Spherical, Polyfunctional Molecules Using Poly(bromophenylsilsesquioxane)s as Nanoconstruction Sites

Abstract

Poly(bromooctaphenylsilsesquioxane)s (Br x OPS) are easily synthesized from octaphenylsilsesquioxane (OPS) via bromination with Br2/Fe in dichloromethane. For Br:OPS ratios less than 8:1, singly brominated products are obtained with 65−70% para substitution, 25−20% meta substitution and the remainder ortho. Higher ratios provide dibrominated products up to Br16OPS. Surprisingly, the disubstitution pattern is completely different with 80% 2,5 substitution (meta and ortho to Si), indicating extensive rearrangement with addition of the second bromine. Br x OPS bromo functionality is readily transformed via low temperature catalytic coupling reactions with para-substituted styrenes, tetraphenylborate, methyl methacrylate, or toluidine into the corresponding fully substituted p-stilbenes, p-biphenyls, methyl cinnamates, and diarylamines. The p-stilbenes offer unusually large red shifts and order of magnitude increases on photoluminescence quantum efficiencies over stilbene itself. Methyl methacrylate addition provides a mechanism for forming cross-linkable films and can be used in conjunction with the other functionalization reactions. Reactions with phenylacetylenes occur with concomitant formation of vinyl bromides, which appear to react further, adding second acetylene groups. The fact that each phenyl group occupies a different octant in Cartesian space, for Br≤ 8OPS primarily para, offers the opportunity to create novel eight branched, highly conjugated cores of value in their own right but also of value as three-dimensional, eight or 16 branched, aromatic cores for the synthesis of dendrimer-like and/or hyperbranched molecules.

Bromination of octaphenylsilsesquioxane

“…The bromination of the phenyl substituents on the octaphenylsilsesquioxane molecule was attempted following known procedures and has been reported before, although no effort was made to characterize the product [11,17,20] until very recently [22,23]. Although octaphenylsilsesquioxane has an overall low solubility, about 10 mg/ml can be dissolved into dichloromethane at room temperature and about 25 mg/ml at reflux temperatures.…”

Flame retardancy of epoxy resin nanocomposite with a novel polymeric nanoflame retardant

“…Among them, POSS is a class of inorganic‐organic hybrid silicon‐based FR, which was firstly synthesized by Scott in 1946 but has widely used since the discovery of polymerizable POSS in the 1990s . There are some studies regarding modified POSS via the copolymerization between styrene and octavinyl‐POSS,, but they focused on the reinforcement of composites and the flame retardancy have not been explored or still a halogen‐containing micromolecule . Therefore, we aim to design a polymeric bromine‐containing POSS FR with brominated styrene (introduce the FR element in styrene) and monovinyl‐POSS (the reaction is easy to control and the product structure is clear) based on these studies.…”

An Efficient Approach to Octabromophenylethyl‐Functionalized Cage Silsesquioxane and Its Use in Constructing Hybrid Porous Materials

“…They also reported that the average extent of bromination could be controlled by the reaction stoichiometry, with narrow distributions of bromines per molecule. [20] Moreover, to improve the reactivity and solubility of OPS, Laine et al reported that OPS can react with ICl at subambient temperatures to provide I 8 OPS, or [p-IC 6 H 4 SiO 1.5 ] 8 (following recrystallization) in good yields with excellent selectivity. [21] In contrast to previous studies, Cheng et al obtained an octa-(bromophenylethenyl)silsesquioxane with high regio-and stereoselectivity by cross-metathesis of vinyl-terminated D 4 R and 4-bromostyrene.…”