Papers by Keyword: Silylation

Abstract: We studied possibility of silylation of lithiated carbohydrates using chlorosilanes. We observed that after the lithiation, the silylation is concurrent with a protonation reaction. In the case of trimethyl chlorosilane, we achieved 1:1 ratio with 36% isolated yield, while triphenyl chlorosilane gave 1:2 (silylated:reduced) ratio and 4% isolated yield. In the case of benzyl protected carbohydrate, silylation at benzylic position was observed.

Abstract: Amphiphilic functionalized montmorillonite (MMT) has been employed in hydrophobic compounds delivery systems. In the present study, MMT intercalated by 3-aminopropyl trimethoxysilane (APS) was employed for the delivery of the model compounds of resveratrol (RSV). The structure and surface morphology of APS-MMT were characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, thermogravimetry, scanning electron microscopy, and contact angle analysis. The loading and release efficiencies of RSV were also investigated. Our study showed that the aminosilane-modified MMT is promising for use in poorly water-soluble compounds carrier systems owing to their natural and excellent performance.

Abstract: A rapid repair process of plasma damaged SiCOH in combination with post-etch residue removal has been developed. The carbon depletion layer caused by plasma dry etching was repaired by subsequent surface modifying SAM treatment, which resulted in replenishment of carbon not only on the surface but also a few nm toward the bulk. This repairing technique provides a high-quality hydrophobic surface under conditions of low temperature and short process time. In addition, the SAM layer can be expected to act as an adhesion promotor with metal materials.

Abstract: Porous ultra low constant materials (ULK) for isolation within the interconnect system of integrated circuits are a promising approach to reduce crosstalk and RC-delays due to shrinking feature sizes [1]. Due to their porosity and the integration of carbon rich species like methyl groups into the Si-O-Si backbone of currently fabricated PECVD SiCOH dielectrics those materials are highly sensible towards plasma processing, e.g. dry etching or resist stripping [2]. Metal hard mask approaches, e.g. using TiN hard masks are widely used to prevent the resist stripping plasma directly attacking the low-k material [3]. To reduce further plasma damage like carbon depletion and formation of polar silanol groups the development of less aggressive etching processes is in the focus of research and development activities. Nevertheless dry etching will attack the sidewalls and cause a material degradation. That is why repair processes, mainly based on silylation, are considered to follow the patterning step to reintegrate carbon rich species and to recover the dielectric’s properties [3]. Subsequently to dry etching and repairing the dielectric the wet chemical plasma etch residue removal process is performed. Besides material compatibility and effectiveness in residue removal the wetting behavior of the applied cleaning solutions towards the surface which has to be cleaned is crucial, especially looking on wetting issues like the incomplete wetting of very small via holes or pattern collapse. In this study we investigate in which way different silylation based repair processing regimes are affecting the wettability of the dielectric by water based cleaning solutions using contact angle based surface energy calculations.

Abstract: Four different synthetic methods for preparation of aromatic sialnes have been developed and the hydrosilylation route has been proved to be one as the most commercially significant. A series of specialty aryl silanes have been synthesized for the potential applications of high performance and high temperature as silane coupling agents. The thermal stabilities of the bridged aromatic silanes have been examined using thermal gravimetric analysis (TGA) and compared against the gamma-substituted alkylsilanes and phenyltrimethoxysilane. These materials have greater thermal stability than the gamma-substituted, but marginally lower than phenyltrimethoxysilane.

Abstract: A novel stem-loop structured fluorescent oligoDNA probe (molecular beacon probe) bearing a silylated pyrene derivative at C-5 position of deoxyuridine has been synthesized. The fluorescently labeled modified nucleoside has been incorporated into two consecutive positions in the stem segment of the DNA using an automated DNA synthesizer. The resulting modified DNA exhibited an excimer fluorescent signal upon binding to the fully matched complementary DNA strand. The excimer emission was, however, effectively quenched while it stays alone or it hybridizes to a single base mismatched complementary target.

Abstract: RH-MCM-41, a mesoporous molecular sieve, was successfully synthesized from silica extracted from rice husk. The presence of silanol functional group (Si-OH) on its surface causes adverse effects on the adsorption of some non-polar compounds, especially benzene, toluene, ethylbenzene and xylene (BTEX). Thus, this work aims to enhance the adsorbability of RH-MCM-41 on BTEX adsorption by in-situ and ex-situ silylation. Trimethylchlorosilane (TMCS) was used as a silylating reagent to reduce silanol groups. The ex-situ silylation was carried out by adding as-synthesized RH-MCM-41 into 5% v/v of TMCS solution at 30°C and stirring for 24 h. While the in-situ silylated sample was prepared by mixing 5% v/v of TMCS solution and RH-MCM-41 precursor solution at 80°C and stirring for 120 h. The adsorption capacity of gaseous BTEX using the silylated RH-MCM-41 was determined by gas chromatography equipped with a flame ionization detector (GC-FID) with a thermal desorption unit (TDU). The adsorption capacities of the ex-situ samples were 0.617 mg g^-1 for benzene, 1.271 mg g^-1 for toluene, 1.902 mg g^-1 for ethylbenzene and 0.036 mg g^-1 of xylene, higher than that of the in-situ and the unsilylated samples. Thus, the ex-situ silylation is suitable for enhancement of hydrophobicity of RH-MCM-41. The ex-situ silylated RH-MCM-41 has the potential to be applied in gaseous BTEX treatment.

Abstract: We have synthesized novel perylene derivatives bearing a silyl function with modifiable functional groups as a feasible material for visualizing biological substances. The fluorescent perylene derivative was coupled to C-5 position of pyrimidine nucleotide and the nucleotide was subsequently incorporated to the middle position of oligoDNA using an automated DNA synthesizer. Also, the derivative was coupled with a cholesterol analog with different length of linking alkyl function. The resulting modified fluorescent oligoDNA exhibited a small change in its fluorescent signal upon hybridization with the complementary oligoDNA. While the cholesterol analogs bearing the silylated perylene exhibited marked fluorescent signal in living cells. The signal is stronger in the analog having longer linker function compared to the analog having shorter linker function. In each case, however, the signal was much prominent compared to that of dehydroergosterol (DHE), a fluorescent cholesterol analog widely used in biological study.