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

Abstract

The first synthesis of a chiral periodic mesoporous organosilica (PMO) carrying benzylic ether bridging groups is reported. By hydrolysis and condensation of the new designed chiral organosilica precursor 1,4-bis(triethoxysilyl)-2-(1-methoxyethyl)benzene (BTEMEB) in the presence of the non-ionic oligomeric surfactant Brij 76 as supramolecular structure-directing agent under acidic conditions, an ordered mesoporous chiral benzylic ether-bridged hybrid material with a high specific surface area was obtained. The chiral PMO precursor was synthesized in a four-step reaction from 1,4-dibromobenzene as the starting compound. The evidence for the presence of the chiral units in the organosilica precursor as well as inside the PMO material is provided by optical activity measurements.

Periodic Mesoporous Organosilicas with Helical and Concentric Circular Pore Architectures

“…[4][5][6][7][8][9] The presence of organic functional groups in mesoporous frameworks can modify the hydrophilicity/hydrophobicity of pore surface as well as the surface reactivity of PMOs, which provide the opportunity to tune mechanical, electronic, and optical properties of hybrid materials with a wide range of applications. [10][11][12][13][14][15] As a consequence, the assembly of PMOs with controlled pore architectures and morphologies has always been a global focus in this field.…”

Periodic Mesoporous Organosilicas: from simple to complex bridges; a comprehensive overview of functions, morphologies and applications

“…The enantiomeric purity of the organosilicas was determined to be >95% ee in materials obtained under acidic conditions. Fro¨ba et al 183 reported the synthesis of a chiral precursor carrying benzylic ether bridging groups (54). They were able to produce pure PMOs with highly ordered mesostructures and surface area of 820 m 2 g À1 .…”

Funktionsmaterialien: von harten zu weichen porösen Netzwerken

“…Dies gelang durch die asymmetrische Hydroborierung an einer Ethylen-verbrückten Organosilicatvorstufe, die nach Kondensation die weitere Umsetzung zu chiralen Hydroxy-(1) [84] oder Aminogruppen (2) [85] ermöglichte. Weitere chirale PMOs wurden durch asymmetrische Hydrierung einer Ketogruppe an einer Phenyl-verbrückten Vorstufe (3), [86] durch asymmetrische Hydrosilylierung einer Phenylsilyletheneinheit (4) [87] oder durch Racematspaltung einer axial-chiralen, biphenylverbrückten Vorstufe erhalten (5). [88] Poröse Organosilicate mit stabiler Porenstruktur konnten unter alleiniger Verwendung dieser Vorstufen hergestellt werden.…”