Fluoride Rearrangement Reactions of Polyphenyl- and Polyvinylsilsesquioxanes as a Facile Route to Mixed Functional Phenyl, Vinyl T₁₀and T₁₂Silsesquioxanes

Abstract

Polyphenylsilsesquioxane [PhSiO(1.5)](n) (PPS) and polyvinylsilsesquioxane [vinylSiO(1.5)](n) (PVS) are polymeric byproducts of the syntheses of the related T(8) octamers [PhSiO(1.5)](8) and [vinylSiO(1.5)](8). Here we demonstrate that random-structured PPS and PVS rearrange in the presence of catalytic amounts of Bu(4)N(+)F(-) in THF to form mixed-functionality polyhedral T(10) and T(12) silsesquioxane (SQ) cages in 80-90% yields. Through control of the initial ratio of starting materials, we can statistically tailor the average values for x for the vinyl(x)Ph(10-x)T(10) and vinyl(x)Ph(12-x)T(12) products. Metathetical coupling of x approximately = 2 vinyl cages with 4-bromostyrene produces SQs with an average of two 4-bromostyrenyl substituents. These products can be reacted via Heck coupling with vinylSi(OEt)(3) to produce SQs with vinylSi(OEt)(3) end-caps. Alternately, Heck coupling with the originally produced x approximately = 2 vinyl SQs leads to "beads on a chain" SQ oligomers joined by conjugated organic tethers. The functionalized T(10) and T(12) cages, metathesis, and Heck compounds were characterized by standard analytical methods (MALDI-TOF MS, (1)H and (13)C NMR spectroscopy, TGA, and GPC). MALDI confirms the elaboration of the cages after each synthetic step, and GPC verifies the presence of higher molecular weight SQ oligomers. TGA shows that all of these compounds are thermally stable in air (>300 degrees C). The UV-vis absorption and emission behavior of the Heck oligomers reveals exceptional red-shifts (> or = 60 nm) compared to the vinylSi(OEt)(3) end-capped model compounds, suggesting electronic interactions through the SQ silica cores. Such phenomena may imply 3-D conjugation through the cores themselves.

Construction of bimodal silsesquioxane-based porous materials from triphenylphosphine or triphenylphosphine oxide and their size-selective absorption for dye molecules

“…[22][23][24][25][26][27][28][29] Recently, many hybrid porous polymers were prepared via the topology combination from cubic OVS with planar molecules, 30 tetrahedral molecules, 31,32 cubic molecules [33][34][35][36] and polymer. [22][23][24][25][26][27][28][29] Recently, many hybrid porous polymers were prepared via the topology combination from cubic OVS with planar molecules, 30 tetrahedral molecules, 31,32 cubic molecules [33][34][35][36] and polymer.…”

Cinnamate‐Functionalized Cage Silsesquioxanes as Photoreactive Nanobuilding Blocks

“…[19][20][21][22] Although cage rearrangement results in mixtures, it provides a practicable route to other cage compounds, which are usually difficult to synthesize. [23,24] The resulting product was subjected to 29 Si NMR spectroscopy, and we observed several peaks ( Figure 1). This result means that the product was a mixture, and the nucleophile attack of the cinnamate anion cleaved -Si-O-Si-bonds and induced cage rearrangements (T 10 , T 12 ) without exception.…”

Facile thiol-ene reactions of vinyl T₁₀/T₁₂ silsesquioxanes for controlled refractive indices for transparent fiber glass reinforced composites

“…Polymer resins incorporating thermally robust SQ cages can exhibit improved thermal stabilities and oxidation resistance likely associated with the heat capacity of the cage and components that form a glassy layer of SiO x C y during pyrolysis that retards diffusion of O 2 through the surface char. 37) The double bonds of the vinyl T 8 and T 10 /T 12 SQs have previously been modified by Heck 38) and metathesis 38), 39) reactions. The resulting compounds have been shown to be important synthetic platforms for constructing intermediates to 3-D star nanomaterials and beads on a chain (BoC) oligomers that exhibit unique photophysical behavior.…”

“…The resulting compounds have been shown to be important synthetic platforms for constructing intermediates to 3-D star nanomaterials and beads on a chain (BoC) oligomers that exhibit unique photophysical behavior. 38), 39) The synthesis of SQ thioethers described below is meant to represent yet another route to elaborate SQ cages with vinyl moieties. The reactions described here proceed in high yield in 24 h under mild conditions with AIBN.…”