Novel Bifunctional Periodic Mesoporous Organosilicas, BPMOs:  Synthesis, Characterization, Properties and in-Situ Selective Hydroboration−Alcoholysis Reactions of Functional Groups

Abstract

A new class of bifunctional periodic mesoporous organosilicas (BPMOs) containing two differently bonded organic moieties in a mesoporous host has been synthesized and characterized. By incorporating bridge-bonded ethylene groups into the walls and terminally bonded vinyl groups protruding into the channel space, both the chemistry and physical properties of the resulting BPMO could be modified. The materials have periodic mesoporous structures in which the bridging ethylene plays a structural and mechanical role and the vinyl groups are readily accessible for chemical transformations. The vinyl groups in the material underwent hydroboration with BH(3).THF and the resulting organoborane in the BPMO was quantitatively transformed into an alcohol using either H(2)O(2)/NaOH or NaBO(3).4H(2)O. The materials retained ordered structures after subsequent in situ reactions with largely unchanged pore volumes, specific surface areas and pore size distributions. Other organic functionalized BPMO materials may be synthesized in a similar manner or by further functionalizing the resulting borylated or alcohol functionalized BPMO materials. The thermal properties of the BPMO materials have also been investigated and are compared to those of the periodic mesoporous organosilica (PMO) materials. Noteworthy thermal events concern intrachannel reactions between residual silanols or atmospheric oxygen and organics in BPMOs. They begin around 300 degrees C and smoothly interconvert bridging ethylene to terminal vinyl groups and terminal vinyl to gaseous ethene and ethane, ultimately producing periodic mesoporous silica at 900 degrees C that exhibits good structural order and a unit-cell size decreased relative to that of the parent BPMO.

Acid catalyzed synthesis of ordered bifunctionalized mesoporous organosilicas with large pore

“…5a). This behaviour is usually observed for materials with gradually decreasing pore diameter on the borderline between mesopore and micropore ranges [12]. Both Brij-SH 10 and Brij-SH 20 show typical type IV isotherm patterns with a sharp adsorption uptake due to capillary condensation of nitrogen in a mesopore system with narrow pore size distributions, indicating that the materials have ordered mesoporous structure.…”

“…The bifunctional periodic mesoporous organosilicas (BPMOs) with the organic groups both in the pores and in the walls were first reported by Ozin and coworkers [12]. After that, a number of different kinds of BPMOs emerged [13].…”

Aerosol‐Spraying Synthesis of Periodic Mesoporous Organometalsilica Spheres with Chamber Cavities as Active and Reusable Catalysts in Aqueous Organic Reactions

“…[ 11 ] More importantly, the chemical and physical properties of PMO can be tuned by changing the organic functionalities inside the framework, which may offer new opportunities for their applications. [ 12 ] Up to now, various PMO materials containing different functional groups such as ethyl-, [ 13 ] 2-butylene-, [ 14 ] phenyl-, [ 15 ] thiophene-, [ 16 ] and biphenyl [ 17 ] have been synthesized.…”

Synthesis, characterization, and catalytic activity of sulfonic acid-functionalized periodic mesoporous organosilicas

“…A versatile approach for the functionalization of PMOs is the development of bifunctionalized PMOs by cocondensation of trialkoxyorganosilanes with bridged silsesquioxane precursor in the presence of the surfactant. Ozin and co-workers [6] reported bifunctionalized periodic mesoporous organosilicas (BPMOs) having bridging ethyl groups in the walls and vinyl groups protruding into the channels. Later, a series of organic functionalities such as amine, thiol, diamine, imidazole, pyridine, benzyl, and phenethyl were incorporated into the channel of mesoporous organosilicas with the bridging ethyl groups in the framework [7].…”