Fluoride catalyzed rearrangements of polysilsesquioxanes, mixed Me, vinyl T₈, Me, vinyl T₁₀ and T₁₂ cages

Abstract

Efforts to isolate the cage compounds by removal of solvent regenerates polysilsesquioxanes, albeit those containing mixtures of Me and vinyl groups. Introduction of CaCl 2 sufficient to form CaF 2 prior to workup prevents repolymerization, allowing recovery of the mixed cage systems. The approach developed here provides a novel way to form mixed functional group silsesquioxane cages. The fact that T 10 and T 12 cage formation is favored appears to suggest that these cages are more stable than the traditionally produced T 8 cages.

Pure Blue‐Light Emissive Poly(oligofluorenes) with Bifunctional POSS in the Main Chain

“…Scheme shows the synthetic scheme and nomenclature of polymers studied in this report. Bi‐functional POSS ( B‐POSS ) have been synthesized via a minor modification of the reported methods . The formation of B‐POSS was confirmed by matrix‐assisted laser desorption/ionization‐time of flight (MALDI‐TOF), which found the molecular mass peak at 1151.5 ( m / z ), together with a peak at 1175.45 m / z , which was ascribed the peak of [B‐POSS‐Na] + (Figure S1, Supporting Information).…”

Synthesis and characterization of organic/inorganic epoxy nanocomposites from poly(aminopropyl/phenyl)silsesquioxanes

“…Even though TBAF was found to be a suitable catalyst for the generation of the T 10 and T 12 cages, solvent removal resulted in repolymerization of products to form undesired high MW polymers took place if the fluoride ion was retained in the reaction mixture. Thus, calcium chloride (CaCl 2 ) was used to trap excess fluoride ion forming insoluble calcium fluoride salt (CaF 2 ) and insoluble tBu 4 NCl which are removed easily by filtration 40…”

Modern concepts and methods in the chemistry of polyhedral metallasiloxanes

“…Some experimental results [26,27] suggest that octameric silsesquioxane cages are not the most thermodynamically stable and they often isomerize to yield larger cages (deca-or dodecameric). Thus, the dissolution of (vinylSiO 1.5 ) n and (MeSiO 1.5 ) n in the presence of catalytic amounts of tBu 4 NF mainly yields compounds with [vinyl x Me 8−x (SiO 1.5 )] 10 and [vinyl x Me 8−x (SiO 1.5 )] 12 compositions, while sometimes almost completely excluding the formation of octameric materials [26].…”

“…Thus, the dissolution of (vinylSiO 1.5 ) n and (MeSiO 1.5 ) n in the presence of catalytic amounts of tBu 4 NF mainly yields compounds with [vinyl x Me 8−x (SiO 1.5 )] 10 and [vinyl x Me 8−x (SiO 1.5 )] 12 compositions, while sometimes almost completely excluding the formation of octameric materials [26]. For example, the nucleophilic substitution in [RSiO 1.5 ] 8 (R = Cl(CH 2 ) 3 -) with phtalimide leads to a partial structural rearrangement of the octasilsesquioxane core to yield deca-and dodecasilsesquioxane cages [27].…”

“…For example, the nucleophilic substitution in [RSiO 1.5 ] 8 (R = Cl(CH 2 ) 3 -) with phtalimide leads to a partial structural rearrangement of the octasilsesquioxane core to yield deca-and dodecasilsesquioxane cages [27]. Octameric cages have mostly been synthesized because of their lower solubility (higher crystallinity) and due to their high symmetry compared with other cages [26,27].…”