Revisiting carboxylic groups functionalization of silica sol-gel materials

RIVAS, MA VERÓNICA; ARENAS MUÑETON, MA. JOSÉ; BORDONI, ANDREA V.; SPAGNUOLO, CARLA C.; LOMBARDO, MA VERÓNICA; WOLOSIUK, ALEJANDRO

JOURNAL OF MATERIALS CHEMISTRY

ROYAL SOC CHEMISTRY

Lugar: CAMBRIDGE; Año: 2023 vol. 11 p. 1628 - 1653

0959-9428

The carboxylic chemical group is a ubiquitous moiety present in amino acids, a ligand for transition metals, a colloidal stabilizer, 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 to 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 start analyzing the importance of the COOH groups in the area of materials science, the commercial availability of carboxylic-based silanes and present new approaches for obtaining COOH-based organoalkoxide precursors. Undoubtedly, this will attract a widespread interest for the ultimate design of highly integrated chemical platforms.