Unprecedented Formation of cis‐ and trans‐Di[(3‐chloropropyl)isopropoxysilyl]‐Bridged Double‐Decker Octaphenylsilsesquioxanes

Abstract

Silsesquioxane formation competing with the deprotonation of alcohol solvents in the presence of a strong base to form alkoxides is reported for the first time. Evidently, sodium isopropoxide is formed during the synthesis of the sodium salt of a double‐decker octaphenylsilsesquioxane tetrasilanolate in 2‐propanol as the solvent, which leads to the formation of unexpected cis‐ and trans‐di[(3‐chloropropyl)isopropoxysilyl]‐bridged double‐decker octaphenylsilsesquioxanes after in situ coupling with 3‐chloropropyltrichlorosilane. The desired products were characterized by 1H NMR, 13C NMR, and 29Si NMR spectroscopy; ESI‐MS; and single‐crystal X‐ray diffraction.

Synthesis of a “Butterfly Cage” Based on a Double‐Decker Silsesquioxane

“…After drying under reduced pressure, recrystallization in the mixed solvent of chloroform and 2‐propanol (1:1) afforded colorless crystals in a 40 % yield of 3 . For the synthesis of 4 , the dichlorooctamethyltetrasiloxane linkage was expected to react intermolecularly rather than intramolecularly to yield polymeric materials . Surprisingly, though the reaction provided polymer linkages forming a long siloxane chain, the closed cage structure 4 was obtained in only slightly lower yield as compared to 2 and 3 .…”

“…The doubly‐extended butterfly cage T 8 D 4 3 , T 8 D 6 4 , and T 8 D 8 5 , both ends of which are linked to oligosiloxane chains, were synthesized in 91 %, 86 %, 64 %, respectively by the reaction of DDSQ‐tetraol 1 a with methyl substituted oligosiloxane in the presence of triethylamine (Scheme ). Tetraol 1 a can be prepared in high yield from DDSQ‐(ONa) 4 1 b that was easily synthesized from trimethoxyphenylsilane in 2‐propanol via hydrolytic condensation using sodium hydroxide and refluxing for 4 h followed by stirring for 15 h at 20 °C according to a previously reported method . The condensation reactions between tetraol 1 a and dichlorooligosiloxanes are somewhat slow, requiring a reaction time of 14 h at room temperature and several hours at reflux.…”

Synthesis and Characterization of Unsymmetrical Double-Decker Siloxane (Basket Cage)

“…Dichlorodisiloxane 1 [37] was freshly prepared by the hydrolytic condensation of dichlorodiphenylsilane in the presence of water for 3 h. The product obtained after distillation was a viscous colorless oil in 35% yield. The synthesis procedure for DDSQ-ONa ( 2 ) is described in detail in previous reports [19,21,38]. A 2-propanol solution of trimethoxyphenylsilane with NaOH and water was refluxed for 4 h, followed by continuous stirring at room temperature for 15 h. After filtration, a white solid was obtained in 58% yield.…”

“…Additionally, these compounds find a wide range of applications in polymers [8,9,10,11], sensors [12], catalysis [7,8,9,13], organic light-emitting diodes [14], host-guest complexes [15,16], and porous materials [17]. Most of the double-decker silsesquioxanes (DDSQ) [10,11,14,18,19,20,21,22,23,24,25,26] and polyhedral oligomeric silsesquioxanes [7,8,9,12,13,15,16,17,27,28,29] have a symmetrical structure with the same organic functional group on both sides. In contrast, only a few studies on unsymmetrical silsesquioxane or siloxane cages have been reported because of the difficulty in obtaining a perfect Janus structure via a simple hydrolytic condensation of two organomonosilane precursors.…”

Cinnamate‐Functionalized Cage Silsesquioxanes as Photoreactive Nanobuilding Blocks

“…The cell parameters were retrieved by using the SMART software and refined with SAINT for all observed reflections. [32,33] The crystal structures were solved by direct methods by using SHELXS-97 and refined on F 2 by full-matrix least-squares procedures with SHELXL-97. [34] Hydrogen atoms were placed at calculated positions and included as riding atoms.…”