Preparation of a photochromic glass doped with methylviologen radical cation via a sol-gel process

Abstract

Methylviologen cation radical is produced by photolysis of methyl viologen dichloride entrapped in a sol-gel glass. The sol-gel glass is shown to be microporous, and it is suggested that the microporosity prevents oxygen diffusion thereby helping to extend the lifetime of the cation radical to a period of months. Initial losses of a substantial fraction of the charge separation are not observed. These results bear directly on efficient photochemical energy storage.

A versatile route to organically-modified silicas and porous silicas via the non-hydrolytic sol–gel process

“…Solid-state 13 C and 29 Si NMR results support the formation of the expected structures. 13 C CP-MAS NMR spectra show the relevant carbon resonances.…”

“…Solid-state 29 Si and 13 C cross polarised (CP) and directly polarised (DP) nuclear magnetic resonance (NMR) spectroscopy was undertaken at the University of Durham, at ambient temperature on a Varian UNITYplus spectrometer. Spectra were recorded against an external TMS standard with magic angle spinning (MAS) at a spinning rate of 4300 Hz and an angle of 54.7³.…”

“…electronic 8 ) materials, catalysis and catalyst supports, 9 ceramics, 9,10 sensor applications 1,11,12 and active glasses. 1,13,14 The most common approach has involved the preparation of sol±gel hybrids, including the combination of inorganic oxides (particularly silica) with polymers 6,7,15 and the formation of organically-modi®ed silica (ormosils) from alkylalkoxysilanes. 16±18 All of these methods use the well-established hydrolytic route to the oxide, involving the hydrolysis and condensation reactions of alkoxide (or other) precursors, usually in a solvent system carefully chosen to avoid the common problem of premature phase separation.…”

Photo-sensitive hybrids constructed from diphenyliodonium and metal-thiocyanates: photo-induced structure and property transformations

“…1 For example, better thermal/photochemical stability and higher photo-induced charge separation efficiency can be achieved in these hybrid solids. 2,3 Recently, as a photoactive component with strong electron-accepting behaviors, excellent redox characteristics and sensitive photo/thermal chromisms, viologens have been widely used in the construction of functional charge-transfer (CT) complexes, whose electron transfer processes were accompanied by simultaneous generation of free radicals. [4][5][6][7] However, some disadvantages have emerged in viologen-based composite materials, including slow photo-responsibility and reversibility.…”

Transmission Electron Microscopy Characterization and Application of Sol-Gel Membranes

“…In recent years, the sol-gel technique has been successfully applied to prepare functional ceramic and glass materials for various applications in protective or decorative films, coatings, separation membranes, sensing matrices, and optical and electrical devices. Sol-gel-derived thin films with specific functions have been gaining the most attention among the sol-gel materials (Brinker and Schever, 1990;Klein, 1988;Hench and West, 1990;Avnir, 1995;Lev et al, 1997;Dunwila et al, 1996;Dai et al, 1995;Dunbar et al, 1996;Sanchez and Ribot, 1994;Lu et al, 1997;Fehlner, 1997;Munro et al, 1997;Sakka, 1990). The ability to control the microstructural features of deposited films by ad-justing many variables, such as the nature of the precursor, composition, solvent, pH, temperature, and additives, is an advantage of sol-gel processing over conventional thin-film processing techniques (Brinker et al, 1992;Mehrotra, 1990;Sanchez and In, 1992;Corriu and Leclercq, 1996;Brinker and Schever, 1985).…”