Periodic Mesoporous Organosilicas with a Bifunctional Conjugated Organic Unit and Crystal-like Pore Walls

Abstract

The synthesis of a 2D hexagonal highly ordered periodic mesoporous 1,4-divinylbenzene-bridged organosilica (PMO) with crystal-like pore walls is reported. Both functionalities are realized by utilization of one single precursor (1,4-bis-((E)-2-(triethoxysilyl)vinyl)benzene (BTEVB) which was synthesized via Pd-catalyzed double Heck coupling of 1,4-dibromobenzene with vinyltriethoxysilane. Solid state 29Si MAS NMR and FT-IR spectroscopy confirms that during the hydrothermal PMO synthesis and subsequent extraction procedure (i) no Si−C bond cleavage occurred and (ii) the organic bridge is preserved. The novel PMO material with a pore diameter of 2.6 nm, a molecular scale periodicity of 1.19 nm within the pore walls, and a specific surface area of S BET = 730 m2/g offer various opportunities for further chemical modification within the mesopores as shown by bromination reactions.

Grafting of Molecularly Ordered Mesoporous Phenylene‐Silica with Molybdenum Carbonyl Complexes: Efficient Heterogeneous Catalysts for the Epoxidation of Olefins

“…[4][5][6] Most of these materials have amorphous pore wall structures, that is, the organic groups are randomly arranged within the framework. In a few selected cases [R = C 6 H 4 , [7][8][9][10] (C 6 H 4 ) 2 , [11,12] CH=CH, [7,13,14] CH=CH À C 6 H 4 À CH= CH, [15,16] and 2,6-naphthylene [17] ), the self-organization of bis-silylated organic precursors has been exploited to prepare PMOs with molecular scale ordering of the organic groups within the pore walls. [18,19] The first report of an ordered mesoporous material possessing a crystal-like periodic pore wall structure came from Inagaki et al, who used 1,4-bis(triethoxysilyl)benzene (BTEB) as the precursor to a phenylene-silica hybrid mesoporous material.…”

“…Bromination experiments performed for vinylene-and phenylenedivinylene-bridged PMOs showed that up to 35% of the organic groups were accessible for functionalization. [14,16] Crystal-like mesoporous phenylene-silica can be sulfonated in one step (by treatment with fuming sulfuric acid or chlorosulfonic acid) or aminated in two steps (by nitration with HNO 3 -H 2 SO 4 followed by treatment with SnCl 2 -HCl). [7,22,23] The amino-functionalized material was found to be a reusable base catalyst for the Knçevenagel condensation reaction.…”

Modification of Mesoporous Silicates for Immobilization of Enzymes

“…The organic functionality of PMO materials can be tuned to suit the application required. For example, Cornelius et al [33] synthesized a PMO using 1,4-bis((E)-2-(triethoxysilyl)vinyl) benzene to introduce two organic functionalities into the pore wall structure, a vinyl group and an aromatic ring. These groups can be further functionalised if required.…”

Synthesis and Characterization of Chiral Benzylic Ether‐Bridged Periodic Mesoporous Organosilicas

“…There are enormous possibilities to deliberately tune the chemical and physical properties of the PMOs by varying the organic spacer groups of the organosilica precursors, which makes these materials interesting for applications such as catalysis, adsorption, chromatography, or host-guest chemistry. [4,5] The organic bridging groups of the organosilica precursors that have been successfully converted into PMO materials include, for instance, methylene, [6] ethylene, [1,3] ethenylene, [2,3] phenylene, [7] biphenylene, [8] thiophene, [7,9] and divinylphenylene [10,11] units. It was also possible to prepare PMOs possessing molecularscale periodicity inside the channel walls instead of the common observed amorphous pore walls as a result of a highly cooperative process.…”