Synthesis of Functionalized Silsesquioxane Nanomaterials by Rhodium‐Catalyzed Carbene Insertion into Si−H Bonds

Abstract

We report carbene insertion into Si À H bonds of polyhedral oligomeric silsesquioxanes (POSS) for the synthesis of highly functionalized siloxane nanomaterials. Dirhodium(II) carboxylates catalyze insertion of aryl-diazoacetates as carbene precursors to afford POSS structures containing both ester and aryl groups as orthogonal functional handles for further derivatization of POSS materials. Four diverse and structurally varied silsesquioxane core scaffolds with one, three, or eight SiÀH bonds were evaluated with diazo reactants to produce a total of 20 new POSS compounds. Novel diazo compounds containing a fluorinated octyl group and boron-dipyrromethene (BODIPY) chromophore demonstrate the use of highly functionalized substrates. Transformations of aryl(ester)-functionalized POSS compounds derived from this method are demonstrated, including ester hydrolysis and Suzuki-Miyaura cross-coupling.

Crosslinked siloxane–silsesquioxane elastomer with pyrene functionalization for rapid adsorption of benzene, toluene, and xylene (BTX) from water and sensing of charged species

“…The shoulder signal at around −18 ppm potentially could be attributed to a signal of the D structures having different distance distributions to the T structures. [44][45][46][47][48][49] The MAS solid-state 13 C-NMR spectrum of Py-CSSE exhibits a signal at 0.9 ppm, corresponding to the sp 3 methyl carbon of siloxane chains. The spectrum also showed broad multiple signals around 132-134 ppm, corresponding to sp 2 carbons derived from the abundant vinyl groups of OVS (Fig.…”

“…Importantly, the signals associated with pyrene are absent from the spectrum. This is due to the limited sensitivity of the MAS solid-state 13 C-NMR technique, which inhibited the detection of signals resulting from the small amount of Mono-PySQ introduced into Py-CSSE (Fig. S2 †).…”

“…The core structure of SQs comprises inorganic Si-O-Si units that are chemically functionalized with diverse organic residues (R groups), enabling subsequent modifications through various organic reactions. [13][14][15][16] Furthermore, SQ-based materials with highly symmetrical cage-type structures, such as polyhedral oligomeric silsesquioxanes (POSSs), have shown enhanced physico-chemical characteristics compared to other silicon-based materials and have become promising contenders for various applications, for example, POSSs have been utilized as fillers in composite materials as a result of their nano-sized cage structures, thermally robust and elastic behavior, [17][18][19] flame retardancy, 20,21 and mechanical strength. 22,23 These features have highlighted POSSs as potential high-performance electrode materials for supercapacitors 24 and lithium-ion batteries.…”