Multiple literature reports describe the synthesis of [RSiO(OH)] 4 or [RSiO(ONa)] 4 compounds. Surprisingly, in the majority of cases the OH or ONa groups all lie on the same face of the cyclomers or half cubes. Consequently, it appears possible to couple R containing half cubes with R' containing half cubes to form bi-functional (Janus) silsesquioxane cages or cubes. We report here synthesis of [PhSiO(ONa)] 4 and [p-IPhSiO(ONa)] 4 half cubes. We thereafter discuss efforts to react the [PhSiO(ONa)] 4 salt with (R = Me, vinyl, and cyclohexyl) RSiCl3 in MeOH to produce the compounds {PhSiO[OSi(OMe)2R]} 4 species which were characterized using traditional spectroscopic procedures. These compounds were then subjected to acid catalyzed hydrolysis tohydrolytically remove the OMe groups to generate Janus cubes. While it is possible to isolate the target compounds, which were also characterized in detail, the yields were lower than expected perhaps because of competitive hydrolytic cleavage of the Si-O-SiR(OMe) 2 linkage. To cite this article:

Given the high mortality rates in the PTZ-R group, a risk-factor-guided approach driven by this multivariable model may help identify patients that could benefit from amikacin combination therapy to help optimize empiric therapy in this setting.

A series of thioether-functionalized silsesquioxanes (SQs) was synthesized by radically initiated thiol-ene reactions of vinyl T 10 / T 12 SQ cages with a variety of commercially available thiols. The objectives of this study were to develop model reactions as the basis for using the vinyl T 10/12 compounds as novel crosslinking agents in the synthesis of new types of thiol-ene crosslinked polymers. A second motivation was to develop model compounds with controlled refractive indices and Abbe numbers as possibly modifiers of polymers used for a wide variety of optical and photonic applications. The reactions proceed under mild conditions over 24 h to give thioether SQs in high yields (>90%) and high purity without complex workup. The ease of synthesis coupled with the wide variety and availability of functionalized thiols provides a simple route to elaborating and functionalizing vinyl SQ cages. In addition, the resulting compounds exhibit refractive indices to 1.52 coupled with Abbe numbers to 51 due to the uniquely high electron density provided by the incorporated sulfur atoms, making them ideal compounds for use with optically transparent materials. In addition, cured forms of these compounds provide methods of raising the Abbe number of epoxy resins designed to index match fiberglass with the intent of making transparent fiberglass reinforced composites.

No abstract