POSS Article Index: All Posts and Topic Guides

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This index lists every article published on this blog, grouped by subject and followed by the year of publication. It is intended as a single, permanent entry point to the whole archive, so that no article depends on pagination in order to be reached.

Fundamentals, Nomenclature and Cage Structure

Synthesis and Functionalization

Crystal Structures and Supramolecular Chemistry

Catalysis and Photochemistry

Materials, Sensing and Applications

Topic Guides

The following pages collect background material and longer overviews.

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Octa(3-aminopropyl)silsesquioxane (OAS-POSS) Synthesis Routes

Octa(3-aminopropyl)silsesquioxane (OAS-POSS) Synthesis Routes
Wacker-Chemie Patent Origins and the Absence of Early Characterization Data Octa(3-aminopropyl)silsesquioxane hydrochloride (OAS) was first described in a patent filed by Wacker-Chemie GmbH. 1 That document, however, reports neither a method for its preparation nor the spectroscopic data required for its full identification. 2 Feher's Hydrolytic Condensation Route to OAS-POSS Hydrochloride Seven years later, Feher 3 investigated the hydrolytic condensation of (3-aminopropyl)triethoxysilane in methanolic solution, using hydrochloric acid as the catalyst, in order to obtain the octakis(3-aminopropyl)octasilsesquioxane chloride salt. Under these conditions the yield was 30% and the reaction required four weeks. Modifications of this procedure reported in the literature involve replacing the hydrolyzable group with a methoxy group or adding PtCl 4 as a cocatalyst, although such changes do not significantly increase the yield. 4–6 Kaneko and co-workers subsequently developed another ...
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Structures of oligomeric silsesquioxanes (POSS)

Structures of oligomeric silsesquioxanes (POSS)
Polyhedral Silsesquioxanes Research on compounds containing the Si–O bond has long been dominated by silicon dioxide, by minerals built from repeating SiO₂ units, and by silicones composed of repeating R₂SiO units (R = alkyl or phenyl). Over the past 20 to 30 years, however, interest in silsesquioxanes based on the RSiO₁.₅ unit has increased markedly. Because these compounds contain both an inorganic fragment and an organic group, they display hybrid properties. The inorganic Si–O–Si framework imparts chemical and thermal resistance, whereas the organic R group enhances solubility and provides the required reactivity. A wide range of polymeric structures with the general formula (RSiO₁.₅)ₙ can be synthesized, although those adopting polyhedral architectures are of greatest interest. 4 Polyhedral oligomeric silsesquioxanes (POSS) are three-dimensional organosilicon compounds with the general empirical formula (RSiO₁.₅)ₙ , where R = H, alkyl, alkenyl, or aryl and n = 6, 8, 10, or 12. A w...
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T10 Decameric Silsesquioxanes: Synthesis and Cage Reorganization

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Decameric silsesquioxanes of the T 10 cage type (general formula [RSiO 3/2 ] 10 ) represent a structurally distinct class of polyhedral oligomeric silsesquioxanes (POSS) . Unlike the more common cubic T 8 cages possessing O h symmetry, T 10 silsesquioxanes adopt a prismatic cage geometry with idealized D 5h symmetry, in which ten silicon atoms are arranged in two parallel pentagonal rings connected by five bridging Si–O–Si linkages, consistent with the T10 cage nomenclature conventions used throughout this series. Despite their interesting geometry and properties, T 10 silsesquioxanes are considerably less studied than their T 8 counterparts, primarily due to the challenges associated with their isolation in pure form. Topics covered in this post:  formation of T 10 POSS as a by-product of T 8 synthesis; cage reorganization pathways (nucleophilic substitution, fluoride-catalyzed, base-catalyzed, and superacid-mediated routes); separation and purification methods; crys...
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