preference.

Parent radical cation of nonpolar solvent (alkanes and alkyl chlorides) ionize 9-(trimethylsilyl)xanthenes and 9-(trimethylsilyl)fluorenes in a diffusion-controlled electron transfer. A mobility restriction of the benzylic silane group in positions vertical to the phenyl plane stabilizes the radical cation and accounts for a dissociative radical cations, which undergo C-Si bond fragmentation in the order benzylsilane > xanthenylsilane > fluorenylsilane.

Epoxyallylsilanes containing the bulky tert-butyldiphenylsilyl group undergo, upon treatment with Lewis acid, a sequential rearrangement-cyclization process, which leads stereoselectively to allyl- and vinylsilane functionalized cyclohexanol derivatives. The cyclization follows an ene mechanism, leading to the formation of either allyl-or vinylsilanes depending upon the structure of the starting epoxyallylsilane.

The consequences of double diastereodifferentiation in chiral Lewis base catalyzed aldol additions using chiral enoxysilanes derived from lactate, 3-hydroxyisobutyrate, and 3-hydroxybutyrate was investigated. Trichlorosilyl enolates derived from the chiral methyl and ethyl ketones were subject to aldolization in the presence of phosphoramides, and the intrinsic selectivity of these enolates and the external stereoinduction from chiral catalyst was studied.

The structure of aklylsilane self-assembled monolayers (SAM) on a rough aluminum surface is studied by atomic force microscopy (AFM). AFM studies with different chain lengths shows high friction of disordered short-chain SAMs whereas the heat treatment provides a mechanism for introducing disorder into a SAM.

In an effort to elucidate the molecular-level structural features that control shape-selective separations, we have investigated the molecular dynamics of chromatographic models that represent both monomeric and polymeric stationary phases with alkylsilane length and temperature conditions analogous to actual materials of low to high shape selectivity. The structural characterization of these models is consistent with previous experimental observations of alkyl chain order and disorder: alkyl chain order increases both with alkyl chain length and with reduced temperature. Models that represent shape-selective reversed-phase liquid chromatography (RPLC) phases possess a significant region of distal end chain order with primarily trans dihedral angle conformations; the extension of these ordered regions into the phase increases with an increase in chain length. Models with extended chain length ([C.sub.30]) possess a higher degree of conformational order and are relatively insensitive to changes in surface coverage, bonding chemistry, and temperature. Chromatography models of various chain lengths and over a temperature range that represents highly shape-selective RPLC stationary phases all contain a series of well-defined and rigid cavities; the size and depth of these 'slots' increase for the [C.sub.30] models, which may promote the enhanced separations of larger size shape-constrained solutes, such as carotenoids.