Revisiting carboxylic group functionalization of silica sol-gel materials

The carboxylic chemical group is a ubiquitous moiety present in amino acids, a ligand for transition metals, a colloidal stabilizer, and a weak acidic ion-exchanger in polymeric resins and given this property, it is attractive for responsive materials or nanopore-based gating applications. As the number of uses increases, subtle requirements are imposed on this molecular group when anchored to various platforms for the functioning of an integrated chemical system. In this context, silica stands as an inert and multipurpose platform that enables the anchoring of multiple chemical entities combined through several orthogonal synthesis methods on the interface. Surface chemical modification relies on the use of organoalkoxysilanes that must meet the demand of tuned chemical properties; this, in turn, urges for innovative approaches for having an improved, but simple, organic toolbox. Starting from commonly available molecular precursors, several approaches have emerged: hydrosilylation, click thiol-ene additions, the use of carbodiimides or the reaction between cyclic anhydrides and anchored amines. In this review, we analyze the importance of the COOH groups in the area of materials science and the commercial availability of COOH-based silanes and present new approaches for obtaining COOH-based organoalkoxide precursors. Undoubtedly, this will attract widespread interest for the ultimate design of highly integrated chemical platforms.

Cooperative assembly of redistributed arylgermanium-bearing alkoxysilanes in a mesostructured siloxane network

Three redistributed arylgermanium-bearing mono-, bis- and tris-triethoxysilyl arms were designed, cocondensed with TEOS to access SBA-15-type materials and embedded in chitosan to prepare functional bioplastics.

Periodic mesoporous organosilicas derived from amphiphilic bulky polymethylsiloxane

Depending on the synthetic conditions (surfactant, acid, base, and presence or absence of TEOS), the sol–gel polymerization of functionalized polyorganosiloxane affords various textured silica-based materials.

Haemolytic activity and cellular toxicity of SBA-15-type silicas: elucidating the role of the mesostructure, surface functionality and linker length

Haemolytic activity and cellular toxicity of native, amino-, mercapto-, and carboxy-terminated SBA-15-type silicates were investigated.