Robust Polyaromatic Octasilsesquioxanes from Polybromophenylsilsesquioxanes, Br_xOPS, via Suzuki Coupling

Abstract

Polybromophenylsilsesquioxane (Br xOPS), where x ) 5.3 (p:m ) 65:25), because of its octahedral structure and nanometer size, represents a potentially very useful nanoconstruction site. We report here that Br5.3OPS reacts readily with borates of phenyl, biphenyl, naphthyl, 9,9-dimethylfluorene, and thiophene using standard Suzuki conditions to produce the corresponding polyaromatic and heteroaromatics with complete substitution of all bromines. The resulting materials, because of the 3-D octahedral structure, are completely soluble in a variety of common organic solvents. They are also stable to temperatures exceeding 400 °C in air, making them quite robust and easily processable. UV-vis spectra of these materials are red-shifted 20-30 nm from the simple organics, suggesting some conjugation with the silica cage core. Photoluminescence measurements show standard aromatic π-π* behavior with typical quantum efficiencies except for the 9,9-dimethylfluorene compound, which has an unexpectedly high quantum efficiency >95%. The resulting compounds offer potential for further functionalization.

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

“…The incorporation of organic/inorganic silsesquioxanes (SQs) into polymer matrices has been extensively investigated to improve nanocomposites properties due to the intrinsic properties of SQs including nanometer dimensions, low densities, excellent heat, and fire‐resistant properties as well as the ability to tailor the types and amounts of functional groups. SQs generally consist of silicon‐oxygen cores with (SiO 1.5 ) n abbreviated T n, where n = 6, 8, 10, 12 along with pendant organic substituents (R) such as phenyl,19 vinyl,20 amine,21–25 epoxy,26–29 and arylhalide30,31 depending on the final required chemical structure and target properties required of the specific application.…”

Star‐like polyfluorenes based on 2,4,6,8, 10,12‐hexabenzyl‐2,4,6,8,10,12‐hexaazaisowurtzitane caged‐core: toward non‐aggregating, blue‐light‐emitting polymers

“…PL quantum efficiencies (Φ PL ) of the samples both in THF solution and as films were measured by using 9,10‐diphenylanthracene (Φ PL = 0.91 in ethanol and Φ PL = 0.83 dispersed in PMMA films with a concentration lower than 1 × 10 −3 M) as standards. Values of Φ PL were calculated according to literature21 and averaged from three repeating operations.…”

Self‐Lubricating Nano‐Ball‐Bearings

“…1 H NMR spectra were collected at 400.0 MHz by using a spectral width of 6000 Hz, a relaxation delay of 3.5 s, 30 k data points, a pulse width of 38°, and CHCl 3 (7.27 ppm) as an internal reference. 13 C NMR spectra were collected at 100.6 MHz by using a spectral width of 25 000 Hz, a relaxation delay of 1.5 s, 75 k data points, a pulse width of 40°, and CDCl 3 (77.23 ppm) as an internal reference.…”

“…[1][2][3] Diverse studies of OPS (octasilsesquioxanes) range from their ordering in solids (nanocomposites) to catalysts, NMR standards, and spacecraft coatings. [4][5][6][7][8][9][10][11][12][13] The prototypical OPS [10] (R = phenyl) is air-stable to temperatures above 500°C; however, high symmetry and crystallinity limit its maximum solubility to 100 mg per 100 mL CH 2 Cl 2 , rendering attempts at functionalization very difficult. [10,12,13] In an effort to couple early work on liquid-crystalline (LC) silsesquioxanes with recent efforts to functionalize OPS, we explored Friedel-Crafts alkylation [14] by AlCl 3 , despite the potential for Si-C bond cleavage.…”

“…Friedel-Crafts alkylation (nRBr, see Supporting Information) of OPS produces alkyl x OPS, with typical [14] 7:3 ratios of branched/normal alkyl groups. Cleavage of Si-C bonds (by using nBu 4 NF) coupled with analysis by 13 C NMR and matrixassisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS, see Fig. S1 in the Supporting Information) distinguish individual alkylation products and the average numbers of alkyl groups per phenyl for each nRBr.…”