Synthesis and Surface Chemistry of Spherical Mesoporous Organic−Inorganic Hybrid Particles with an Integrated Alcohol Functionality on the Pore Surface

Abstract

Novel mesoporous organic−inorganic spherical hybrid particles are described that contain a 3-hydroxypropyl organic functionality which is integral to the pore surface. The 3-hydroxypropyl hybrid particle is synthesized in three steps starting from a 4:1 (mol/mol) mixture of tetraethoxysilane and [3-(methacryloxy)propyl]trimethoxysilane, where the monomers are polymerized to a poly(organoalkoxysilane) oil, followed by sol−gel reaction to the hybrid silicate bead, which is finally subjected to an alkaline hydrothermal treatment to liberate the alcohol from the ester protecting group. The silicate precursor and final product were characterized by NMR spectroscopy and nitrogen sorption analysis. The heterogeneous surface chemistry of the hybrid's alcohol functionality was explored by running a series of classical alcohol reactions including bromination, esterification (carbamic and carbonic), and etherification (Williamson, epoxide ring opening). The brominated analogue was further converted via cyanation and Grignard couplings. Nuances to the heterogeneous surface chemistry are discussed as well as product characterizations by NMR spectroscopy and combustion analysis. A stability study was further conducted on the 3-hydroxypropyl hybrid silicate using an alkaline resistance test under HPLC packed column conditions. The hybrid material was found to be over 10-fold more stable than a comparable silica gel material. In a second HPLC test, the cyano derivatized hybrid material was found to be more resistant to acid-induced siloxane cleavage vs a comparable (3-cyanopropyl)silane grafted silica gel.

Microwave-induced synthesis of highly dispersed gold nanoparticles within the pore channels of mesoporous silica

“…Peaks are relatively broad attributed to the restricted mobility of the functional groups attached to the surface of SBA-15 [34]. After a simple addition reaction between amino groups and glycidol, three new resonance peaks at 51.2, 64.2 and 71.9 ppm appear, which are assigned to d, f, and e position carbons [35] as shown in Fig. 1B, respectively.…”

Highly‐Controlled Synthesis of Organic Layers on Mesoporous Silica: Their Structure and Application to Toxic Ion Adsorptions

“…21 A variety of aminoalkyl(trialkoxy)silanes are commercially available and have been widely used for surface modification, while more chain structures have been pursued. The attachment of amines on modified mesoporous silicas, [23][24][25][26][27][28][29] summarized in Scheme 2, has been widely studied. These aminofunctionalized mesoporous silicas have been used for base catalysts and cation traps.…”

“…31 Ding et al reported the conversion of terminal alcoholic OH on a mesoporous silica (2R p = 10 nm, not in a periodic structure) surface into a variety of organic groups. 32 They carried out an elemental analysis to evaluate the degree of transformation and hence the level of new substituent derivatization, which are summarized in Figure 2. All surface compounds showed clear resonances in the 13 C-NMR spectra, accompanied by peaks due to unreacted HOCH 2 CH 2 CH 2 -chains.…”

Highly stable high performance liquid chromatography stationary phase based on direct chemical modification of organic bridges in hybrid silica

“…Polymer-coated [16], horizontally polymerized [17,18], bidentate [5,13] and polar embedded stationary phases are typical examples. In recent years, a unique class of organic/inorganic hybrid silica materials have been developed, which is normally prepared by condensing alkoxysiloxanes with monosubstituted XSi(OR) 3 or organic-bridged (R O) 3 SiRSi(OR ) 3 [19][20][21][22]. Compared with inorganic silica materials, the columns packed with hybrid materials have increased chemical stability toward a broader pH range [15,19,22].…”