Periodic mesoporous organosilicas with organic groups inside the channel walls

Abstract

also be transferred from the highest occupied molecular orbital (HOMO) of the dye to the Fermi level of the dopant formate, so blocking electron±hole recombination 3 . Our results from emulsions sensitized by a carbocyanine thought to ful®ll the above criterion indicate that the sensitivity is indeed increased (Fig. 4), compared to emulsions without formate supposed to absorb the same quantity of photons. Depending on the surface coverage by dye molecules, these are in the form of either monomers or Jaggregates, which are two-dimensional arrays of edged-on adsorbed dye molecules with a large slip angle. The difference is about DlogI 3 t exp 0:9 for emulsions sensitized by dye monomers (l max 480 and 500 nm), excited at l exp > 477 nm; for emulsions sensitized by J-aggregates (additional l max at 552 nm), excited at l exp > 519 nm, we obtain DlogI 3 t exp 0:7. This enables us to assess the effect of aggregates only without coexisting monomers. The sensitivity enhancement that is systematically observed in the presence of formate ion therefore attests to ef®cient hole transfer to the dopant formate from the HOMO level of the dye, in both the monomer and the J-aggregate forms. This mechanism is comparable with the scavenging of the intrinsic hole created by direct AgBr excitation, and results in a marked inhibition of recombination. M

Periodic mesoporous organosilicas for advanced applications

“…1, 2,6 General synthesis methods for PMOs have been well reviewed in previous review articles. 6,8 Bis-silane holds an organic functional linker between silicon atoms and has a structure of (R 0 O) 3 Si-R-Si(OR 0 ) 3 , with OR 0 denoting the hydrolyzable group (usually ethoxy or methoxy groups) and R the functional linker.…”

“…The hybridization of inorganic and organic species on molecular to mesoscopic scales is a powerful tool for developing functional materials because their cooperative and synergetic effects, as well as the compatibility of different functionalities, can be introduced in the design of such materials. 1 In this context, three groups (Ozin and co-workers, 2 Inagaki and co-workers 3 and Stein and co-workers 4 ) independently developed a novel class of organic-inorganic nanocomposites known as periodic mesoporous organosilicas (PMOs) [2][3][4][5] in 1999. In PMOs, the organic groups are located within the channel walls as bridges between the Si centers ((R 0 O) 3 Si-R-Si(OR 0 ) 3 (R 0 ¼ methyl or ethyl, R ¼ the bridged organic groups)).…”

Adsorption of hydrogen peroxide on functionalized mesoporous silica surfaces

“…Periodic mesoporous organosilicas (PMOs) are materials with modified matrices but preserved organized pore system and narrow pore size distribution. They were first synthesized in 1999 by three groups working independently [39][40][41]. Until now, various PMOs are known: ethane- [39], ethene- [40], benzene- [42], bisphenyl-bridged [43], etc.…”

Ethenylene-bridged periodic mesoporous organosilicas with ultra-large mesopores

“…1 They are prepared via the direct condensation of bridged organosilanes, most commonly of the type (RO) 3 Si-R 0 -Si(OR) 3 , in the presence of a structure directing agent. This way nanocomposites with a high organic content can be obtained while preserving the pore ordering and uniformity.…”