Generation and Reactions of Organic Radical Cations in Zeolites

Optical properties of chalcogen-loaded zeolite (ZSM-5)

“…Here, the zeolite, a porous crystal with typical compositions of Al-Si-O having varied (more than 100 kinds [2]) structures, has been demonstrated to work as a good matrix for producing well-defined nano-structures [3]. And, a lot of researches have been reported for a variety of combinations of a zeolite and a guest element, which may be organic [3][4][5], inorganic [6], or metallic [3]. Among those, pioneering work by Bogomorov et al has demonstrated that a chalcogen behaves as an interesting guest [7][8][9], partly because the chalcogen forms molecules with ring and chain structures, which may not produce many dangling bonds when nano-structured.…”

Photoresponsive Porous Organosilicas

“…The first PMO solid contains viologen units forming part of the silicate wall. Viologens have been widely used to form charge-transfer complexes with electron-rich molecules and also as electron acceptors in photoinduced electron transfer [2]. The corresponding radical cation, generated upon electron transfer, can be characterized unambiguously by Raman and optical spectroscopy.…”

“…The synthesis of mesoporous materials [1] by Mobil researchers in 1991 constituted a significant breakthrough in the field of host-guest chemistry [2] and catalysis [3]. Ordered mesoporous silicas overcame the limitation of microporous zeolites in terms of the molecular size of the organic molecules that can be incorporated within the porous silicate structure.…”

“…Ordered mesoporous silicas overcame the limitation of microporous zeolites in terms of the molecular size of the organic molecules that can be incorporated within the porous silicate structure. MCM silicates exhibit a mononodal pore size distribution that can be controlled during the synthesis from 2 to 10 nm, thus resulting in a logical extension of the zeolite supramolecular chemistry, limited to the micropore domain (pore size 0.5-1.4 nm) [2]. The most common and easy-to-prepare structured mesoporous material is MCM-41; its internal voids are formed by an array of parallel hexagonal channels typically of 3-4 nm diameter.…”

“…The remarkable pore size and internal volume places MCM-41 materials in the top echelon of porous materials, being particularly well suited to adsorb large organic guests in their interior. Many systems have been reported in which the molecular properties of the guest are varied upon adsorption into MCM-41 particles [2]. However, owing to the unidirectional topology of the MCM-41 voids and their uniform pore size, adsorbates could, in principle, also be desorbed and extracted out of the mesopores.…”