Isomeric olefinic periodic mesoporous organosilicas: an emerging class of versatile nanomaterials

Porous materials appear widely in nature and are the subject of intense study in many research areas owing to their unique properties. Their ability to interact with atoms, ions and molecules has lead to their wide spread applicability in sorption, catalysis, chromatography, ion exchange, micro-electronics, environmental technology, controlled drug release, . . . In the field of porous materials, scientists aim to control the size, shape, uniformity and periodicity of porous space and the atoms and molecules that define it. By controlling and fine-tuning these properties, materials can be engineered to meet the desired function and behaviour in a particular application. The presented research work describes the development, characterization and catalytic application of diastereoisomeric olefinic periodic mesoporous organosilicas (PMOs). PMOs are very unique in their compositional structure. The organic groups are covalently bonded within the siliceous network and hence are an intrinsic constituent of the mesoporous framework. The high loading and uniform distribution of organic groups in the pore walls of these open porous structures is a distinctive feature which allows for the easy tailoring of the PMO properties. From this perspective olefinic PMOs are very appealing, as they offer plenty of opportunities for surface modification based on olefin chemistry. To date, only limited research has been done on these very promising type of organic-inorganic hybrid materials and their potential in various applications has not been explored yet. The main goal of this research work has been the development of a novel class of versatile olefinic PMOs, which consist of diastereoisomerically configured organic bridges in their pore walls. The aim was to investigate new synthesis strategies which enable the synthesis of highly stable hybrid materials with controllable chemical and physical properties. By means of a detailed analysis of the developed PMO materials, an effort has also been made to understand the complex mechanisms involved in the supramolecular self-assembly process of ethenylene-bridged PMOs. Furthermore, with the intent of expanding the scope of olefinic PMOs, both the synthesis of new materials and the application thereof in catalysis has been studied

Isomeric periodic mesoporous organosilicas with controllable properties

The synthesis procedure for isomeric periodic mesoporous organosilicas with E-configured ethenylene bridges was investigated using the homemade pure E-isomer of 1,2-bis(triethoxysilyl)ethene. The pH, aging temperature and the presence of cosolvents played a key role in obtaining well-ordered mesoporous materials with controllable properties and morphologies. By fine-tuning the reaction mixture acidity, PMOs with high surface areas and pore volumes could be attained. By selecting various alcohols as cosolvents and optimizing the alcohol concentration, PMOs with crystal-like disc shaped, fibrous and spherical particle morphologies were obtained. The synthesis temperature of these ethenylene-bridged PMOs influences the pore size, structure, connectivity and volume

Ordered mesoporous materials at the beginning of the third millennium : new strategies to create hybrid and non-siliceous variants

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Ultra fast synthesis of plugged ethenylene-bridged PMOs

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