Oligomeric silsesquioxanes, (HSiO3/2)n

Abstract

An improved method has been devised for the preparation of (HSiOs/2)s. The previously unknown higher homologs (HSiOi/,)i0-i6 have also been prepared and characterized. They were isolated from a soluble, silanol-free resin obtained by a rather unusual hydrolysis and condensation procedure whereby water is generated via the sulfonation of an aromatic solvent such as benzene. Evidence for the existence of structural isomerism in the larger cage systems was obtained from nmr studies; i.e., only the octamer and decamer exhibit simple single-line spectra. Despitethe attention accorded to prismatic silsesquioxane oligomers [(RSiOy2)8,10,12] in recent years,1 relatively little information is available concerning the oligomeric forms of the simplest member of

Periodic Mesoporous Hydridosilica − Synthesis of an “Impossible” Material and Its Thermal Transformation into Brightly Photoluminescent Periodic Mesoporous Nanocrystal Silicon-Silica Composite

“…Similar FTIR spectra have been reported for cage-like hydrogen silsesquioxane (HSQ) and other dense (HSiO 1.5 ) n extended network (ladder or random) structures. 17,21,22 Considering the SiÀOÀSi stretching and HÀSiÀO deformation bands ( Figure 1A), previous studies have shown that their intensities and frequencies are related to the structure of the HSiO 1.5 framework, with the high frequency component of these bands (ca. 1160 cm À1 for SiÀOÀSi and ca.…”

“…23,24 Furthermore, the peak at 465 cm À1 has also been associated with cage-like structures. 21,22 Therefore, it can be concluded that the pore walls in the meso-HSiO 1.5 are composed primarily of mixed ladder network and cage-like HSiO 1.5 structures. The Raman spectra of the as-synthesized and surfactant-extracted samples (Supporting Information Figure S2) show that there is a weak interaction between the surfactant molecules and the HSiO 1.5 walls, causing broadening and a small shift of the HÀSi mode at ca.…”

“…Received: December 21,2010 ABSTRACT: There has always been a fascination with "impossible" compounds, ones that do not break any rules of chemical bonding or valence but whose structures are unstable and do not exist. This instability can usually be rationalized in terms of chemical or physical restrictions associated with valence electron shells, multiple bonding, oxidation states, catenation, and the inert pair effect.…”

Resists for sub-20-nm electron beam lithography with a focus on HSQ: state of the art

“…HSQ is also very sensitive to contamination Figure 18. Schematic representation of the molecular structure of HSQ: (a) cage structure for an eight-corner oligomer; (b) random structure of the resist solution [63]. Reprinted with permission from [63].…”

Characterization of low and intermediate molecular weight hydrogen silsesquioxanes by mass spectrometry

“…With these preliminary MS results, we have clearly demonstrated that mass spectrometry with the above-mentioned ionization techniques is an invaluable tool that can be utilized when attempting to solve the challenge set forth by the complexity of hydrogen silsesquioxane materials. [1], has the general chemical composition of (HSiO 3/2 ) 2n where n Ͼ 3. It received much attention after its unique applications as carbonless protective coatings and interlayer dielectrics were successfully demonstrated in the early 1990s for the semiconductor industry [2][3][4].…”