Organically Modified Transition-Metal Oxide Mesoporous Thin Films and Xerogels

Abstract

Organic molecules have been incorporated into the pore system of mesoporous TiO2 and ZrO2 xerogels and thin films. Surface-modifying functions include alkyl, aryl, amino, sulfonate, thiol, and polyol. Phosphate, phosphonate, carboxylate, and polyphenol were used as grafting groups. The incorporation of these functions into the mesoporous network (typically 2−8 μmol/m2) was monitored by crossing FTIR and EDS. In particular, the cases of dihexadecyl phosphate, monododecyl phosphate, 3-nitrophthalic acid, TIRON (disodium 1,2-dihydroxybenzene, 3,5-disulfonate), and thiol-bearing carboxylates are discussed. Uptake experiments suggest that the pore structure plays a key role in the accessibility of the pore system. Leaching experiments in different solvents and conditions were performed to assess the anchoring of the grafted functions. This permits tailoring of the molecule grafting, from firmly anchored functions to groups with controlled lability.