Organically Modified Transition-Metal Oxide Mesoporous Thin Films and Xerogels

Abstract

Organic molecules have been incorporated into the pore system of mesoporous TiO 2 and ZrO 2 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/m 2 ) 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.

The biocompatability of mesoporous inorganic–organic hybrid resin films with ionic and hydrophilic characteristics

“…Based on the documented chemistry, it is plausible that the formation of a chelate complex between the enolic form of catecholic salt and Ti ion at low pH is thoroughly promoted in order to functionalize the entire surface of the mesoporous SiO 2 -TiO 2 network with sulfonate groups, whereas the quinone form at high pH is unsuitable for the formation of a hydrophilic Ti-catecholic salt chelate complex [41]. Furthermore, the INR material solutions turned a red-orange color, according to the intense absorption at 450 nm, providing a spectroscopic evidence for the formation of the Ti-catecholic salt complex [48], while the plain SiO 2 -TiO 2 resin with no sulfonation remained clear with no tint. Coincidently, energy dispersive X-Ray spectroscopy (EDS) analyses of the HR-4 resin found a S/Ti mol ratio of 0.49, indicating a catecholic salt/Ti mol ratio of 0.245, that is equivalent to the initial mixing ratio.…”

Photonic Crystals from Ordered Mesoporous Thin‐Film Functional Building Blocks

“…This sequence of procedures leads reproducibly to transparent crack-free thin films with well-defined spatially separated 3D interconnected and organized mesopore arrays. Titania layers were selectively post-functionalized by grafting bifunctional molecules, as previously reported [22]. The bifunctional molecules adsorb onto the titania and silica surface; however, molecules can be completely removed from the silica surface after thorough washing with THF [6].…”

“…The mesopores located on the top of the film are the access windows to the entire mesopore network present in the stack. [22] A study of the accessibility through these pores was carried out by monitoring the infrared transmission spectra as a function of time for TF-SF structures with different N values, in contact with a solution of DHDP in tetrahydrofuran (THF). Figure 9b shows that DHDP uptake increases with the number of layers N present in TF-SF multilayers, indicating that even a bulky molecule is able to diffuse and totally reach at least up to four layers inside the stack.…”

Metal Phosphonate Hybrid Mesostructures: Environmentally Friendly Multifunctional Materials for Clean Energy and Other Applications

“…Indeed, mesostructured phosphonate-based hybrids were reported to have different morphologies, such as macrochannels and microspheres. [13,16] Many monophosphonic-acid-modified metal oxides have been reported, [17,18] confirming the feasibility of grafting phosphonic acids onto the surface or pore walls of various oxides. By using organically bridged polyphosphonic acids as coupling molecules, the homogeneous and efficient incorporation of organic functional groups into the structure of the materials can be realized.…”