Face-Centered-Cubic Large-Pore Periodic Mesoporous Organosilicas with Unsaturated and Aromatic Bridging Groups

Abstract

Large-pore ethenylene-bridged (-CH═CH-) and phenylene-bridged (-C(6)H(4)-) periodic mesoporous organosilicas (PMOs) with face-centered-cubic structure (Fm3m symmetry) of spherical mesopores were synthesized at 7 °C at low acid concentration (0.1 M HCl) using Pluronic F127 triblock copolymer surfactant in the presence of aromatic swelling agents (1,3,5-trimethylbenzene, xylenes-isomer mixture, and toluene). In particular, this work reports an unprecedented block-copolymer-templated well-ordered ethenylene-bridged PMO with cubic structure of spherical mesopores and an unprecedented block-copolymer-templated face-centered cubic phenylene-bridged PMO, which also has an exceptionally large unit-cell size and pore diameter. The unit-cell parameters of 30 and 25 nm and the mesopore diameters of 14 and 11 nm (nominal BJH-KJS pore diameters of 12-13 and 9 nm) were obtained for ethenylene-bridged and phenylene-bridged PMOs, respectively. Under the considered reaction conditions, the unit-cell parameters and pore diameters were found to be similar when the three different methyl-substituted benzene swelling agents were employed, although the degree of structural ordering appeared to improve for phenylene-bridged PMOs in the sequence of decreased number of methyl groups on the benzene ring.

Hybrid Ordered Mesoporous Materials as Supports for Permanent Enzyme Immobilization Through Non‐covalent Interactions

“…Indeed, the immobilization of proteins in PMO materials was reported for the first time by Hudson et al in 2005 [46]. However, pore size of PMOs can be increased by means of several synthesis strategies, such as the use of swelling agents, addition of salts, and low-temperature synthesis [79][80][81], which allow to obtain materials able to adsorb enzymes of high molecular weight. However, pore size of PMOs can be increased by means of several synthesis strategies, such as the use of swelling agents, addition of salts, and low-temperature synthesis [79][80][81], which allow to obtain materials able to adsorb enzymes of high molecular weight.…”

Synthesis of large-pore face-centered-cubic periodic mesoporous organosilicas with unsaturated bridging groups

“…Among the aforementioned PMOs, ethenylene-bridged PMOs have been studied with keen interest [2,3,6,10,11,[35][36][37][38][39][40][41][42][43], primarily because of their unsaturated bridging groups that can be chemically modified. Various studies have been conducted in this direction, resulting in the introduction of functional groups [3,40,42,43].…”

“…Some of the potential applications of the ethenylene-bridged periodic mesoporous organosilicas include catalysis [40] and adsorption [2,42]. Although there have been a number of studies focused on ethenylene-bridged PMOs with cylindrical mesopores arranged in a 2-D hexagonal structure, reports on ethenylene-bridged PMOs with spherical mesopores were few [36,38], and only in one case, a product was primarily a single phase [38]. The latter was large-pore ethenylene-bridged PMO with a face-centered cubic structure prepared at low temperature (7 °C) and moderate acid concentration (0.1 M HCl) using Pluronic F127 as a surfactant template and an appropriate micelle swelling agent, namely 1,3,5-trimethylbenzene (TMB), xylene or toluene.…”

“…The maximum mesopore diameters 4 obtained for this kind of materials were around 14 nm and the unit-cell parameters were around 30 nm. The synthesis of this very interesting product was based on a strategy involving a moderate acidic synthesis medium combined with a sub-ambient temperature, which was also found suitable for the synthesis of ethylene-and phenylene-bridged PMOs with face-centered cubic structures [38,44]. In comparison to typical conditions of the synthesis of PMOs with spherical mesopores using Pluronics as templates, which involve ~2 M HCl solution as the synthesis medium [9,45], the synthesis under moderately acidic conditions affords remarkably high mesopore volumes.…”

Hybrid periodic mesoporous organosilica designed to improve the properties of immobilized enzymes

“…26,27 In comparison with their purely siliceous counterparts, pore size is more difficult to adjust in PMO. 16,28 We have formerly described the immobilization of Candida antarctica lipase B (CaLB) on a PMO material containing ethylene groups. 29 Lipases are known to have a hydrophobic domain, which oen constitutes a lid responsible for their interfacial activation.…”