para-Octaiodophenylsilsesquioxane, [p-IC₆H₄SiO_1.5]₈, a Nearly Perfect Nano-Building Block

Abstract

The cubic symmetry of octafunctional octaphenylsilsesquioxanes [ROPS, (RC6H4SiO(1.5))8] coupled with a 1 nm diameter offers exceptional potential to assemble materials in three dimensions with perfect control of periodicity and the potential to tailor global properties at nanometer length scales. OPS itself is very inert and insoluble and can only be functionalized via electrophilic reactions with difficulty and with poor substitutional selectivity. However, functionalized OPS products are robust and highly soluble, offering easy purification and processing. In contrast to previous studies, we report here that OPS reacts with ICl at sub-ambient temperatures to provide (following recrystallization) [p-IC6H4SiO(1.5)]8, or I8OPS, in good yields and with excellent selectivity: >99% mono-iodo substitution with >93% para substitution as determined by H2O2/F- cleavage of the Si-C bonds to produce iodophenols. I8OPS in turn can be functionalized using conventional catalytic coupling reactions to provide sets of >93% para-substituted, functionalized compounds (alkynes, alkenes, aryl amines, phosphonates, aryl amines, polyaromatics, etc.), suggesting the potential to develop diverse nano-building blocks for the assembly of a wide variety of materials, some with novel photonic, electronic, and structural properties.

Hybrid Porous Materials with High Surface Area Derived from Bromophenylethenyl‐Functionalized Cubic Siloxane‐Based Building Units

“…Characterization: Solution-state NMR spectra were recorded on a Jeol JNM-EX-270 spectrometer at 270.0 MHz for 1 H, 67.80 MHz for 13 C, and 53.45 MHz for 29 Si. Chemical shifts are reported in ppm downfield from SiMe 4 .…”

“…[8][9][10][11][12] Among oligomeric siloxane units, the cubic octameric siloxane cage Si 8 O 12 , commonly termed double four-ring (D4R), is of particular interest as an ideal molecular building unit because of its rigidity, hyperbranched architecture, high symmetry, and ease of functionalization. [13] D4R moieties bearing specific functional groups such as aldehyde, carboxyl, and epoxy have been used in diverse forms as model catalysts, components for polymer blends, organic light-emitting diodes, and so on. [14] Early attempts to construct silicabased micro-and/or mesoporous materials with molecular Abstract: Sonogashira cross-coupling of bromophenylethenyl-terminated cubic, double four-ring, siloxane cages with di-/triethynyl compounds results in microporous poly(ethynylene ary-A C H T U N G T R E N N U N G leneethenylene silsesquioxane) networks, simply termed as polyorganosiloxane networks (PSNs).…”

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

“…[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. [22] However, the preparation of these cage monomers required rigorous reaction conditions, noble metal catalysts, and expensive monomers.…”

Synthesis, characterization, and properties of a novel polyhedral oligomeric octamethyldiphenylsulfonylsilsesquioxane

“…As a specific category of POSS, phenylsilsesquioxanes have high thermal stabilities and can be used in the field of flame retardants and high-temperature polymers [19][20][21][22]. However, the most common phenylsilsesquioxane, (PhSiO 3/2 ) 8 , is very inert and insoluble, which exhibits poor compatibility with a polymer matrix [23]. However, functionalized (PhSiO 3/2 ) 8 products are robust and highly soluble; they offer easy purification and processing [24][25][26][27].…”