Synthesis and Reactivity of Nitrogen Nucleophiles-Induced Cage-Rearrangement Silsesquioxanes

Abstract

Novel phthalimide and o-sulfobenzimide-functionalized silsesquioxanes were successfully synthesized via nucleophilic substitution reactions from octakis(3-chloropropyl)octasilsesquioxane. Surprisingly, the formation of deca- and dodecasilsesquioxanes cages was discovered during substitution with phthalimide, but only octasilsesquioxane maintained a cage in the o-sulfobenzimide substitution reaction. Moreover, we report the electronic effect of nitrogen nucleophiles to promote cage-rearrangement of inorganic silsesquioxane core for the first time. Structures of products were confirmed by (1)H, (13)C, and (29)Si NMR spectroscopy, ESI-MS analysis, and single-crystal X-ray diffraction.

Preparation of soluble polysilsesquioxane containing phthalimido side-chain groups and its optical and thermal properties

“…On the basis of the aforementioned background of both materials bearing phthalimido pendent groups and SQs, the preparation of soluble polyhedral oligomeric SQ (POSS) containing phthalimido pendent groups has been reported [22]. Although some of the amorphous POSS compounds gave the transparent films [22e25], the oligomeric nature of the POSS compound may limit its ability to form free-standing films.…”

Hydrogen adsorption and diffusion in amorphous, metal-decorated nanoporous silica

“…In this study we computationally investigate the spherosilicate structures made up of polyhedral oligomeric silsesquioxane (POSS), which has the shape of a cube and the empirical chemical formula (RSiO 3/2 ) 8 where R is either a functional ending group or a cross linker connecting it to another spherosilicate unit. POSS are part of a large family of polycyclic compounds consisting of siliconeoxygen bonds [17,18].…”

Modern concepts and methods in the chemistry of polyhedral metallasiloxanes

“…Some experimental results [26,27] suggest that octameric silsesquioxane cages are not the most thermodynamically stable and they often isomerize to yield larger cages (deca-or dodecameric). Thus, the dissolution of (vinylSiO 1.5 ) n and (MeSiO 1.5 ) n in the presence of catalytic amounts of tBu 4 NF mainly yields compounds with [vinyl x Me 8−x (SiO 1.5 )] 10 and [vinyl x Me 8−x (SiO 1.5 )] 12 compositions, while sometimes almost completely excluding the formation of octameric materials [26].…”

“…Thus, the dissolution of (vinylSiO 1.5 ) n and (MeSiO 1.5 ) n in the presence of catalytic amounts of tBu 4 NF mainly yields compounds with [vinyl x Me 8−x (SiO 1.5 )] 10 and [vinyl x Me 8−x (SiO 1.5 )] 12 compositions, while sometimes almost completely excluding the formation of octameric materials [26]. For example, the nucleophilic substitution in [RSiO 1.5 ] 8 (R = Cl(CH 2 ) 3 -) with phtalimide leads to a partial structural rearrangement of the octasilsesquioxane core to yield deca-and dodecasilsesquioxane cages [27]. Octameric cages have mostly been synthesized because of their lower solubility (higher crystallinity) and due to their high symmetry compared with other cages [26,27].…”

“…For example, the nucleophilic substitution in [RSiO 1.5 ] 8 (R = Cl(CH 2 ) 3 -) with phtalimide leads to a partial structural rearrangement of the octasilsesquioxane core to yield deca-and dodecasilsesquioxane cages [27]. Octameric cages have mostly been synthesized because of their lower solubility (higher crystallinity) and due to their high symmetry compared with other cages [26,27].…”